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What is a Literature Review? How to Write It (with Examples)

A literature review is a critical analysis and synthesis of existing research on a particular topic. It provides an overview of the current state of knowledge, identifies gaps, and highlights key findings in the literature. 1 The purpose of a literature review is to situate your own research within the context of existing scholarship, demonstrating your understanding of the topic and showing how your work contributes to the ongoing conversation in the field. Learning how to write a literature review is a critical tool for successful research. Your ability to summarize and synthesize prior research pertaining to a certain topic demonstrates your grasp on the topic of study, and assists in the learning process. 

Table of Contents

• What is the purpose of literature review? 
• a. Habitat Loss and Species Extinction: 
• b. Range Shifts and Phenological Changes: 
• c. Ocean Acidification and Coral Reefs: 
• d. Adaptive Strategies and Conservation Efforts: 
• How to write a good literature review 
• Choose a Topic and Define the Research Question: 
• Decide on the Scope of Your Review: 
• Select Databases for Searches: 
• Conduct Searches and Keep Track: 
• Review the Literature: 
• Organize and Write Your Literature Review: 
• Frequently asked questions 

What is a literature review?

A well-conducted literature review demonstrates the researcher’s familiarity with the existing literature, establishes the context for their own research, and contributes to scholarly conversations on the topic. One of the purposes of a literature review is also to help researchers avoid duplicating previous work and ensure that their research is informed by and builds upon the existing body of knowledge.

What is the purpose of literature review?

A literature review serves several important purposes within academic and research contexts. Here are some key objectives and functions of a literature review: 2  

• Contextualizing the Research Problem: The literature review provides a background and context for the research problem under investigation. It helps to situate the study within the existing body of knowledge. 
• Identifying Gaps in Knowledge: By identifying gaps, contradictions, or areas requiring further research, the researcher can shape the research question and justify the significance of the study. This is crucial for ensuring that the new research contributes something novel to the field. 
• Understanding Theoretical and Conceptual Frameworks: Literature reviews help researchers gain an understanding of the theoretical and conceptual frameworks used in previous studies. This aids in the development of a theoretical framework for the current research. 
• Providing Methodological Insights: Another purpose of literature reviews is that it allows researchers to learn about the methodologies employed in previous studies. This can help in choosing appropriate research methods for the current study and avoiding pitfalls that others may have encountered. 
• Establishing Credibility: A well-conducted literature review demonstrates the researcher’s familiarity with existing scholarship, establishing their credibility and expertise in the field. It also helps in building a solid foundation for the new research. 
• Informing Hypotheses or Research Questions: The literature review guides the formulation of hypotheses or research questions by highlighting relevant findings and areas of uncertainty in existing literature. 

Literature review example

Let’s delve deeper with a literature review example: Let’s say your literature review is about the impact of climate change on biodiversity. You might format your literature review into sections such as the effects of climate change on habitat loss and species extinction, phenological changes, and marine biodiversity. Each section would then summarize and analyze relevant studies in those areas, highlighting key findings and identifying gaps in the research. The review would conclude by emphasizing the need for further research on specific aspects of the relationship between climate change and biodiversity. The following literature review template provides a glimpse into the recommended literature review structure and content, demonstrating how research findings are organized around specific themes within a broader topic. 

Literature Review on Climate Change Impacts on Biodiversity:

Climate change is a global phenomenon with far-reaching consequences, including significant impacts on biodiversity. This literature review synthesizes key findings from various studies: 

a. Habitat Loss and Species Extinction:

Climate change-induced alterations in temperature and precipitation patterns contribute to habitat loss, affecting numerous species (Thomas et al., 2004). The review discusses how these changes increase the risk of extinction, particularly for species with specific habitat requirements. 

b. Range Shifts and Phenological Changes:

Observations of range shifts and changes in the timing of biological events (phenology) are documented in response to changing climatic conditions (Parmesan & Yohe, 2003). These shifts affect ecosystems and may lead to mismatches between species and their resources. 

c. Ocean Acidification and Coral Reefs:

The review explores the impact of climate change on marine biodiversity, emphasizing ocean acidification’s threat to coral reefs (Hoegh-Guldberg et al., 2007). Changes in pH levels negatively affect coral calcification, disrupting the delicate balance of marine ecosystems. 

d. Adaptive Strategies and Conservation Efforts:

Recognizing the urgency of the situation, the literature review discusses various adaptive strategies adopted by species and conservation efforts aimed at mitigating the impacts of climate change on biodiversity (Hannah et al., 2007). It emphasizes the importance of interdisciplinary approaches for effective conservation planning. 

How to write a good literature review

Writing a literature review involves summarizing and synthesizing existing research on a particular topic. A good literature review format should include the following elements. 

Introduction: The introduction sets the stage for your literature review, providing context and introducing the main focus of your review. 

• Opening Statement: Begin with a general statement about the broader topic and its significance in the field. 
• Scope and Purpose: Clearly define the scope of your literature review. Explain the specific research question or objective you aim to address. 
• Organizational Framework: Briefly outline the structure of your literature review, indicating how you will categorize and discuss the existing research. 
• Significance of the Study: Highlight why your literature review is important and how it contributes to the understanding of the chosen topic. 
• Thesis Statement: Conclude the introduction with a concise thesis statement that outlines the main argument or perspective you will develop in the body of the literature review. 

Body: The body of the literature review is where you provide a comprehensive analysis of existing literature, grouping studies based on themes, methodologies, or other relevant criteria. 

• Organize by Theme or Concept: Group studies that share common themes, concepts, or methodologies. Discuss each theme or concept in detail, summarizing key findings and identifying gaps or areas of disagreement. 
• Critical Analysis: Evaluate the strengths and weaknesses of each study. Discuss the methodologies used, the quality of evidence, and the overall contribution of each work to the understanding of the topic. 
• Synthesis of Findings: Synthesize the information from different studies to highlight trends, patterns, or areas of consensus in the literature. 
• Identification of Gaps: Discuss any gaps or limitations in the existing research and explain how your review contributes to filling these gaps. 
• Transition between Sections: Provide smooth transitions between different themes or concepts to maintain the flow of your literature review. 

Conclusion: The conclusion of your literature review should summarize the main findings, highlight the contributions of the review, and suggest avenues for future research. 

• Summary of Key Findings: Recap the main findings from the literature and restate how they contribute to your research question or objective. 
• Contributions to the Field: Discuss the overall contribution of your literature review to the existing knowledge in the field. 
• Implications and Applications: Explore the practical implications of the findings and suggest how they might impact future research or practice. 
• Recommendations for Future Research: Identify areas that require further investigation and propose potential directions for future research in the field. 
• Final Thoughts: Conclude with a final reflection on the importance of your literature review and its relevance to the broader academic community. 

Conducting a literature review

Conducting a literature review is an essential step in research that involves reviewing and analyzing existing literature on a specific topic. It’s important to know how to do a literature review effectively, so here are the steps to follow: 1  

Choose a Topic and Define the Research Question:

• Select a topic that is relevant to your field of study. 
• Clearly define your research question or objective. Determine what specific aspect of the topic do you want to explore? 

Decide on the Scope of Your Review:

• Determine the timeframe for your literature review. Are you focusing on recent developments, or do you want a historical overview? 
• Consider the geographical scope. Is your review global, or are you focusing on a specific region? 
• Define the inclusion and exclusion criteria. What types of sources will you include? Are there specific types of studies or publications you will exclude? 

Select Databases for Searches:

• Identify relevant databases for your field. Examples include PubMed, IEEE Xplore, Scopus, Web of Science, and Google Scholar. 
• Consider searching in library catalogs, institutional repositories, and specialized databases related to your topic. 

Conduct Searches and Keep Track:

• Develop a systematic search strategy using keywords, Boolean operators (AND, OR, NOT), and other search techniques. 
• Record and document your search strategy for transparency and replicability. 
• Keep track of the articles, including publication details, abstracts, and links. Use citation management tools like EndNote, Zotero, or Mendeley to organize your references. 

Review the Literature:

• Evaluate the relevance and quality of each source. Consider the methodology, sample size, and results of studies. 
• Organize the literature by themes or key concepts. Identify patterns, trends, and gaps in the existing research. 
• Summarize key findings and arguments from each source. Compare and contrast different perspectives. 
• Identify areas where there is a consensus in the literature and where there are conflicting opinions. 
• Provide critical analysis and synthesis of the literature. What are the strengths and weaknesses of existing research? 

Organize and Write Your Literature Review:

• Literature review outline should be based on themes, chronological order, or methodological approaches. 
• Write a clear and coherent narrative that synthesizes the information gathered. 
• Use proper citations for each source and ensure consistency in your citation style (APA, MLA, Chicago, etc.). 
• Conclude your literature review by summarizing key findings, identifying gaps, and suggesting areas for future research. 

The literature review sample and detailed advice on writing and conducting a review will help you produce a well-structured report. But remember that a literature review is an ongoing process, and it may be necessary to revisit and update it as your research progresses. 

Frequently asked questions

A literature review is a critical and comprehensive analysis of existing literature (published and unpublished works) on a specific topic or research question and provides a synthesis of the current state of knowledge in a particular field. A well-conducted literature review is crucial for researchers to build upon existing knowledge, avoid duplication of efforts, and contribute to the advancement of their field. It also helps researchers situate their work within a broader context and facilitates the development of a sound theoretical and conceptual framework for their studies.

Literature review is a crucial component of research writing, providing a solid background for a research paper’s investigation. The aim is to keep professionals up to date by providing an understanding of ongoing developments within a specific field, including research methods, and experimental techniques used in that field, and present that knowledge in the form of a written report. Also, the depth and breadth of the literature review emphasizes the credibility of the scholar in his or her field.  

Before writing a literature review, it’s essential to undertake several preparatory steps to ensure that your review is well-researched, organized, and focused. This includes choosing a topic of general interest to you and doing exploratory research on that topic, writing an annotated bibliography, and noting major points, especially those that relate to the position you have taken on the topic. 

Literature reviews and academic research papers are essential components of scholarly work but serve different purposes within the academic realm. 3 A literature review aims to provide a foundation for understanding the current state of research on a particular topic, identify gaps or controversies, and lay the groundwork for future research. Therefore, it draws heavily from existing academic sources, including books, journal articles, and other scholarly publications. In contrast, an academic research paper aims to present new knowledge, contribute to the academic discourse, and advance the understanding of a specific research question. Therefore, it involves a mix of existing literature (in the introduction and literature review sections) and original data or findings obtained through research methods. 

Literature reviews are essential components of academic and research papers, and various strategies can be employed to conduct them effectively. If you want to know how to write a literature review for a research paper, here are four common approaches that are often used by researchers.  Chronological Review: This strategy involves organizing the literature based on the chronological order of publication. It helps to trace the development of a topic over time, showing how ideas, theories, and research have evolved.  Thematic Review: Thematic reviews focus on identifying and analyzing themes or topics that cut across different studies. Instead of organizing the literature chronologically, it is grouped by key themes or concepts, allowing for a comprehensive exploration of various aspects of the topic.  Methodological Review: This strategy involves organizing the literature based on the research methods employed in different studies. It helps to highlight the strengths and weaknesses of various methodologies and allows the reader to evaluate the reliability and validity of the research findings.  Theoretical Review: A theoretical review examines the literature based on the theoretical frameworks used in different studies. This approach helps to identify the key theories that have been applied to the topic and assess their contributions to the understanding of the subject.  It’s important to note that these strategies are not mutually exclusive, and a literature review may combine elements of more than one approach. The choice of strategy depends on the research question, the nature of the literature available, and the goals of the review. Additionally, other strategies, such as integrative reviews or systematic reviews, may be employed depending on the specific requirements of the research.

The literature review format can vary depending on the specific publication guidelines. However, there are some common elements and structures that are often followed. Here is a general guideline for the format of a literature review:  Introduction:   Provide an overview of the topic.  Define the scope and purpose of the literature review.  State the research question or objective.  Body:   Organize the literature by themes, concepts, or chronology.  Critically analyze and evaluate each source.  Discuss the strengths and weaknesses of the studies.  Highlight any methodological limitations or biases.  Identify patterns, connections, or contradictions in the existing research.  Conclusion:   Summarize the key points discussed in the literature review.  Highlight the research gap.  Address the research question or objective stated in the introduction.  Highlight the contributions of the review and suggest directions for future research.

Both annotated bibliographies and literature reviews involve the examination of scholarly sources. While annotated bibliographies focus on individual sources with brief annotations, literature reviews provide a more in-depth, integrated, and comprehensive analysis of existing literature on a specific topic. The key differences are as follows: 

References 

• Denney, A. S., & Tewksbury, R. (2013). How to write a literature review.  Journal of criminal justice education ,  24 (2), 218-234. 
• Pan, M. L. (2016).  Preparing literature reviews: Qualitative and quantitative approaches . Taylor & Francis. 
• Cantero, C. (2019). How to write a literature review.  San José State University Writing Center . 

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Writing a Literature Review

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A literature review is a document or section of a document that collects key sources on a topic and discusses those sources in conversation with each other (also called synthesis ). The lit review is an important genre in many disciplines, not just literature (i.e., the study of works of literature such as novels and plays). When we say “literature review” or refer to “the literature,” we are talking about the research ( scholarship ) in a given field. You will often see the terms “the research,” “the scholarship,” and “the literature” used mostly interchangeably.

Where, when, and why would I write a lit review?

There are a number of different situations where you might write a literature review, each with slightly different expectations; different disciplines, too, have field-specific expectations for what a literature review is and does. For instance, in the humanities, authors might include more overt argumentation and interpretation of source material in their literature reviews, whereas in the sciences, authors are more likely to report study designs and results in their literature reviews; these differences reflect these disciplines’ purposes and conventions in scholarship. You should always look at examples from your own discipline and talk to professors or mentors in your field to be sure you understand your discipline’s conventions, for literature reviews as well as for any other genre.

A literature review can be a part of a research paper or scholarly article, usually falling after the introduction and before the research methods sections. In these cases, the lit review just needs to cover scholarship that is important to the issue you are writing about; sometimes it will also cover key sources that informed your research methodology.

Lit reviews can also be standalone pieces, either as assignments in a class or as publications. In a class, a lit review may be assigned to help students familiarize themselves with a topic and with scholarship in their field, get an idea of the other researchers working on the topic they’re interested in, find gaps in existing research in order to propose new projects, and/or develop a theoretical framework and methodology for later research. As a publication, a lit review usually is meant to help make other scholars’ lives easier by collecting and summarizing, synthesizing, and analyzing existing research on a topic. This can be especially helpful for students or scholars getting into a new research area, or for directing an entire community of scholars toward questions that have not yet been answered.

What are the parts of a lit review?

Most lit reviews use a basic introduction-body-conclusion structure; if your lit review is part of a larger paper, the introduction and conclusion pieces may be just a few sentences while you focus most of your attention on the body. If your lit review is a standalone piece, the introduction and conclusion take up more space and give you a place to discuss your goals, research methods, and conclusions separately from where you discuss the literature itself.

Introduction:

• An introductory paragraph that explains what your working topic and thesis is
• A forecast of key topics or texts that will appear in the review
• Potentially, a description of how you found sources and how you analyzed them for inclusion and discussion in the review (more often found in published, standalone literature reviews than in lit review sections in an article or research paper)
• Summarize and synthesize: Give an overview of the main points of each source and combine them into a coherent whole
• Analyze and interpret: Don’t just paraphrase other researchers – add your own interpretations where possible, discussing the significance of findings in relation to the literature as a whole
• Critically Evaluate: Mention the strengths and weaknesses of your sources
• Write in well-structured paragraphs: Use transition words and topic sentence to draw connections, comparisons, and contrasts.

Conclusion:

• Summarize the key findings you have taken from the literature and emphasize their significance
• Connect it back to your primary research question

How should I organize my lit review?

Lit reviews can take many different organizational patterns depending on what you are trying to accomplish with the review. Here are some examples:

• Chronological : The simplest approach is to trace the development of the topic over time, which helps familiarize the audience with the topic (for instance if you are introducing something that is not commonly known in your field). If you choose this strategy, be careful to avoid simply listing and summarizing sources in order. Try to analyze the patterns, turning points, and key debates that have shaped the direction of the field. Give your interpretation of how and why certain developments occurred (as mentioned previously, this may not be appropriate in your discipline — check with a teacher or mentor if you’re unsure).
• Thematic : If you have found some recurring central themes that you will continue working with throughout your piece, you can organize your literature review into subsections that address different aspects of the topic. For example, if you are reviewing literature about women and religion, key themes can include the role of women in churches and the religious attitude towards women.
• Qualitative versus quantitative research
• Empirical versus theoretical scholarship
• Divide the research by sociological, historical, or cultural sources
• Theoretical : In many humanities articles, the literature review is the foundation for the theoretical framework. You can use it to discuss various theories, models, and definitions of key concepts. You can argue for the relevance of a specific theoretical approach or combine various theorical concepts to create a framework for your research.

What are some strategies or tips I can use while writing my lit review?

Any lit review is only as good as the research it discusses; make sure your sources are well-chosen and your research is thorough. Don’t be afraid to do more research if you discover a new thread as you’re writing. More info on the research process is available in our "Conducting Research" resources .

As you’re doing your research, create an annotated bibliography ( see our page on the this type of document ). Much of the information used in an annotated bibliography can be used also in a literature review, so you’ll be not only partially drafting your lit review as you research, but also developing your sense of the larger conversation going on among scholars, professionals, and any other stakeholders in your topic.

Usually you will need to synthesize research rather than just summarizing it. This means drawing connections between sources to create a picture of the scholarly conversation on a topic over time. Many student writers struggle to synthesize because they feel they don’t have anything to add to the scholars they are citing; here are some strategies to help you:

• It often helps to remember that the point of these kinds of syntheses is to show your readers how you understand your research, to help them read the rest of your paper.
• Writing teachers often say synthesis is like hosting a dinner party: imagine all your sources are together in a room, discussing your topic. What are they saying to each other?
• Look at the in-text citations in each paragraph. Are you citing just one source for each paragraph? This usually indicates summary only. When you have multiple sources cited in a paragraph, you are more likely to be synthesizing them (not always, but often
• Read more about synthesis here.

The most interesting literature reviews are often written as arguments (again, as mentioned at the beginning of the page, this is discipline-specific and doesn’t work for all situations). Often, the literature review is where you can establish your research as filling a particular gap or as relevant in a particular way. You have some chance to do this in your introduction in an article, but the literature review section gives a more extended opportunity to establish the conversation in the way you would like your readers to see it. You can choose the intellectual lineage you would like to be part of and whose definitions matter most to your thinking (mostly humanities-specific, but this goes for sciences as well). In addressing these points, you argue for your place in the conversation, which tends to make the lit review more compelling than a simple reporting of other sources.

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• What is a Literature Review? | Guide, Template, & Examples

What is a Literature Review? | Guide, Template, & Examples

Published on 22 February 2022 by Shona McCombes . Revised on 7 June 2022.

What is a literature review? A literature review is a survey of scholarly sources on a specific topic. It provides an overview of current knowledge, allowing you to identify relevant theories, methods, and gaps in the existing research.

There are five key steps to writing a literature review:

• Search for relevant literature
• Evaluate sources
• Identify themes, debates and gaps
• Outline the structure
• Write your literature review

A good literature review doesn’t just summarise sources – it analyses, synthesises, and critically evaluates to give a clear picture of the state of knowledge on the subject.

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Table of contents

Why write a literature review, examples of literature reviews, step 1: search for relevant literature, step 2: evaluate and select sources, step 3: identify themes, debates and gaps, step 4: outline your literature review’s structure, step 5: write your literature review, frequently asked questions about literature reviews, introduction.

• Quick Run-through
• Step 1 & 2

When you write a dissertation or thesis, you will have to conduct a literature review to situate your research within existing knowledge. The literature review gives you a chance to:

• Demonstrate your familiarity with the topic and scholarly context
• Develop a theoretical framework and methodology for your research
• Position yourself in relation to other researchers and theorists
• Show how your dissertation addresses a gap or contributes to a debate

You might also have to write a literature review as a stand-alone assignment. In this case, the purpose is to evaluate the current state of research and demonstrate your knowledge of scholarly debates around a topic.

The content will look slightly different in each case, but the process of conducting a literature review follows the same steps. We’ve written a step-by-step guide that you can follow below.

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Writing literature reviews can be quite challenging! A good starting point could be to look at some examples, depending on what kind of literature review you’d like to write.

• Example literature review #1: “Why Do People Migrate? A Review of the Theoretical Literature” ( Theoretical literature review about the development of economic migration theory from the 1950s to today.)
• Example literature review #2: “Literature review as a research methodology: An overview and guidelines” ( Methodological literature review about interdisciplinary knowledge acquisition and production.)
• Example literature review #3: “The Use of Technology in English Language Learning: A Literature Review” ( Thematic literature review about the effects of technology on language acquisition.)
• Example literature review #4: “Learners’ Listening Comprehension Difficulties in English Language Learning: A Literature Review” ( Chronological literature review about how the concept of listening skills has changed over time.)

You can also check out our templates with literature review examples and sample outlines at the links below.

Download Word doc Download Google doc

Before you begin searching for literature, you need a clearly defined topic .

If you are writing the literature review section of a dissertation or research paper, you will search for literature related to your research objectives and questions .

If you are writing a literature review as a stand-alone assignment, you will have to choose a focus and develop a central question to direct your search. Unlike a dissertation research question, this question has to be answerable without collecting original data. You should be able to answer it based only on a review of existing publications.

Make a list of keywords

Start by creating a list of keywords related to your research topic. Include each of the key concepts or variables you’re interested in, and list any synonyms and related terms. You can add to this list if you discover new keywords in the process of your literature search.

• Social media, Facebook, Instagram, Twitter, Snapchat, TikTok
• Body image, self-perception, self-esteem, mental health
• Generation Z, teenagers, adolescents, youth

Search for relevant sources

Use your keywords to begin searching for sources. Some databases to search for journals and articles include:

• Your university’s library catalogue
• Google Scholar
• Project Muse (humanities and social sciences)
• Medline (life sciences and biomedicine)
• EconLit (economics)
• Inspec (physics, engineering and computer science)

You can use boolean operators to help narrow down your search:

Read the abstract to find out whether an article is relevant to your question. When you find a useful book or article, you can check the bibliography to find other relevant sources.

To identify the most important publications on your topic, take note of recurring citations. If the same authors, books or articles keep appearing in your reading, make sure to seek them out.

You probably won’t be able to read absolutely everything that has been written on the topic – you’ll have to evaluate which sources are most relevant to your questions.

For each publication, ask yourself:

• What question or problem is the author addressing?
• What are the key concepts and how are they defined?
• What are the key theories, models and methods? Does the research use established frameworks or take an innovative approach?
• What are the results and conclusions of the study?
• How does the publication relate to other literature in the field? Does it confirm, add to, or challenge established knowledge?
• How does the publication contribute to your understanding of the topic? What are its key insights and arguments?
• What are the strengths and weaknesses of the research?

Make sure the sources you use are credible, and make sure you read any landmark studies and major theories in your field of research.

You can find out how many times an article has been cited on Google Scholar – a high citation count means the article has been influential in the field, and should certainly be included in your literature review.

The scope of your review will depend on your topic and discipline: in the sciences you usually only review recent literature, but in the humanities you might take a long historical perspective (for example, to trace how a concept has changed in meaning over time).

Remember that you can use our template to summarise and evaluate sources you’re thinking about using!

Take notes and cite your sources

As you read, you should also begin the writing process. Take notes that you can later incorporate into the text of your literature review.

It’s important to keep track of your sources with references to avoid plagiarism . It can be helpful to make an annotated bibliography, where you compile full reference information and write a paragraph of summary and analysis for each source. This helps you remember what you read and saves time later in the process.

You can use our free APA Reference Generator for quick, correct, consistent citations.

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To begin organising your literature review’s argument and structure, you need to understand the connections and relationships between the sources you’ve read. Based on your reading and notes, you can look for:

• Trends and patterns (in theory, method or results): do certain approaches become more or less popular over time?
• Themes: what questions or concepts recur across the literature?
• Debates, conflicts and contradictions: where do sources disagree?
• Pivotal publications: are there any influential theories or studies that changed the direction of the field?
• Gaps: what is missing from the literature? Are there weaknesses that need to be addressed?

This step will help you work out the structure of your literature review and (if applicable) show how your own research will contribute to existing knowledge.

• Most research has focused on young women.
• There is an increasing interest in the visual aspects of social media.
• But there is still a lack of robust research on highly-visual platforms like Instagram and Snapchat – this is a gap that you could address in your own research.

There are various approaches to organising the body of a literature review. You should have a rough idea of your strategy before you start writing.

Depending on the length of your literature review, you can combine several of these strategies (for example, your overall structure might be thematic, but each theme is discussed chronologically).

Chronological

The simplest approach is to trace the development of the topic over time. However, if you choose this strategy, be careful to avoid simply listing and summarising sources in order.

Try to analyse patterns, turning points and key debates that have shaped the direction of the field. Give your interpretation of how and why certain developments occurred.

If you have found some recurring central themes, you can organise your literature review into subsections that address different aspects of the topic.

For example, if you are reviewing literature about inequalities in migrant health outcomes, key themes might include healthcare policy, language barriers, cultural attitudes, legal status, and economic access.

Methodological

If you draw your sources from different disciplines or fields that use a variety of research methods , you might want to compare the results and conclusions that emerge from different approaches. For example:

• Look at what results have emerged in qualitative versus quantitative research
• Discuss how the topic has been approached by empirical versus theoretical scholarship
• Divide the literature into sociological, historical, and cultural sources

Theoretical

A literature review is often the foundation for a theoretical framework . You can use it to discuss various theories, models, and definitions of key concepts.

You might argue for the relevance of a specific theoretical approach, or combine various theoretical concepts to create a framework for your research.

Like any other academic text, your literature review should have an introduction , a main body, and a conclusion . What you include in each depends on the objective of your literature review.

The introduction should clearly establish the focus and purpose of the literature review.

If you are writing the literature review as part of your dissertation or thesis, reiterate your central problem or research question and give a brief summary of the scholarly context. You can emphasise the timeliness of the topic (“many recent studies have focused on the problem of x”) or highlight a gap in the literature (“while there has been much research on x, few researchers have taken y into consideration”).

Depending on the length of your literature review, you might want to divide the body into subsections. You can use a subheading for each theme, time period, or methodological approach.

As you write, make sure to follow these tips:

• Summarise and synthesise: give an overview of the main points of each source and combine them into a coherent whole.
• Analyse and interpret: don’t just paraphrase other researchers – add your own interpretations, discussing the significance of findings in relation to the literature as a whole.
• Critically evaluate: mention the strengths and weaknesses of your sources.
• Write in well-structured paragraphs: use transitions and topic sentences to draw connections, comparisons and contrasts.

In the conclusion, you should summarise the key findings you have taken from the literature and emphasise their significance.

If the literature review is part of your dissertation or thesis, reiterate how your research addresses gaps and contributes new knowledge, or discuss how you have drawn on existing theories and methods to build a framework for your research. This can lead directly into your methodology section.

A literature review is a survey of scholarly sources (such as books, journal articles, and theses) related to a specific topic or research question .

It is often written as part of a dissertation , thesis, research paper , or proposal .

There are several reasons to conduct a literature review at the beginning of a research project:

• To familiarise yourself with the current state of knowledge on your topic
• To ensure that you’re not just repeating what others have already done
• To identify gaps in knowledge and unresolved problems that your research can address
• To develop your theoretical framework and methodology
• To provide an overview of the key findings and debates on the topic

Writing the literature review shows your reader how your work relates to existing research and what new insights it will contribute.

The literature review usually comes near the beginning of your  dissertation . After the introduction , it grounds your research in a scholarly field and leads directly to your theoretical framework or methodology .

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What is a literature review?

A literature review is an integrated analysis -- not just a summary-- of scholarly writings and other relevant evidence related directly to your research question.  That is, it represents a synthesis of the evidence that provides background information on your topic and shows a association between the evidence and your research question.

A literature review may be a stand alone work or the introduction to a larger research paper, depending on the assignment.  Rely heavily on the guidelines your instructor has given you.

Why is it important?

A literature review is important because it:

• Explains the background of research on a topic.
• Demonstrates why a topic is significant to a subject area.
• Discovers relationships between research studies/ideas.
• Identifies major themes, concepts, and researchers on a topic.
• Identifies critical gaps and points of disagreement.
• Discusses further research questions that logically come out of the previous studies.

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1. Choose a topic. Define your research question.

Your literature review should be guided by your central research question.  The literature represents background and research developments related to a specific research question, interpreted and analyzed by you in a synthesized way.

• Make sure your research question is not too broad or too narrow.  Is it manageable?
• Begin writing down terms that are related to your question. These will be useful for searches later.
• If you have the opportunity, discuss your topic with your professor and your class mates.

2. Decide on the scope of your review

How many studies do you need to look at? How comprehensive should it be? How many years should it cover? 

• This may depend on your assignment.  How many sources does the assignment require?

3. Select the databases you will use to conduct your searches.

Make a list of the databases you will search. 

Where to find databases:

• use the tabs on this guide
• Find other databases in the Nursing Information Resources web page
• More on the Medical Library web page
• ... and more on the Yale University Library web page

4. Conduct your searches to find the evidence. Keep track of your searches.

• Use the key words in your question, as well as synonyms for those words, as terms in your search. Use the database tutorials for help.
• Save the searches in the databases. This saves time when you want to redo, or modify, the searches. It is also helpful to use as a guide is the searches are not finding any useful results.
• Review the abstracts of research studies carefully. This will save you time.
• Use the bibliographies and references of research studies you find to locate others.
• Check with your professor, or a subject expert in the field, if you are missing any key works in the field.
• Ask your librarian for help at any time.
• Use a citation manager, such as EndNote as the repository for your citations. See the EndNote tutorials for help.

Review the literature

Some questions to help you analyze the research:

• What was the research question of the study you are reviewing? What were the authors trying to discover?
• Was the research funded by a source that could influence the findings?
• What were the research methodologies? Analyze its literature review, the samples and variables used, the results, and the conclusions.
• Does the research seem to be complete? Could it have been conducted more soundly? What further questions does it raise?
• If there are conflicting studies, why do you think that is?
• How are the authors viewed in the field? Has this study been cited? If so, how has it been analyzed?

Tips: 

• Review the abstracts carefully.  
• Keep careful notes so that you may track your thought processes during the research process.
• Create a matrix of the studies for easy analysis, and synthesis, across all of the studies.
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How To Write A Literature Review - A Complete Guide

Table of Contents

A literature review is much more than just another section in your research paper. It forms the very foundation of your research. It is a formal piece of writing where you analyze the existing theoretical framework, principles, and assumptions and use that as a base to shape your approach to the research question.

Curating and drafting a solid literature review section not only lends more credibility to your research paper but also makes your research tighter and better focused. But, writing literature reviews is a difficult task. It requires extensive reading, plus you have to consider market trends and technological and political changes, which tend to change in the blink of an eye.

Now streamline your literature review process with the help of SciSpace Copilot. With this AI research assistant, you can efficiently synthesize and analyze a vast amount of information, identify key themes and trends, and uncover gaps in the existing research. Get real-time explanations, summaries, and answers to your questions for the paper you're reviewing, making navigating and understanding the complex literature landscape easier.

In this comprehensive guide, we will explore everything from the definition of a literature review, its appropriate length, various types of literature reviews, and how to write one.

What is a literature review?

A literature review is a collation of survey, research, critical evaluation, and assessment of the existing literature in a preferred domain.

Eminent researcher and academic Arlene Fink, in her book Conducting Research Literature Reviews , defines it as the following:

“A literature review surveys books, scholarly articles, and any other sources relevant to a particular issue, area of research, or theory, and by so doing, provides a description, summary, and critical evaluation of these works in relation to the research problem being investigated.

Literature reviews are designed to provide an overview of sources you have explored while researching a particular topic, and to demonstrate to your readers how your research fits within a larger field of study.”

Simply put, a literature review can be defined as a critical discussion of relevant pre-existing research around your research question and carving out a definitive place for your study in the existing body of knowledge. Literature reviews can be presented in multiple ways: a section of an article, the whole research paper itself, or a chapter of your thesis.

A literature review does function as a summary of sources, but it also allows you to analyze further, interpret, and examine the stated theories, methods, viewpoints, and, of course, the gaps in the existing content.

As an author, you can discuss and interpret the research question and its various aspects and debate your adopted methods to support the claim.

What is the purpose of a literature review?

A literature review is meant to help your readers understand the relevance of your research question and where it fits within the existing body of knowledge. As a researcher, you should use it to set the context, build your argument, and establish the need for your study.

What is the importance of a literature review?

The literature review is a critical part of research papers because it helps you:

• Gain an in-depth understanding of your research question and the surrounding area
• Convey that you have a thorough understanding of your research area and are up-to-date with the latest changes and advancements
• Establish how your research is connected or builds on the existing body of knowledge and how it could contribute to further research
• Elaborate on the validity and suitability of your theoretical framework and research methodology
• Identify and highlight gaps and shortcomings in the existing body of knowledge and how things need to change
• Convey to readers how your study is different or how it contributes to the research area

How long should a literature review be?

Ideally, the literature review should take up 15%-40% of the total length of your manuscript. So, if you have a 10,000-word research paper, the minimum word count could be 1500.

Your literature review format depends heavily on the kind of manuscript you are writing — an entire chapter in case of doctoral theses, a part of the introductory section in a research article, to a full-fledged review article that examines the previously published research on a topic.

Another determining factor is the type of research you are doing. The literature review section tends to be longer for secondary research projects than primary research projects.

What are the different types of literature reviews?

All literature reviews are not the same. There are a variety of possible approaches that you can take. It all depends on the type of research you are pursuing.

Here are the different types of literature reviews:

Argumentative review

It is called an argumentative review when you carefully present literature that only supports or counters a specific argument or premise to establish a viewpoint.

Integrative review

It is a type of literature review focused on building a comprehensive understanding of a topic by combining available theoretical frameworks and empirical evidence.

Methodological review

This approach delves into the ''how'' and the ''what" of the research question —  you cannot look at the outcome in isolation; you should also review the methodology used.

Systematic review

This form consists of an overview of existing evidence pertinent to a clearly formulated research question, which uses pre-specified and standardized methods to identify and critically appraise relevant research and collect, report, and analyze data from the studies included in the review.

Meta-analysis review

Meta-analysis uses statistical methods to summarize the results of independent studies. By combining information from all relevant studies, meta-analysis can provide more precise estimates of the effects than those derived from the individual studies included within a review.

Historical review

Historical literature reviews focus on examining research throughout a period, often starting with the first time an issue, concept, theory, or phenomenon emerged in the literature, then tracing its evolution within the scholarship of a discipline. The purpose is to place research in a historical context to show familiarity with state-of-the-art developments and identify future research's likely directions.

Theoretical Review

This form aims to examine the corpus of theory accumulated regarding an issue, concept, theory, and phenomenon. The theoretical literature review helps to establish what theories exist, the relationships between them, the degree the existing approaches have been investigated, and to develop new hypotheses to be tested.

Scoping Review

The Scoping Review is often used at the beginning of an article, dissertation, or research proposal. It is conducted before the research to highlight gaps in the existing body of knowledge and explains why the project should be greenlit.

State-of-the-Art Review

The State-of-the-Art review is conducted periodically, focusing on the most recent research. It describes what is currently known, understood, or agreed upon regarding the research topic and highlights where there are still disagreements.

Can you use the first person in a literature review?

When writing literature reviews, you should avoid the usage of first-person pronouns. It means that instead of "I argue that" or "we argue that," the appropriate expression would be "this research paper argues that."

Do you need an abstract for a literature review?

Ideally, yes. It is always good to have a condensed summary that is self-contained and independent of the rest of your review. As for how to draft one, you can follow the same fundamental idea when preparing an abstract for a literature review. It should also include:

• The research topic and your motivation behind selecting it
• A one-sentence thesis statement
• An explanation of the kinds of literature featured in the review
• Summary of what you've learned
• Conclusions you drew from the literature you reviewed
• Potential implications and future scope for research

Here's an example of the abstract of a literature review

Is a literature review written in the past tense?

Yes, the literature review should ideally be written in the past tense. You should not use the present or future tense when writing one. The exceptions are when you have statements describing events that happened earlier than the literature you are reviewing or events that are currently occurring; then, you can use the past perfect or present perfect tenses.

How many sources for a literature review?

There are multiple approaches to deciding how many sources to include in a literature review section. The first approach would be to look level you are at as a researcher. For instance, a doctoral thesis might need 60+ sources. In contrast, you might only need to refer to 5-15 sources at the undergraduate level.

The second approach is based on the kind of literature review you are doing — whether it is merely a chapter of your paper or if it is a self-contained paper in itself. When it is just a chapter, sources should equal the total number of pages in your article's body. In the second scenario, you need at least three times as many sources as there are pages in your work.

Quick tips on how to write a literature review

To know how to write a literature review, you must clearly understand its impact and role in establishing your work as substantive research material.

You need to follow the below-mentioned steps, to write a literature review:

• Outline the purpose behind the literature review
• Search relevant literature
• Examine and assess the relevant resources
• Discover connections by drawing deep insights from the resources
• Structure planning to write a good literature review

1. Outline and identify the purpose of  a literature review

As a first step on how to write a literature review, you must know what the research question or topic is and what shape you want your literature review to take. Ensure you understand the research topic inside out, or else seek clarifications. You must be able to the answer below questions before you start:

• How many sources do I need to include?
• What kind of sources should I analyze?
• How much should I critically evaluate each source?
• Should I summarize, synthesize or offer a critique of the sources?
• Do I need to include any background information or definitions?

Additionally, you should know that the narrower your research topic is, the swifter it will be for you to restrict the number of sources to be analyzed.

2. Search relevant literature

Dig deeper into search engines to discover what has already been published around your chosen topic. Make sure you thoroughly go through appropriate reference sources like books, reports, journal articles, government docs, and web-based resources.

You must prepare a list of keywords and their different variations. You can start your search from any library’s catalog, provided you are an active member of that institution. The exact keywords can be extended to widen your research over other databases and academic search engines like:

• Google Scholar
• Microsoft Academic
• Science.gov

Besides, it is not advisable to go through every resource word by word. Alternatively, what you can do is you can start by reading the abstract and then decide whether that source is relevant to your research or not.

Additionally, you must spend surplus time assessing the quality and relevance of resources. It would help if you tried preparing a list of citations to ensure that there lies no repetition of authors, publications, or articles in the literature review.

3. Examine and assess the sources

It is nearly impossible for you to go through every detail in the research article. So rather than trying to fetch every detail, you have to analyze and decide which research sources resemble closest and appear relevant to your chosen domain.

While analyzing the sources, you should look to find out answers to questions like:

• What question or problem has the author been describing and debating?
• What is the definition of critical aspects?
• How well the theories, approach, and methodology have been explained?
• Whether the research theory used some conventional or new innovative approach?
• How relevant are the key findings of the work?
• In what ways does it relate to other sources on the same topic?
• What challenges does this research paper pose to the existing theory
• What are the possible contributions or benefits it adds to the subject domain?

Be always mindful that you refer only to credible and authentic resources. It would be best if you always take references from different publications to validate your theory.

Always keep track of important information or data you can present in your literature review right from the beginning. It will help steer your path from any threats of plagiarism and also make it easier to curate an annotated bibliography or reference section.

4. Discover connections

At this stage, you must start deciding on the argument and structure of your literature review. To accomplish this, you must discover and identify the relations and connections between various resources while drafting your abstract.

A few aspects that you should be aware of while writing a literature review include:

• Rise to prominence: Theories and methods that have gained reputation and supporters over time.
• Constant scrutiny: Concepts or theories that repeatedly went under examination.
• Contradictions and conflicts: Theories, both the supporting and the contradictory ones, for the research topic.
• Knowledge gaps: What exactly does it fail to address, and how to bridge them with further research?
• Influential resources: Significant research projects available that have been upheld as milestones or perhaps, something that can modify the current trends

Once you join the dots between various past research works, it will be easier for you to draw a conclusion and identify your contribution to the existing knowledge base.

5. Structure planning to write a good literature review

There exist different ways towards planning and executing the structure of a literature review. The format of a literature review varies and depends upon the length of the research.

Like any other research paper, the literature review format must contain three sections: introduction, body, and conclusion. The goals and objectives of the research question determine what goes inside these three sections.

Nevertheless, a good literature review can be structured according to the chronological, thematic, methodological, or theoretical framework approach.

Literature review samples

1. Standalone

2. As a section of a research paper

How SciSpace Discover makes literature review a breeze?

SciSpace Discover is a one-stop solution to do an effective literature search and get barrier-free access to scientific knowledge. It is an excellent repository where you can find millions of only peer-reviewed articles and full-text PDF files. Here’s more on how you can use it:

Find the right information

Find what you want quickly and easily with comprehensive search filters that let you narrow down papers according to PDF availability, year of publishing, document type, and affiliated institution. Moreover, you can sort the results based on the publishing date, citation count, and relevance.

Assess credibility of papers quickly

When doing the literature review, it is critical to establish the quality of your sources. They form the foundation of your research. SciSpace Discover helps you assess the quality of a source by providing an overview of its references, citations, and performance metrics.

Get the complete picture in no time

SciSpace Discover’s personalized suggestion engine helps you stay on course and get the complete picture of the topic from one place. Every time you visit an article page, it provides you links to related papers. Besides that, it helps you understand what’s trending, who are the top authors, and who are the leading publishers on a topic.

Make referring sources super easy

To ensure you don't lose track of your sources, you must start noting down your references when doing the literature review. SciSpace Discover makes this step effortless. Click the 'cite' button on an article page, and you will receive preloaded citation text in multiple styles — all you've to do is copy-paste it into your manuscript.

Final tips on how to write a literature review

A massive chunk of time and effort is required to write a good literature review. But, if you go about it systematically, you'll be able to save a ton of time and build a solid foundation for your research.

We hope this guide has helped you answer several key questions you have about writing literature reviews.

Would you like to explore SciSpace Discover and kick off your literature search right away? You can get started here .

Frequently Asked Questions (FAQs)

1. how to start a literature review.

• What questions do you want to answer?

• What sources do you need to answer these questions?

• What information do these sources contain?

• How can you use this information to answer your questions?

2. What to include in a literature review?

• A brief background of the problem or issue

• What has previously been done to address the problem or issue

• A description of what you will do in your project

• How this study will contribute to research on the subject

3. Why literature review is important?

The literature review is an important part of any research project because it allows the writer to look at previous studies on a topic and determine existing gaps in the literature, as well as what has already been done. It will also help them to choose the most appropriate method for their own study.

4. How to cite a literature review in APA format?

To cite a literature review in APA style, you need to provide the author's name, the title of the article, and the year of publication. For example: Patel, A. B., & Stokes, G. S. (2012). The relationship between personality and intelligence: A meta-analysis of longitudinal research. Personality and Individual Differences, 53(1), 16-21

5. What are the components of a literature review?

• A brief introduction to the topic, including its background and context. The introduction should also include a rationale for why the study is being conducted and what it will accomplish.

• A description of the methodologies used in the study. This can include information about data collection methods, sample size, and statistical analyses.

• A presentation of the findings in an organized format that helps readers follow along with the author's conclusions.

6. What are common errors in writing literature review?

• Not spending enough time to critically evaluate the relevance of resources, observations and conclusions.

• Totally relying on secondary data while ignoring primary data.

• Letting your personal bias seep into your interpretation of existing literature.

• No detailed explanation of the procedure to discover and identify an appropriate literature review.

7. What are the 5 C's of writing literature review?

• Cite - the sources you utilized and referenced in your research.

• Compare - existing arguments, hypotheses, methodologies, and conclusions found in the knowledge base.

• Contrast - the arguments, topics, methodologies, approaches, and disputes that may be found in the literature.

• Critique - the literature and describe the ideas and opinions you find more convincing and why.

• Connect - the various studies you reviewed in your research.

8. How many sources should a literature review have?

When it is just a chapter, sources should equal the total number of pages in your article's body. if it is a self-contained paper in itself, you need at least three times as many sources as there are pages in your work.

9. Can literature review have diagrams?

• To represent an abstract idea or concept

• To explain the steps of a process or procedure

• To help readers understand the relationships between different concepts

10. How old should sources be in a literature review?

Sources for a literature review should be as current as possible or not older than ten years. The only exception to this rule is if you are reviewing a historical topic and need to use older sources.

11. What are the types of literature review?

• Argumentative review

• Integrative review

• Methodological review

• Systematic review

• Meta-analysis review

• Historical review

• Theoretical review

• Scoping review

• State-of-the-Art review

12. Is a literature review mandatory?

Yes. Literature review is a mandatory part of any research project. It is a critical step in the process that allows you to establish the scope of your research, and provide a background for the rest of your work.

But before you go,

• Six Online Tools for Easy Literature Review
• Evaluating literature review: systematic vs. scoping reviews
• Systematic Approaches to a Successful Literature Review
• Writing Integrative Literature Reviews: Guidelines and Examples

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Consensus GPT vs. SciSpace GPT: Choose the Best GPT for Research

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• Correction 09 December 2020

How to write a superb literature review

Andy Tay is a freelance writer based in Singapore.

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Literature reviews are important resources for scientists. They provide historical context for a field while offering opinions on its future trajectory. Creating them can provide inspiration for one’s own research, as well as some practice in writing. But few scientists are trained in how to write a review — or in what constitutes an excellent one. Even picking the appropriate software to use can be an involved decision (see ‘Tools and techniques’). So Nature asked editors and working scientists with well-cited reviews for their tips.

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Correction 09 December 2020 : An earlier version of the tables in this article included some incorrect details about the programs Zotero, Endnote and Manubot. These have now been corrected.

Hsing, I.-M., Xu, Y. & Zhao, W. Electroanalysis 19 , 755–768 (2007).

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Ledesma, H. A. et al. Nature Nanotechnol. 14 , 645–657 (2019).

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Brahlek, M., Koirala, N., Bansal, N. & Oh, S. Solid State Commun. 215–216 , 54–62 (2015).

Choi, Y. & Lee, S. Y. Nature Rev. Chem . https://doi.org/10.1038/s41570-020-00221-w (2020).

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Literature Reviews

What this handout is about.

This handout will explain what literature reviews are and offer insights into the form and construction of literature reviews in the humanities, social sciences, and sciences.

Introduction

OK. You’ve got to write a literature review. You dust off a novel and a book of poetry, settle down in your chair, and get ready to issue a “thumbs up” or “thumbs down” as you leaf through the pages. “Literature review” done. Right?

Wrong! The “literature” of a literature review refers to any collection of materials on a topic, not necessarily the great literary texts of the world. “Literature” could be anything from a set of government pamphlets on British colonial methods in Africa to scholarly articles on the treatment of a torn ACL. And a review does not necessarily mean that your reader wants you to give your personal opinion on whether or not you liked these sources.

What is a literature review, then?

A literature review discusses published information in a particular subject area, and sometimes information in a particular subject area within a certain time period.

A literature review can be just a simple summary of the sources, but it usually has an organizational pattern and combines both summary and synthesis. A summary is a recap of the important information of the source, but a synthesis is a re-organization, or a reshuffling, of that information. It might give a new interpretation of old material or combine new with old interpretations. Or it might trace the intellectual progression of the field, including major debates. And depending on the situation, the literature review may evaluate the sources and advise the reader on the most pertinent or relevant.

But how is a literature review different from an academic research paper?

The main focus of an academic research paper is to develop a new argument, and a research paper is likely to contain a literature review as one of its parts. In a research paper, you use the literature as a foundation and as support for a new insight that you contribute. The focus of a literature review, however, is to summarize and synthesize the arguments and ideas of others without adding new contributions.

Why do we write literature reviews?

Literature reviews provide you with a handy guide to a particular topic. If you have limited time to conduct research, literature reviews can give you an overview or act as a stepping stone. For professionals, they are useful reports that keep them up to date with what is current in the field. For scholars, the depth and breadth of the literature review emphasizes the credibility of the writer in his or her field. Literature reviews also provide a solid background for a research paper’s investigation. Comprehensive knowledge of the literature of the field is essential to most research papers.

Who writes these things, anyway?

Literature reviews are written occasionally in the humanities, but mostly in the sciences and social sciences; in experiment and lab reports, they constitute a section of the paper. Sometimes a literature review is written as a paper in itself.

Let’s get to it! What should I do before writing the literature review?

If your assignment is not very specific, seek clarification from your instructor:

• Roughly how many sources should you include?
• What types of sources (books, journal articles, websites)?
• Should you summarize, synthesize, or critique your sources by discussing a common theme or issue?
• Should you evaluate your sources?
• Should you provide subheadings and other background information, such as definitions and/or a history?

Find models

Look for other literature reviews in your area of interest or in the discipline and read them to get a sense of the types of themes you might want to look for in your own research or ways to organize your final review. You can simply put the word “review” in your search engine along with your other topic terms to find articles of this type on the Internet or in an electronic database. The bibliography or reference section of sources you’ve already read are also excellent entry points into your own research.

Narrow your topic

There are hundreds or even thousands of articles and books on most areas of study. The narrower your topic, the easier it will be to limit the number of sources you need to read in order to get a good survey of the material. Your instructor will probably not expect you to read everything that’s out there on the topic, but you’ll make your job easier if you first limit your scope.

Keep in mind that UNC Libraries have research guides and to databases relevant to many fields of study. You can reach out to the subject librarian for a consultation: https://library.unc.edu/support/consultations/ .

And don’t forget to tap into your professor’s (or other professors’) knowledge in the field. Ask your professor questions such as: “If you had to read only one book from the 90’s on topic X, what would it be?” Questions such as this help you to find and determine quickly the most seminal pieces in the field.

Consider whether your sources are current

Some disciplines require that you use information that is as current as possible. In the sciences, for instance, treatments for medical problems are constantly changing according to the latest studies. Information even two years old could be obsolete. However, if you are writing a review in the humanities, history, or social sciences, a survey of the history of the literature may be what is needed, because what is important is how perspectives have changed through the years or within a certain time period. Try sorting through some other current bibliographies or literature reviews in the field to get a sense of what your discipline expects. You can also use this method to consider what is currently of interest to scholars in this field and what is not.

Strategies for writing the literature review

Find a focus.

A literature review, like a term paper, is usually organized around ideas, not the sources themselves as an annotated bibliography would be organized. This means that you will not just simply list your sources and go into detail about each one of them, one at a time. No. As you read widely but selectively in your topic area, consider instead what themes or issues connect your sources together. Do they present one or different solutions? Is there an aspect of the field that is missing? How well do they present the material and do they portray it according to an appropriate theory? Do they reveal a trend in the field? A raging debate? Pick one of these themes to focus the organization of your review.

Convey it to your reader

A literature review may not have a traditional thesis statement (one that makes an argument), but you do need to tell readers what to expect. Try writing a simple statement that lets the reader know what is your main organizing principle. Here are a couple of examples:

The current trend in treatment for congestive heart failure combines surgery and medicine. More and more cultural studies scholars are accepting popular media as a subject worthy of academic consideration.

Consider organization

You’ve got a focus, and you’ve stated it clearly and directly. Now what is the most effective way of presenting the information? What are the most important topics, subtopics, etc., that your review needs to include? And in what order should you present them? Develop an organization for your review at both a global and local level:

First, cover the basic categories

Just like most academic papers, literature reviews also must contain at least three basic elements: an introduction or background information section; the body of the review containing the discussion of sources; and, finally, a conclusion and/or recommendations section to end the paper. The following provides a brief description of the content of each:

• Introduction: Gives a quick idea of the topic of the literature review, such as the central theme or organizational pattern.
• Body: Contains your discussion of sources and is organized either chronologically, thematically, or methodologically (see below for more information on each).
• Conclusions/Recommendations: Discuss what you have drawn from reviewing literature so far. Where might the discussion proceed?

Organizing the body

Once you have the basic categories in place, then you must consider how you will present the sources themselves within the body of your paper. Create an organizational method to focus this section even further.

To help you come up with an overall organizational framework for your review, consider the following scenario:

You’ve decided to focus your literature review on materials dealing with sperm whales. This is because you’ve just finished reading Moby Dick, and you wonder if that whale’s portrayal is really real. You start with some articles about the physiology of sperm whales in biology journals written in the 1980’s. But these articles refer to some British biological studies performed on whales in the early 18th century. So you check those out. Then you look up a book written in 1968 with information on how sperm whales have been portrayed in other forms of art, such as in Alaskan poetry, in French painting, or on whale bone, as the whale hunters in the late 19th century used to do. This makes you wonder about American whaling methods during the time portrayed in Moby Dick, so you find some academic articles published in the last five years on how accurately Herman Melville portrayed the whaling scene in his novel.

Now consider some typical ways of organizing the sources into a review:

• Chronological: If your review follows the chronological method, you could write about the materials above according to when they were published. For instance, first you would talk about the British biological studies of the 18th century, then about Moby Dick, published in 1851, then the book on sperm whales in other art (1968), and finally the biology articles (1980s) and the recent articles on American whaling of the 19th century. But there is relatively no continuity among subjects here. And notice that even though the sources on sperm whales in other art and on American whaling are written recently, they are about other subjects/objects that were created much earlier. Thus, the review loses its chronological focus.
• By publication: Order your sources by publication chronology, then, only if the order demonstrates a more important trend. For instance, you could order a review of literature on biological studies of sperm whales if the progression revealed a change in dissection practices of the researchers who wrote and/or conducted the studies.
• By trend: A better way to organize the above sources chronologically is to examine the sources under another trend, such as the history of whaling. Then your review would have subsections according to eras within this period. For instance, the review might examine whaling from pre-1600-1699, 1700-1799, and 1800-1899. Under this method, you would combine the recent studies on American whaling in the 19th century with Moby Dick itself in the 1800-1899 category, even though the authors wrote a century apart.
• Thematic: Thematic reviews of literature are organized around a topic or issue, rather than the progression of time. However, progression of time may still be an important factor in a thematic review. For instance, the sperm whale review could focus on the development of the harpoon for whale hunting. While the study focuses on one topic, harpoon technology, it will still be organized chronologically. The only difference here between a “chronological” and a “thematic” approach is what is emphasized the most: the development of the harpoon or the harpoon technology.But more authentic thematic reviews tend to break away from chronological order. For instance, a thematic review of material on sperm whales might examine how they are portrayed as “evil” in cultural documents. The subsections might include how they are personified, how their proportions are exaggerated, and their behaviors misunderstood. A review organized in this manner would shift between time periods within each section according to the point made.
• Methodological: A methodological approach differs from the two above in that the focusing factor usually does not have to do with the content of the material. Instead, it focuses on the “methods” of the researcher or writer. For the sperm whale project, one methodological approach would be to look at cultural differences between the portrayal of whales in American, British, and French art work. Or the review might focus on the economic impact of whaling on a community. A methodological scope will influence either the types of documents in the review or the way in which these documents are discussed. Once you’ve decided on the organizational method for the body of the review, the sections you need to include in the paper should be easy to figure out. They should arise out of your organizational strategy. In other words, a chronological review would have subsections for each vital time period. A thematic review would have subtopics based upon factors that relate to the theme or issue.

Sometimes, though, you might need to add additional sections that are necessary for your study, but do not fit in the organizational strategy of the body. What other sections you include in the body is up to you. Put in only what is necessary. Here are a few other sections you might want to consider:

• Current Situation: Information necessary to understand the topic or focus of the literature review.
• History: The chronological progression of the field, the literature, or an idea that is necessary to understand the literature review, if the body of the literature review is not already a chronology.
• Methods and/or Standards: The criteria you used to select the sources in your literature review or the way in which you present your information. For instance, you might explain that your review includes only peer-reviewed articles and journals.

Questions for Further Research: What questions about the field has the review sparked? How will you further your research as a result of the review?

Begin composing

Once you’ve settled on a general pattern of organization, you’re ready to write each section. There are a few guidelines you should follow during the writing stage as well. Here is a sample paragraph from a literature review about sexism and language to illuminate the following discussion:

However, other studies have shown that even gender-neutral antecedents are more likely to produce masculine images than feminine ones (Gastil, 1990). Hamilton (1988) asked students to complete sentences that required them to fill in pronouns that agreed with gender-neutral antecedents such as “writer,” “pedestrian,” and “persons.” The students were asked to describe any image they had when writing the sentence. Hamilton found that people imagined 3.3 men to each woman in the masculine “generic” condition and 1.5 men per woman in the unbiased condition. Thus, while ambient sexism accounted for some of the masculine bias, sexist language amplified the effect. (Source: Erika Falk and Jordan Mills, “Why Sexist Language Affects Persuasion: The Role of Homophily, Intended Audience, and Offense,” Women and Language19:2).

Use evidence

In the example above, the writers refer to several other sources when making their point. A literature review in this sense is just like any other academic research paper. Your interpretation of the available sources must be backed up with evidence to show that what you are saying is valid.

Be selective

Select only the most important points in each source to highlight in the review. The type of information you choose to mention should relate directly to the review’s focus, whether it is thematic, methodological, or chronological.

Use quotes sparingly

Falk and Mills do not use any direct quotes. That is because the survey nature of the literature review does not allow for in-depth discussion or detailed quotes from the text. Some short quotes here and there are okay, though, if you want to emphasize a point, or if what the author said just cannot be rewritten in your own words. Notice that Falk and Mills do quote certain terms that were coined by the author, not common knowledge, or taken directly from the study. But if you find yourself wanting to put in more quotes, check with your instructor.

Summarize and synthesize

Remember to summarize and synthesize your sources within each paragraph as well as throughout the review. The authors here recapitulate important features of Hamilton’s study, but then synthesize it by rephrasing the study’s significance and relating it to their own work.

Keep your own voice

While the literature review presents others’ ideas, your voice (the writer’s) should remain front and center. Notice that Falk and Mills weave references to other sources into their own text, but they still maintain their own voice by starting and ending the paragraph with their own ideas and their own words. The sources support what Falk and Mills are saying.

Use caution when paraphrasing

When paraphrasing a source that is not your own, be sure to represent the author’s information or opinions accurately and in your own words. In the preceding example, Falk and Mills either directly refer in the text to the author of their source, such as Hamilton, or they provide ample notation in the text when the ideas they are mentioning are not their own, for example, Gastil’s. For more information, please see our handout on plagiarism .

Revise, revise, revise

Draft in hand? Now you’re ready to revise. Spending a lot of time revising is a wise idea, because your main objective is to present the material, not the argument. So check over your review again to make sure it follows the assignment and/or your outline. Then, just as you would for most other academic forms of writing, rewrite or rework the language of your review so that you’ve presented your information in the most concise manner possible. Be sure to use terminology familiar to your audience; get rid of unnecessary jargon or slang. Finally, double check that you’ve documented your sources and formatted the review appropriately for your discipline. For tips on the revising and editing process, see our handout on revising drafts .

Works consulted

We consulted these works while writing this handout. This is not a comprehensive list of resources on the handout’s topic, and we encourage you to do your own research to find additional publications. Please do not use this list as a model for the format of your own reference list, as it may not match the citation style you are using. For guidance on formatting citations, please see the UNC Libraries citation tutorial . We revise these tips periodically and welcome feedback.

Anson, Chris M., and Robert A. Schwegler. 2010. The Longman Handbook for Writers and Readers , 6th ed. New York: Longman.

Jones, Robert, Patrick Bizzaro, and Cynthia Selfe. 1997. The Harcourt Brace Guide to Writing in the Disciplines . New York: Harcourt Brace.

Lamb, Sandra E. 1998. How to Write It: A Complete Guide to Everything You’ll Ever Write . Berkeley: Ten Speed Press.

Rosen, Leonard J., and Laurence Behrens. 2003. The Allyn & Bacon Handbook , 5th ed. New York: Longman.

Troyka, Lynn Quittman, and Doug Hesse. 2016. Simon and Schuster Handbook for Writers , 11th ed. London: Pearson.

You may reproduce it for non-commercial use if you use the entire handout and attribute the source: The Writing Center, University of North Carolina at Chapel Hill

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Literature Reviews

• What is a literature review?
• Steps in the Literature Review Process
• Define your research question
• Determine inclusion and exclusion criteria
• Choose databases and search
• Review Results
• Synthesize Results
• Analyze Results
• Librarian Support

What is a Literature Review?

A literature or narrative review is a comprehensive review and analysis of the published literature on a specific topic or research question. The literature that is reviewed contains: books, articles, academic articles, conference proceedings, association papers, and dissertations. It contains the most pertinent studies and points to important past and current research and practices. It provides background and context, and shows how your research will contribute to the field. 

A literature review should: 

• Provide a comprehensive and updated review of the literature;
• Explain why this review has taken place;
• Articulate a position or hypothesis;
• Acknowledge and account for conflicting and corroborating points of view

From  S age Research Methods

Purpose of a Literature Review

A literature review can be written as an introduction to a study to:

• Demonstrate how a study fills a gap in research
• Compare a study with other research that's been done

Or it can be a separate work (a research article on its own) which:

• Organizes or describes a topic
• Describes variables within a particular issue/problem

Limitations of a Literature Review

Some of the limitations of a literature review are:

• It's a snapshot in time. Unlike other reviews, this one has beginning, a middle and an end. There may be future developments that could make your work less relevant.
• It may be too focused. Some niche studies may miss the bigger picture.
• It can be difficult to be comprehensive. There is no way to make sure all the literature on a topic was considered.
• It is easy to be biased if you stick to top tier journals. There may be other places where people are publishing exemplary research. Look to open access publications and conferences to reflect a more inclusive collection. Also, make sure to include opposing views (and not just supporting evidence).

Source: Grant, Maria J., and Andrew Booth. “A Typology of Reviews: An Analysis of 14 Review Types and Associated Methodologies.” Health Information & Libraries Journal, vol. 26, no. 2, June 2009, pp. 91–108. Wiley Online Library, doi:10.1111/j.1471-1842.2009.00848.x.

Meryl Brodsky : Communication and Information Studies

Hannah Chapman Tripp : Biology, Neuroscience

Carolyn Cunningham : Human Development & Family Sciences, Psychology, Sociology

Larayne Dallas : Engineering

Janelle Hedstrom : Special Education, Curriculum & Instruction, Ed Leadership & Policy ​

Susan Macicak : Linguistics

Imelda Vetter : Dell Medical School

For help in other subject areas, please see the guide to library specialists by subject .

Periodically, UT Libraries runs a workshop covering the basics and library support for literature reviews. While we try to offer these once per academic year, we find providing the recording to be helpful to community members who have missed the session. Following is the most recent recording of the workshop, Conducting a Literature Review. To view the recording, a UT login is required.

• October 26, 2022 recording
• Last Updated: Oct 26, 2022 2:49 PM
• URL: https://guides.lib.utexas.edu/literaturereviews

Reference management. Clean and simple.

What is a literature review? [with examples]

What is a literature review?

The purpose of a literature review, how to write a literature review, the format of a literature review, general formatting rules, the length of a literature review, literature review examples, frequently asked questions about literature reviews, related articles.

A literature review is an assessment of the sources in a chosen topic of research.

In a literature review, you’re expected to report on the existing scholarly conversation, without adding new contributions.

If you are currently writing one, you've come to the right place. In the following paragraphs, we will explain:

• the objective of a literature review
• how to write a literature review
• the basic format of a literature review

Tip: It’s not always mandatory to add a literature review in a paper. Theses and dissertations often include them, whereas research papers may not. Make sure to consult with your instructor for exact requirements.

The four main objectives of a literature review are:

• Studying the references of your research area
• Summarizing the main arguments
• Identifying current gaps, stances, and issues
• Presenting all of the above in a text

Ultimately, the main goal of a literature review is to provide the researcher with sufficient knowledge about the topic in question so that they can eventually make an intervention.

The format of a literature review is fairly standard. It includes an:

• introduction that briefly introduces the main topic
• body that includes the main discussion of the key arguments
• conclusion that highlights the gaps and issues of the literature

➡️ Take a look at our guide on how to write a literature review to learn more about how to structure a literature review.

First of all, a literature review should have its own labeled section. You should indicate clearly in the table of contents where the literature can be found, and you should label this section as “Literature Review.”

➡️ For more information on writing a thesis, visit our guide on how to structure a thesis .

There is no set amount of words for a literature review, so the length depends on the research. If you are working with a large amount of sources, it will be long. If your paper does not depend entirely on references, it will be short.

Take a look at these three theses featuring great literature reviews:

• School-Based Speech-Language Pathologist's Perceptions of Sensory Food Aversions in Children [ PDF , see page 20]
• Who's Writing What We Read: Authorship in Criminological Research [ PDF , see page 4]
• A Phenomenological Study of the Lived Experience of Online Instructors of Theological Reflection at Christian Institutions Accredited by the Association of Theological Schools [ PDF , see page 56]

Literature reviews are most commonly found in theses and dissertations. However, you find them in research papers as well.

There is no set amount of words for a literature review, so the length depends on the research. If you are working with a large amount of sources, then it will be long. If your paper does not depend entirely on references, then it will be short.

No. A literature review should have its own independent section. You should indicate clearly in the table of contents where the literature review can be found, and label this section as “Literature Review.”

The main goal of a literature review is to provide the researcher with sufficient knowledge about the topic in question so that they can eventually make an intervention.

Libraries | Research Guides

Literature reviews, what is a literature review, learning more about how to do a literature review.

• Planning the Review
• The Research Question
• Choosing Where to Search
• Organizing the Review
• Writing the Review

A literature review is a review and synthesis of existing research on a topic or research question. A literature review is meant to analyze the scholarly literature, make connections across writings and identify strengths, weaknesses, trends, and missing conversations. A literature review should address different aspects of a topic as it relates to your research question. A literature review goes beyond a description or summary of the literature you have read. 

• Sage Research Methods Core Collection This link opens in a new window SAGE Research Methods supports research at all levels by providing material to guide users through every step of the research process. SAGE Research Methods is the ultimate methods library with more than 1000 books, reference works, journal articles, and instructional videos by world-leading academics from across the social sciences, including the largest collection of qualitative methods books available online from any scholarly publisher. – Publisher

• Next: Planning the Review >>
• Last Updated: Jan 17, 2024 10:05 AM
• URL: https://libguides.northwestern.edu/literaturereviews

How To Structure Your Literature Review

3 options to help structure your chapter.

By: Amy Rommelspacher (PhD) | Reviewer: Dr Eunice Rautenbach | November 2020 (Updated May 2023)

Writing the literature review chapter can seem pretty daunting when you’re piecing together your dissertation or thesis. As  we’ve discussed before , a good literature review needs to achieve a few very important objectives – it should:

• Demonstrate your knowledge of the research topic
• Identify the gaps in the literature and show how your research links to these
• Provide the foundation for your conceptual framework (if you have one)
• Inform your own  methodology and research design

To achieve this, your literature review needs a well-thought-out structure . Get the structure of your literature review chapter wrong and you’ll struggle to achieve these objectives. Don’t worry though – in this post, we’ll look at how to structure your literature review for maximum impact (and marks!).

But wait – is this the right time?

Deciding on the structure of your literature review should come towards the end of the literature review process – after you have collected and digested the literature, but before you start writing the chapter. 

In other words, you need to first develop a rich understanding of the literature before you even attempt to map out a structure. There’s no use trying to develop a structure before you’ve fully wrapped your head around the existing research.

Equally importantly, you need to have a structure in place before you start writing , or your literature review will most likely end up a rambling, disjointed mess. 

Importantly, don’t feel that once you’ve defined a structure you can’t iterate on it. It’s perfectly natural to adjust as you engage in the writing process. As we’ve discussed before , writing is a way of developing your thinking, so it’s quite common for your thinking to change – and therefore, for your chapter structure to change – as you write. 

Need a helping hand?

Like any other chapter in your thesis or dissertation, your literature review needs to have a clear, logical structure. At a minimum, it should have three essential components – an  introduction , a  body   and a  conclusion . 

Let’s take a closer look at each of these.

1: The Introduction Section

Just like any good introduction, the introduction section of your literature review should introduce the purpose and layout (organisation) of the chapter. In other words, your introduction needs to give the reader a taste of what’s to come, and how you’re going to lay that out. Essentially, you should provide the reader with a high-level roadmap of your chapter to give them a taste of the journey that lies ahead.

Here’s an example of the layout visualised in a literature review introduction:

Your introduction should also outline your topic (including any tricky terminology or jargon) and provide an explanation of the scope of your literature review – in other words, what you  will   and  won’t   be covering (the delimitations ). This helps ringfence your review and achieve a clear focus . The clearer and narrower your focus, the deeper you can dive into the topic (which is typically where the magic lies). 

Depending on the nature of your project, you could also present your stance or point of view at this stage. In other words, after grappling with the literature you’ll have an opinion about what the trends and concerns are in the field as well as what’s lacking. The introduction section can then present these ideas so that it is clear to examiners that you’re aware of how your research connects with existing knowledge .

2: The Body Section

The body of your literature review is the centre of your work. This is where you’ll present, analyse, evaluate and synthesise the existing research. In other words, this is where you’re going to earn (or lose) the most marks. Therefore, it’s important to carefully think about how you will organise your discussion to present it in a clear way. 

The body of your literature review should do just as the description of this chapter suggests. It should “review” the literature – in other words, identify, analyse, and synthesise it. So, when thinking about structuring your literature review, you need to think about which structural approach will provide the best “review” for your specific type of research and objectives (we’ll get to this shortly).

There are (broadly speaking)  three options  for organising your literature review.

Option 1: Chronological (according to date)

Organising the literature chronologically is one of the simplest ways to structure your literature review. You start with what was published first and work your way through the literature until you reach the work published most recently. Pretty straightforward.

The benefit of this option is that it makes it easy to discuss the developments and debates in the field as they emerged over time. Organising your literature chronologically also allows you to highlight how specific articles or pieces of work might have changed the course of the field – in other words, which research has had the most impact . Therefore, this approach is very useful when your research is aimed at understanding how the topic has unfolded over time and is often used by scholars in the field of history. That said, this approach can be utilised by anyone that wants to explore change over time .

For example , if a student of politics is investigating how the understanding of democracy has evolved over time, they could use the chronological approach to provide a narrative that demonstrates how this understanding has changed through the ages.

Here are some questions you can ask yourself to help you structure your literature review chronologically.

• What is the earliest literature published relating to this topic?
• How has the field changed over time? Why?
• What are the most recent discoveries/theories?

In some ways, chronology plays a part whichever way you decide to structure your literature review, because you will always, to a certain extent, be analysing how the literature has developed. However, with the chronological approach, the emphasis is very firmly on how the discussion has evolved over time , as opposed to how all the literature links together (which we’ll discuss next ).

Option 2: Thematic (grouped by theme)

The thematic approach to structuring a literature review means organising your literature by theme or category – for example, by independent variables (i.e. factors that have an impact on a specific outcome).

As you’ve been collecting and synthesising literature , you’ll likely have started seeing some themes or patterns emerging. You can then use these themes or patterns as a structure for your body discussion. The thematic approach is the most common approach and is useful for structuring literature reviews in most fields.

For example, if you were researching which factors contributed towards people trusting an organisation, you might find themes such as consumers’ perceptions of an organisation’s competence, benevolence and integrity. Structuring your literature review thematically would mean structuring your literature review’s body section to discuss each of these themes, one section at a time.

Here are some questions to ask yourself when structuring your literature review by themes:

• Are there any patterns that have come to light in the literature?
• What are the central themes and categories used by the researchers?
• Do I have enough evidence of these themes?

PS – you can see an example of a thematically structured literature review in our literature review sample walkthrough video here.

Option 3: Methodological

The methodological option is a way of structuring your literature review by the research methodologies used . In other words, organising your discussion based on the angle from which each piece of research was approached – for example, qualitative , quantitative or mixed  methodologies.

Structuring your literature review by methodology can be useful if you are drawing research from a variety of disciplines and are critiquing different methodologies. The point of this approach is to question  how  existing research has been conducted, as opposed to  what  the conclusions and/or findings the research were.

For example, a sociologist might centre their research around critiquing specific fieldwork practices. Their literature review will then be a summary of the fieldwork methodologies used by different studies.

Here are some questions you can ask yourself when structuring your literature review according to methodology:

• Which methodologies have been utilised in this field?
• Which methodology is the most popular (and why)?
• What are the strengths and weaknesses of the various methodologies?
• How can the existing methodologies inform my own methodology?

3: The Conclusion Section

Once you’ve completed the body section of your literature review using one of the structural approaches we discussed above, you’ll need to “wrap up” your literature review and pull all the pieces together to set the direction for the rest of your dissertation or thesis.

The conclusion is where you’ll present the key findings of your literature review. In this section, you should emphasise the research that is especially important to your research questions and highlight the gaps that exist in the literature. Based on this, you need to make it clear what you will add to the literature – in other words, justify your own research by showing how it will help fill one or more of the gaps you just identified.

Last but not least, if it’s your intention to develop a conceptual framework for your dissertation or thesis, the conclusion section is a good place to present this.

Example: Thematically Structured Review

In the video below, we unpack a literature review chapter so that you can see an example of a thematically structure review in practice.

Let’s Recap

In this article, we’ve  discussed how to structure your literature review for maximum impact. Here’s a quick recap of what  you need to keep in mind when deciding on your literature review structure:

• Just like other chapters, your literature review needs a clear introduction , body and conclusion .
• The introduction section should provide an overview of what you will discuss in your literature review.
• The body section of your literature review can be organised by chronology , theme or methodology . The right structural approach depends on what you’re trying to achieve with your research.
• The conclusion section should draw together the key findings of your literature review and link them to your research questions.

If you’re ready to get started, be sure to download our free literature review template to fast-track your chapter outline.

Psst… there’s more!

This post is an extract from our bestselling short course, Literature Review Bootcamp . If you want to work smart, you don't want to miss this .

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27 Comments

Great work. This is exactly what I was looking for and helps a lot together with your previous post on literature review. One last thing is missing: a link to a great literature chapter of an journal article (maybe with comments of the different sections in this review chapter). Do you know any great literature review chapters?

I agree with you Marin… A great piece

I agree with Marin. This would be quite helpful if you annotate a nicely structured literature from previously published research articles.

Awesome article for my research.

I thank you immensely for this wonderful guide

It is indeed thought and supportive work for the futurist researcher and students

Very educative and good time to get guide. Thank you

Great work, very insightful. Thank you.

Thanks for this wonderful presentation. My question is that do I put all the variables into a single conceptual framework or each hypothesis will have it own conceptual framework?

Thank you very much, very helpful

This is very educative and precise . Thank you very much for dropping this kind of write up .

Pheeww, so damn helpful, thank you for this informative piece.

I’m doing a research project topic ; stool analysis for parasitic worm (enteric) worm, how do I structure it, thanks.

comprehensive explanation. Help us by pasting the URL of some good “literature review” for better understanding.

great piece. thanks for the awesome explanation. it is really worth sharing. I have a little question, if anyone can help me out, which of the options in the body of literature can be best fit if you are writing an architectural thesis that deals with design?

I am doing a research on nanofluids how can l structure it?

Beautifully clear.nThank you!

Lucid! Thankyou!

Brilliant work, well understood, many thanks

I like how this was so clear with simple language 😊😊 thank you so much 😊 for these information 😊

Insightful. I was struggling to come up with a sensible literature review but this has been really helpful. Thank you!

You have given thought-provoking information about the review of the literature.

Thank you. It has made my own research better and to impart your work to students I teach

I learnt a lot from this teaching. It’s a great piece.

I am doing research on EFL teacher motivation for his/her job. How Can I structure it? Is there any detailed template, additional to this?

You are so cool! I do not think I’ve read through something like this before. So nice to find somebody with some genuine thoughts on this issue. Seriously.. thank you for starting this up. This site is one thing that is required on the internet, someone with a little originality!

I’m asked to do conceptual, theoretical and empirical literature, and i just don’t know how to structure it

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English Literature: Resources for Graduate Research

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What is a literature review?

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"A literature review is a body of text that aims to review the critical points of current knowledge on and/or methodological  approaches to a particular topic. They are secondary sources and discuss published information in a particular subject area, and sometimes information in a particular subject area within a certain time period.  Its ultimate goal is to bring the reader up to date with current literature on a topic and forms the basis for another goal, such as future research that may be needed in the area.

A literature review usually precedes a research proposal and may be just a simple summary of sources. Usually, however, it has an organizational pattern and combines both summary and synthesis. 

A summary is a recap of important information about the source, but a synthesis is a re-organization, or a reshuffling, of that information. It might give a new interpretation of old material or combine new with old interpretations. Or it might trace the intellectual progression of the field, including major debates. Depending on the situation, the literature review may evaluate the sources and advise the reader on the most pertinent or relevant of them.

Keep in mind that the main focus of an academic research paper is to develop a new argument, and a research paper will contain a literature review as one of its parts. In a research paper, you use the literature as a foundation and as support for a new insight that you contribute. The focus of a literature review, however, is to summarize and synthesize the arguments and ideas of others without adding new contributions."

The following resource include a number of interesting tips on conducting literature reviews:

• The Literature Review: A Few Tips On Conducting It Valuable guidelines from the University of Toronto.
• Literature Reviews From UNC Chapel Hill, this site explains what literature reviews are and offer insights into the form and construction of literature reviews in the humanities, social sciences, and sciences.
• How to Write a Literature Review A comprehensive guide from UC Santa Cruz Libraries.
• Software Tools for a Literature Review A tutorial that explains how mind maps, pdf readers, and citation managers can be used for a literature review (see first part of the tutorial).
• Review of Literature A useful overview of literature reviews from UW-Madison.
• The Literature Review Ths site was developed by staff at Central Queensland University to help postgraduate students conceptualize, research and write a literature review.

This is a sample of books at Tufts and beyond that include helpful tips for conducting literature reviews and writing dissertations and theses.

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Ten Simple Rules for Writing a Literature Review

Marco pautasso.

1 Centre for Functional and Evolutionary Ecology (CEFE), CNRS, Montpellier, France

2 Centre for Biodiversity Synthesis and Analysis (CESAB), FRB, Aix-en-Provence, France

Literature reviews are in great demand in most scientific fields. Their need stems from the ever-increasing output of scientific publications [1] . For example, compared to 1991, in 2008 three, eight, and forty times more papers were indexed in Web of Science on malaria, obesity, and biodiversity, respectively [2] . Given such mountains of papers, scientists cannot be expected to examine in detail every single new paper relevant to their interests [3] . Thus, it is both advantageous and necessary to rely on regular summaries of the recent literature. Although recognition for scientists mainly comes from primary research, timely literature reviews can lead to new synthetic insights and are often widely read [4] . For such summaries to be useful, however, they need to be compiled in a professional way [5] .

When starting from scratch, reviewing the literature can require a titanic amount of work. That is why researchers who have spent their career working on a certain research issue are in a perfect position to review that literature. Some graduate schools are now offering courses in reviewing the literature, given that most research students start their project by producing an overview of what has already been done on their research issue [6] . However, it is likely that most scientists have not thought in detail about how to approach and carry out a literature review.

Reviewing the literature requires the ability to juggle multiple tasks, from finding and evaluating relevant material to synthesising information from various sources, from critical thinking to paraphrasing, evaluating, and citation skills [7] . In this contribution, I share ten simple rules I learned working on about 25 literature reviews as a PhD and postdoctoral student. Ideas and insights also come from discussions with coauthors and colleagues, as well as feedback from reviewers and editors.

Rule 1: Define a Topic and Audience

How to choose which topic to review? There are so many issues in contemporary science that you could spend a lifetime of attending conferences and reading the literature just pondering what to review. On the one hand, if you take several years to choose, several other people may have had the same idea in the meantime. On the other hand, only a well-considered topic is likely to lead to a brilliant literature review [8] . The topic must at least be:

• interesting to you (ideally, you should have come across a series of recent papers related to your line of work that call for a critical summary),
• an important aspect of the field (so that many readers will be interested in the review and there will be enough material to write it), and
• a well-defined issue (otherwise you could potentially include thousands of publications, which would make the review unhelpful).

Ideas for potential reviews may come from papers providing lists of key research questions to be answered [9] , but also from serendipitous moments during desultory reading and discussions. In addition to choosing your topic, you should also select a target audience. In many cases, the topic (e.g., web services in computational biology) will automatically define an audience (e.g., computational biologists), but that same topic may also be of interest to neighbouring fields (e.g., computer science, biology, etc.).

Rule 2: Search and Re-search the Literature

After having chosen your topic and audience, start by checking the literature and downloading relevant papers. Five pieces of advice here:

• keep track of the search items you use (so that your search can be replicated [10] ),
• keep a list of papers whose pdfs you cannot access immediately (so as to retrieve them later with alternative strategies),
• use a paper management system (e.g., Mendeley, Papers, Qiqqa, Sente),
• define early in the process some criteria for exclusion of irrelevant papers (these criteria can then be described in the review to help define its scope), and
• do not just look for research papers in the area you wish to review, but also seek previous reviews.

The chances are high that someone will already have published a literature review ( Figure 1 ), if not exactly on the issue you are planning to tackle, at least on a related topic. If there are already a few or several reviews of the literature on your issue, my advice is not to give up, but to carry on with your own literature review,

The bottom-right situation (many literature reviews but few research papers) is not just a theoretical situation; it applies, for example, to the study of the impacts of climate change on plant diseases, where there appear to be more literature reviews than research studies [33] .

• discussing in your review the approaches, limitations, and conclusions of past reviews,
• trying to find a new angle that has not been covered adequately in the previous reviews, and
• incorporating new material that has inevitably accumulated since their appearance.

When searching the literature for pertinent papers and reviews, the usual rules apply:

• be thorough,
• use different keywords and database sources (e.g., DBLP, Google Scholar, ISI Proceedings, JSTOR Search, Medline, Scopus, Web of Science), and
• look at who has cited past relevant papers and book chapters.

Rule 3: Take Notes While Reading

If you read the papers first, and only afterwards start writing the review, you will need a very good memory to remember who wrote what, and what your impressions and associations were while reading each single paper. My advice is, while reading, to start writing down interesting pieces of information, insights about how to organize the review, and thoughts on what to write. This way, by the time you have read the literature you selected, you will already have a rough draft of the review.

Of course, this draft will still need much rewriting, restructuring, and rethinking to obtain a text with a coherent argument [11] , but you will have avoided the danger posed by staring at a blank document. Be careful when taking notes to use quotation marks if you are provisionally copying verbatim from the literature. It is advisable then to reformulate such quotes with your own words in the final draft. It is important to be careful in noting the references already at this stage, so as to avoid misattributions. Using referencing software from the very beginning of your endeavour will save you time.

Rule 4: Choose the Type of Review You Wish to Write

After having taken notes while reading the literature, you will have a rough idea of the amount of material available for the review. This is probably a good time to decide whether to go for a mini- or a full review. Some journals are now favouring the publication of rather short reviews focusing on the last few years, with a limit on the number of words and citations. A mini-review is not necessarily a minor review: it may well attract more attention from busy readers, although it will inevitably simplify some issues and leave out some relevant material due to space limitations. A full review will have the advantage of more freedom to cover in detail the complexities of a particular scientific development, but may then be left in the pile of the very important papers “to be read” by readers with little time to spare for major monographs.

There is probably a continuum between mini- and full reviews. The same point applies to the dichotomy of descriptive vs. integrative reviews. While descriptive reviews focus on the methodology, findings, and interpretation of each reviewed study, integrative reviews attempt to find common ideas and concepts from the reviewed material [12] . A similar distinction exists between narrative and systematic reviews: while narrative reviews are qualitative, systematic reviews attempt to test a hypothesis based on the published evidence, which is gathered using a predefined protocol to reduce bias [13] , [14] . When systematic reviews analyse quantitative results in a quantitative way, they become meta-analyses. The choice between different review types will have to be made on a case-by-case basis, depending not just on the nature of the material found and the preferences of the target journal(s), but also on the time available to write the review and the number of coauthors [15] .

Rule 5: Keep the Review Focused, but Make It of Broad Interest

Whether your plan is to write a mini- or a full review, it is good advice to keep it focused 16 , 17 . Including material just for the sake of it can easily lead to reviews that are trying to do too many things at once. The need to keep a review focused can be problematic for interdisciplinary reviews, where the aim is to bridge the gap between fields [18] . If you are writing a review on, for example, how epidemiological approaches are used in modelling the spread of ideas, you may be inclined to include material from both parent fields, epidemiology and the study of cultural diffusion. This may be necessary to some extent, but in this case a focused review would only deal in detail with those studies at the interface between epidemiology and the spread of ideas.

While focus is an important feature of a successful review, this requirement has to be balanced with the need to make the review relevant to a broad audience. This square may be circled by discussing the wider implications of the reviewed topic for other disciplines.

Rule 6: Be Critical and Consistent

Reviewing the literature is not stamp collecting. A good review does not just summarize the literature, but discusses it critically, identifies methodological problems, and points out research gaps [19] . After having read a review of the literature, a reader should have a rough idea of:

• the major achievements in the reviewed field,
• the main areas of debate, and
• the outstanding research questions.

It is challenging to achieve a successful review on all these fronts. A solution can be to involve a set of complementary coauthors: some people are excellent at mapping what has been achieved, some others are very good at identifying dark clouds on the horizon, and some have instead a knack at predicting where solutions are going to come from. If your journal club has exactly this sort of team, then you should definitely write a review of the literature! In addition to critical thinking, a literature review needs consistency, for example in the choice of passive vs. active voice and present vs. past tense.

Rule 7: Find a Logical Structure

Like a well-baked cake, a good review has a number of telling features: it is worth the reader's time, timely, systematic, well written, focused, and critical. It also needs a good structure. With reviews, the usual subdivision of research papers into introduction, methods, results, and discussion does not work or is rarely used. However, a general introduction of the context and, toward the end, a recapitulation of the main points covered and take-home messages make sense also in the case of reviews. For systematic reviews, there is a trend towards including information about how the literature was searched (database, keywords, time limits) [20] .

How can you organize the flow of the main body of the review so that the reader will be drawn into and guided through it? It is generally helpful to draw a conceptual scheme of the review, e.g., with mind-mapping techniques. Such diagrams can help recognize a logical way to order and link the various sections of a review [21] . This is the case not just at the writing stage, but also for readers if the diagram is included in the review as a figure. A careful selection of diagrams and figures relevant to the reviewed topic can be very helpful to structure the text too [22] .

Rule 8: Make Use of Feedback

Reviews of the literature are normally peer-reviewed in the same way as research papers, and rightly so [23] . As a rule, incorporating feedback from reviewers greatly helps improve a review draft. Having read the review with a fresh mind, reviewers may spot inaccuracies, inconsistencies, and ambiguities that had not been noticed by the writers due to rereading the typescript too many times. It is however advisable to reread the draft one more time before submission, as a last-minute correction of typos, leaps, and muddled sentences may enable the reviewers to focus on providing advice on the content rather than the form.

Feedback is vital to writing a good review, and should be sought from a variety of colleagues, so as to obtain a diversity of views on the draft. This may lead in some cases to conflicting views on the merits of the paper, and on how to improve it, but such a situation is better than the absence of feedback. A diversity of feedback perspectives on a literature review can help identify where the consensus view stands in the landscape of the current scientific understanding of an issue [24] .

Rule 9: Include Your Own Relevant Research, but Be Objective

In many cases, reviewers of the literature will have published studies relevant to the review they are writing. This could create a conflict of interest: how can reviewers report objectively on their own work [25] ? Some scientists may be overly enthusiastic about what they have published, and thus risk giving too much importance to their own findings in the review. However, bias could also occur in the other direction: some scientists may be unduly dismissive of their own achievements, so that they will tend to downplay their contribution (if any) to a field when reviewing it.

In general, a review of the literature should neither be a public relations brochure nor an exercise in competitive self-denial. If a reviewer is up to the job of producing a well-organized and methodical review, which flows well and provides a service to the readership, then it should be possible to be objective in reviewing one's own relevant findings. In reviews written by multiple authors, this may be achieved by assigning the review of the results of a coauthor to different coauthors.

Rule 10: Be Up-to-Date, but Do Not Forget Older Studies

Given the progressive acceleration in the publication of scientific papers, today's reviews of the literature need awareness not just of the overall direction and achievements of a field of inquiry, but also of the latest studies, so as not to become out-of-date before they have been published. Ideally, a literature review should not identify as a major research gap an issue that has just been addressed in a series of papers in press (the same applies, of course, to older, overlooked studies (“sleeping beauties” [26] )). This implies that literature reviewers would do well to keep an eye on electronic lists of papers in press, given that it can take months before these appear in scientific databases. Some reviews declare that they have scanned the literature up to a certain point in time, but given that peer review can be a rather lengthy process, a full search for newly appeared literature at the revision stage may be worthwhile. Assessing the contribution of papers that have just appeared is particularly challenging, because there is little perspective with which to gauge their significance and impact on further research and society.

Inevitably, new papers on the reviewed topic (including independently written literature reviews) will appear from all quarters after the review has been published, so that there may soon be the need for an updated review. But this is the nature of science [27] – [32] . I wish everybody good luck with writing a review of the literature.

Acknowledgments

Many thanks to M. Barbosa, K. Dehnen-Schmutz, T. Döring, D. Fontaneto, M. Garbelotto, O. Holdenrieder, M. Jeger, D. Lonsdale, A. MacLeod, P. Mills, M. Moslonka-Lefebvre, G. Stancanelli, P. Weisberg, and X. Xu for insights and discussions, and to P. Bourne, T. Matoni, and D. Smith for helpful comments on a previous draft.

Funding Statement

This work was funded by the French Foundation for Research on Biodiversity (FRB) through its Centre for Synthesis and Analysis of Biodiversity data (CESAB), as part of the NETSEED research project. The funders had no role in the preparation of the manuscript.

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Literature review vs research articles: how are they different.

Unlock the secrets of academic writing with our guide to the key differences between a literature review and a research paper! 📚 Dive into the world of scholarly exploration as we break down how a literature review illuminates existing knowledge, identifies gaps, and sets the stage for further research. 🌐 Then, gear up for the adventure of crafting a research paper, where you become the explorer, presenting your unique insights and discoveries through independent research. 🚀 Join us on this academic journey and discover the art of synthesizing existing wisdom and creating your own scholarly masterpiece! 🎓✨

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Peer-reviewed

Research Article

Echogenic intracardiac foci detection and location in the second-trimester ultrasound and association with fetal outcomes: A systematic literature review

Roles Formal analysis, Investigation, Validation, Visualization, Writing – original draft, Writing – review & editing

* E-mail: [email protected]

Affiliation National Centre for Population Health and Wellbeing Research, Swansea, United Kingdom

Roles Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Visualization, Writing – original draft, Writing – review & editing

Affiliation Swansea University, Sketty, Swansea, United Kingdom

Roles Data curation, Formal analysis, Writing – review & editing

Affiliation Cardiff University, University Hospital of Wales, Cardiff, United Kingdom

Roles Writing – review & editing

Affiliation Cardiff and Vale UHB: NHS Wales Cardiff and Vale University Health Board, Children’s Heart Unit, Cardiff, United Kingdom

Roles Formal analysis, Investigation, Methodology, Project administration, Visualization, Writing – original draft, Writing – review & editing

• Hope Eleri Jones, 
• Serica Battaglia, 
• Lisa Hurt, 
• Orhan Uzun, 
• Sinead Brophy

• Published: April 22, 2024
• https://doi.org/10.1371/journal.pone.0298365
• Peer Review
• Reader Comments

Echogenic Intracardiac Foci (EIF) are non-structural markers identified during the routine 18–20-week foetal anomaly ultrasound scan yet their clinical significance on future outcomes for the infant is unclear.

To examine the association between EIF and risk of preterm birth, chromosomal abnormalities, and cardiac abnormalities.

A review across four databases to identify English language journal articles of EIF using a cohort study design. All studies were reviewed for quality using the Critical Appraisal Skills Programme (CASP) checklist and data extracted for comparison and analysis.

19 papers from 9 different countries were included. Combining these studies showed 4.6% (95% CI = 4.55–4.65%) of all pregnancies had EIF which was on the left in 86% of cases, on the right in 3% of cases and bilaterally in 10%. There was no evidence that EIF was associated with higher rates of preterm birth. However, it is possible that infants with EIF were more likely to be terminated rather than be born preterm as there was a 2.1% (range 0.3–4.2%) rate of termination or death of the foetus after week 20 among those with EIF. There was no evidence that EIF alone is highly predictive of chromosomal abnormalities. There was evidence that EIF is associated with higher rates of minor cardiac abnormalities (e.g. ventricular septal defect, tricuspid regurgitation or mitral regurgitation)) with 5.1% (224 of 4385) of those with EIF showing cardiac abnormalities (3.08% in retrospective studies and 17.85% in prospective studies). However, the risk of cardiac defects was only higher with right-sided EIF and where the EIF persisted into the third trimester. However, this is a rare event and would be seen in an estimated 4 per 10,000 pregnancies.

EIF alone was not associated with adverse outcomes for the infant. Only persistent EIF on the right side showed evidence of carrying a higher risk of cardiac abnormality and would warrant further follow-up.

Citation: Jones HE, Battaglia S, Hurt L, Uzun O, Brophy S (2024) Echogenic intracardiac foci detection and location in the second-trimester ultrasound and association with fetal outcomes: A systematic literature review. PLoS ONE 19(4): e0298365. https://doi.org/10.1371/journal.pone.0298365

Editor: Mateen A. Khan, Alfaisal University, SAUDI ARABIA

Received: October 26, 2023; Accepted: January 24, 2024; Published: April 22, 2024

Copyright: © 2024 Jones et al. This is an open access article distributed under the terms of the Creative Commons Attribution License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Data Availability: This is a literature review so the relevant data is in each of the papers mentioned in the review that are all open access. The values behind the measures reported and used to build graphs and figures are provided in the supplementary information .

Funding: The author(s) received no specific funding for this work.

Competing interests: The authors have declared that no competing interests exist.

Introduction

Congenital heart disease (CHD) is characterised by defects in the heart as it forms in the growing foetus [ 1 ]. CHD is the most common congenital abnormality in infants today with a diagnosis made 1 in every 100 births [ 2 , 3 ]. CHD is the leading cause of infant mortality [ 3 , 4 ]. Improvements in early detection and diagnosis would greatly improve the support and service provision for families when the infant is born, developing early preventative interventions, and putting in place enhanced monitoring and care for the infant.

A foetal anomaly scan is offered to all pregnant women in the UK between weeks 18-to-20 of pregnancy which includes routine screening for CHD [ 5 , 6 ]. However, it is estimated that only 50% - 75% of cases of serious congenital cardiac abnormalities are detected during this scan [ 5 ]. Potential discrepancies may be due to variations in equipment and facilities available to undertake the appropriate level of screening [ 7 ]. The extensive use and improvements to ultrasound imaging has enabled more detailed detection of fetal structural variations alongside the identification of more subtle non-structural findings, labelled as markers [ 7 – 9 ]. This has led to the identification of ultrasound soft markers (USM) [ 10 ], including Echogenic Intracardiac Foci (EIF), which are often discovered as an incidental finding during prenatal screening [ 11 ].

EIF have been described as small echogenic areas of microcalcification or fibrosis on the papillary muscle of either or both atrioventricular valves of the foetal heart [ 12 ]. EIF are often referred to as echo bright spots or hyper echogenicity of foetal soft tissue [ 13 , 14 ] when visualised on a foetal ultrasound. They are of equal or greater brightness than the surrounding bone [ 15 , 16 ]. The pathological cause of EIF remains ambiguous and it is still unclear what is the significance, if any, in terms of defects in the developing heart of the foetus. Research has suggested that EIF prevalence during this second-trimester scan is estimated to occur in between 0.17% and 20% of pregnancies [ 7 ]. The prevalence varies by race, with the highest incidence found amongst Asian populations [ 17 ].

Previous research has described EIF as often transient, resolving by the third trimester of pregnancy or after delivery [ 18 ], nonpathological or benign in isolation [ 11 ], and therefore has been highlighted that isolated soft markers may be present in 10% of normal foetuses [ 19 ]. However, multiple USM and the presence of specific soft markers, in terms of the specific location and size, may be associated with underlying chromosomal abnormalities (such as an association between the presence of EIF and a later diagnosis of Down’s syndrome) albeit the current evidence is not supportive of this [ 20 ] or adverse infant outcomes [ 21 ]. This suggests that the presence of specific soft markers may be associated with structural abnormalities and developmental conditions [ 22 ].

Given that EIF are small structures within the foetal ventricle chamber, they have been commonly associated with other soft markers [ 19 ]. However, it is unclear whether EIF can be used as a screening tool for cardiac heart diseases as previous research has shown mixed results. Despite the possible concerns surrounding the association between the development of structural and chromosomal abnormalities in the affected foetus, available data is debatable and inconclusive in some publications whilst others clearly showed no significance.

The presence of EIF with additional risk factors such as older maternal age (>35 years) places the mother in a high-risk category [ 22 ] during the pregnancy. Depending on the association with other soft markers this may lead to a referral for an echocardiogram and/or genetic counselling for amniocentesis to investigate possible chromosomal abnormalities. If EIF persists until birth and is present alongside other soft markers, a postnatal echocardiogram would be recommended and a referral to neonatal consultant. However, with increasing maternal age [ 23 ] and improvements in ultrasound detection [ 9 ] this is becoming more common therefore adding to costs of healthcare, potentially with little gain as the prevalence of congenital abnormality has remained constant [ 24 ].

It remains unclear whether EIF encompasses both benign transient structural variations and pathological changes [ 18 , 22 ]. Distinguishing between these two would be significant in terms of determining those to take forward for echocardiography and this is especially important in times of financial strain on the NHS. It is unclear whether location of EIF and number of EIFs are of more significance rather than their presence or absence.

The aim of this literature review is to examine the association between EIF and infant outcomes. Specifically: 1) The association between EIF identified at 18–20 weeks and risk of preterm birth, death, specific cardiac diagnosis (CHD) and chromosomal abnormalities. 2) The association between the number of EIF (single vs multiple), the location of EIF (left, right or bilateral) and the risk of preterm birth, death, cardiac diagnosis, and chromosomal abnormalities.

This review follows the Population-Interest-Comparator-Outcome (PICO) criteria to guide the scope and breadth of the literature review and set the inclusion criteria. The population was defined as the foetus at the 18–20-week ultrasound scan. The interest was where EIF was identified in the scan (as identified by the sonographer) compared to the comparator of those with no EIF. The infant outcomes include preterm delivery, death, structural cardiac abnormality, and chromosomal abnormalities.

Inclusion criteria

Peer-reviewed cohort studies in English, with full-text availability, published between 2013–2023. Studies included prospective and retrospective cohort studies with the assessment of EIF (with or without other markers) recorded by ultrasound at 18–20 weeks gestation and recording through follow-up (e.g., birth and post birth up to 5 years) with one of the outcome variables of interest. Studies which contain follow-up data to birth and infancy following assessment of routine ultrasound screening in a healthcare setting in the second trimester of pregnancy were included. Studies that only followed up EIF pregnancies without a comparison group were included in selected studies. However, if selection bias was present (e.g., only women >35 years) this was recorded in the data quality assessment and incorporated into the interpretation.

Exclusion criteria

Studies were excluded if the full text was not available in English, they examined non-cardiac echogenic focus (e.g. identified within the kidneys, liver, bowel, thyroid, hepatic, and pancreas). Also excluded were those not performed during the second-trimester ultrasound scan or those studies predicting echogenic foci as the outcome rather than the exposure.

Outcome measures

The primary outcome measure is preterm birth (before 37 weeks) or death of the foetus. Secondary outcomes include chromosomal abnormality (genetic testing for aneuploidy, amniocentesis or NIPT (Non-Invasive Prenatal testing) reports) and cardiac abnormality (fetal echocardiology reports and/or postnatal diagnosis).

Literature search

The literature search was carried out in three stages: Stage one was an initial search on Pubmed to identify the index terms which best identify relevant articles. This initial search used the first 10 relevant primary studies and collated the search terms that were used. The second stage took these updated search terms to apply to the; Web of Science online tool which searches the following databases: Web of Science Core Collection, BIOSIS Citation Index, Current Contents Connects, Data Citation Index, Derwent Innovations Index, and MEDLINE (Medical Literature Analysis and Retrieval System Online). This search was repeated on Pubmed and Scopus individually. The final stage reviewed the reference list of the included studies and reviews in the area. Grey literature was also reviewed including the National Congenital Heart Disease Audit (NCHDA). The literature search was carried out in June 2023 and imported onto Covidence software [ 25 ]. The keywords identified for the initial search included: Echogenic intracardiac foci, Chromosomal abnormalities, Prenatal diagnosis, Ultrasonography, Echocardiography, Pregnancy trimester second, Foetal cardiac anomalies OR foetal cardiac abnormalities, Foetal echocardiography, Foetal heart, Trisomy 21 (Down syndrome), Prenatal screening and Pregnancy outcomes. The search terms used to identify relevant papers consisted of four concepts and were combined to form the following search string across all key databases: “echogenic intracardiac foc*” OR “echogenic foc*” OR “intracardiac foc*” OR “cardiac echogenic foc*”.

Study selection

Covidence automatically removes duplicate records [ 25 ]. Initial screening based on the title and abstract was carried out by two independent reviewers based on the inclusion and exclusion criteria. For those publications selected to take forward, a second screening based on the full text was conducted and those selected as relevant were taken forward to data extraction ( Fig 1 ).

• PPT PowerPoint slide
• PNG larger image
• TIFF original image

https://doi.org/10.1371/journal.pone.0298365.g001

Extraction of relevant variables

A data extraction form was designed which included the Critical Appraisal Skills Programme (CASP) quality review [ 26 ] to assess risk of bias. Quality was assessed to include methods of addressing confounding variables, quality of measurement of outcome and exposure and if outcomes by exposure and loss to follow-up. The data includes study identification (number, first author), study demographic information (country, size of study, study design), total number of pregnancies, number with EIF recorded, duration of follow up, recording of outcomes of interest, position (left/right) of EIF and number of EIF (single/multiple). See the supplementary information for details of extracted variables, definitions and how they were recorded ( S1 Table ).

Comparison data

The outcomes for those with no EIF were recorded in the same way as those with EIF reporting the number of preterm births, deaths, congenital abnormalities and cardiac abnormalities.

There were 243 non-duplicate studies that were identified using the search criteria. Of these, 206 were excluded at the title and abstract screening due to studies being published before 2013, not a study examining EIF (e.g., assessing cysts or other soft markers) and non-English studies. 35 full journal articles were reviewed. However, the majority were excluded on the basis that they did not have a cohort design (health economics study or case study or case series), did not have follow-up of those with EIF, or did not have follow up of the outcomes which were considered within this review. After full text review, 19 studies were included ( Fig 2 ). These 19 studies covered 9 different countries with 9 of the studies from China, 2 from Iran and 2 from Pakistan. The smallest study had a follow-up of 7 EIF pregnancies and the largest was 143,067 pregnancies of which 2647 had EIF. 6 studies had prospective follow-up of infants and the remaining 13 had retrospective follow-up using routine medical records.

https://doi.org/10.1371/journal.pone.0298365.g002

The majority of studies were rated as being of moderate quality as there was missing data, or loss to follow-up, especially in the prospective studies. For example, a postpartum follow-up study was performed on women referred for echocardiography and of these 7 had EIF [ 1 ]. This study was rated as high risk of selection bias and so rated moderate. Another study was rated moderate as there was loss to follow-up among some EIF participants [ 27 ]. Other studies were not stratified by EIF characteristics making interpretation difficult and therefore rated low [ 28 ]. Moreover, in some cases the dates of recruitment were not being reported, and it was unclear how many terminations of pregnancies occurred [ 29 ]. Overall, the study quality was rated as moderate and there was a risk of bias such as loss to follow-up or selection bias in various papers.

EIF association with outcomes

This review followed 34,104 women from 19 studies (4 studies did not provide a total number of women screened). Of these, there were 15,600 EIFs or 4.6% (95% CI = 4.55–4.65%) of all pregnancies and 4.5% (range 0.5% to 17.8%) of pregnancies when the EIF proportion of each study was averaged. This highlights that EIF is a relatively common finding on ultrasound scans. In addition, 5 studies followed-up those with EIF only (e.g. a cohort of those with EIF) which identified an additional 1,400 EIFs for follow-up. On average, 26.6% presented with multiple EIFs and the remaining had a single EIF. Taking the averaged levels in each study (6 studies reporting the location of EIF), the EIF was on the left side in 86% of cases, on the right in 3%, and bilaterally in 10%. Therefore, EIF on the right is a rare occurrence that only occurred in 13% of EIFs or 6 per 1000 pregnancies.

Preterm births

Five studies reported the rates of preterm birth where the prevalence was 7.2% (range 2–13%). This rate is comparable to the UK where the preterm rate is 7.8% (23) compared to 13% in North Africa [ 30 ] In two studies that reported preterm rates among non-EIF pregnancies, the range was between 5–20%. Comparing the two papers that reported EIF and non-EIF preterm rates, there was no evidence that EIF is associated with preterm birth with 4.8% (EIF) versus 5.1% (non-EIF) in Wales with the sample size 18,841 EIF (N = 858) [ 31 ], and 13.0% (EIF) versus 20.9% (non-EIF) [ 32 ] with the sample size 9,270 (EIF = 230) in Lebanon. This follow-up in a total of 5 studies (2 with control data) does not provide evidence of higher preterm rates in those with EIF. However, in the study in the UK [ 31 ], the authors had the scans reviewed by a quality assurance panel and of the 858 EIF scans only 615 were assessed by the quality assurance panel as EIF’s. This means that there were 44 preterm births out of 615 with EIF (7.2%) which is in line with population level preterm rates in Wales [ 23 ]. The non EIF was 921 preterm births out of 18,226 pregnancies without EIF (5.1%).

However, it is possible that infants with EIF were more likely to be foetal deaths or termination rather than being born preterm. There was a 2.0% (range 0.3–4.2%) rate of termination or death of the foetus after week 20, among those with EIF. This rate is higher than previously reported [ 33 ] which suggests that less than 0.5% of pregnancies will end in foetal death after 20 weeks. The main cause of death in China and Iran appears to be termination due to suggested chromosomal abnormalities and other soft markers. For example, pregnancies were terminated due to abnormal chromosome numbers (35)(28) and 50% of deaths had chromosomal abnormalities [ 19 ]. Many pregnant women with EIF had invasive foetal testing to screen for chromosomal abnormalities [ 28 ]. The findings presented that the increase in the risk of chromosomal abnormalities in the foetus was related to the pregnant women belonging to high-risk groups, rather than EIF [ 28 ].

In Wales, foetal deaths (0.48% of confirmed EIF pregnancies) were due to stillbirths and induced or spontaneous pregnancy loss. This rate of foetal death is in line with expected rates and comparable to non-EIF rates. In Lebanon, foetal deaths (0.9%) were due to foetal demise but this was at the expected rate and equivalent to non-EIF foetal loss rates. In Pakistan, the deaths were associated with cases of pulmonary artery hypertension and tetralogy of Fallot and were all neonatal deaths ( Fig 3 ). This was a higher-than-expected rate, but the sample size was small.

https://doi.org/10.1371/journal.pone.0298365.g003

Overall, there was no evidence that preterm rates were higher among those with EIF. Terminations were higher in China and Iran, and these were associated with chromosomal abnormalities. The rate of foetal death was not higher in countries like Wales or Lebanon with different health care practices and where invasive foetal testing is not performed when EIF is detected.

Chromosomal abnormalities

Ten studies [ 18 , 19 , 22 , 27 , 31 , 32 , 34 – 37 ] reported chromosomal abnormalities and the rate of abnormalities was 1.98% (range 0–5.7%) among those with EIF. The chromosomal abnormalities identified with EIF were Trisomy 18, 46, 21 XXY, XYY and Turner’s syndrome. Three studies also reported abnormalities among those without EIF and in each of these studies the internal comparison of abnormality rate between EIF and non-EIF suggested no higher rate of chromosomal abnormalities among those with EIF ( Fig 4 ). The sample size of EIF pregnancies were 58 in Ko et al. [ 22 ], 1099 in Wang et al. [ 18 ] and 230 in Mirza et al. [ 32 ].

https://doi.org/10.1371/journal.pone.0298365.g004

Cardiac abnormalities

Cardiac abnormalities were reported in 10 studies [ 1 , 3 , 14 , 15 , 27 , 34 , 37 – 39 ] and the average for all studies was 8.2% (range 1.8% to 39%). When all findings were combined there was a 5.1% rate (224/4385) ( Fig 5 ). The retrospective cohort study findings gave a rate of 3.3% and the prospective studies (with higher rates of missing data and loss to follow-up) was 17.85%. Abnormalities included VSD, tricuspid regurgitation and mitral regurgitation. Two studies reported cardiac abnormalities in non-EIF pregnancies, which ranged from 1.5–3.1%. CHD is thought to affect about <1% of births [ 40 ]. There does appear to be evidence that EIF is associated with higher rates of cardiac abnormality (e.g. 3.3% (95%CI 1.1–5.6) rate of cardiac abnormality). However, it remains that 97% of those detected with EIF will not have a cardiac abnormality. Specific findings from the included studies are available in the supplementary information ( S2 Table ).

https://doi.org/10.1371/journal.pone.0298365.g005

Location of EIF

The location of the EIF was recorded in 6 studies. However, follow-up of proportion with a cardiac abnormality by EIF location was only recorded in three studies [ 14 , 15 , 39 ]. Combining the findings for left EIF compared to right EIF showed 7.9% (6/76) (95% CI: 2.9%-16.4%) of right EIF were associated with cardiac abnormality compared to 3.6% (107/2,992) (95% CI: 2.9%-4.3%) in the left (difference: 4.3% (95%CI: 0.03% to 12.6%)) showing higher rates with right-sided EIF compared to the left [ 14 , 15 , 39 ]. The rate of abnormality in bilateral EIF did not differ from the rate seen in the left EIF. The findings from Chiu [ 39 ] suggested persistent EIF into the third trimester may be associated with higher risk of congenital heart defects such as VSD. Therefore, the follow up of EIF later in pregnancy may be useful to examine if the EIF resolves or persists.

In summary, a EIF in the right ventricle may not resolve as often as that in the left and combining the findings from studies suggested that an EIF in the right is associated with higher rates of cardiac abnormality (7.9% rate if EIF at 20 weeks but this could be higher if persistent beyond 20 weeks). There is ethnic variation in the prevalence of EIF and therefore there is likely to be ethnic variation in the significance of EIF. Only an EIF observed in the third trimester on the right may be associated with cardiac abnormality. However, this would be only 4 per 10,000 pregnancies who would have a right EIF which did not resolve by the third trimester (e.g. 4.5 pregnancies have an EIF, 3% of these are on the right (13.5 per 10,000) and of these 30% persist to third trimester or 4 per 10,000 pregnancies have a persistent EIF on the right). Therefore, EIF in general, is unlikely to be significant as a predictive or screening tool.

Findings from this review highlight that only if the EIF is on the right side and persists until the third trimester, is there a higher chance of cardiac abnormalities (7% risk of cardiac abnormality at 20-week scan), and only in these persistent cases could it be advised that there should be further investigation. This finding that the EIF is not predictive of poor outcomes is significant, especially given the current post COVID-19 strains on health systems worldwide. It must be noted that this data is for isolated markers. There is clear and consistent data that multiple markers are associated with adverse outcomes.

Supportive evidence in terms of the risk of aneuploidy reported that isolated EIF is considered an incidental finding and does not warrant amniocentesis, but that amniocentesis should be undertaken in high-risk cases where other soft markers are identified or there is a history of chromosomal abnormalities in previous pregnancies [ 38 ]. A meta-analysis for the risk of Down’s Syndrome suggests that EIF increases the risk by 5–7 folds [ 41 ]. In contrast, an association between EIF and Trisomy 21 is not always reported [ 42 ]. The Society for Foetal Medicine [ 17 ] recommends that for those with no previous aneuploid screening and have an isolated EIF, there should be genetic counseling to estimate the probability of Trisomy 21 and discussion on options for non-invasive screening.

Findings from this review suggest that an isolated EIF would not warrant further investigation, that multiple foci do not carry a higher risk compared to single foci, and that recommendations to follow-up should be based on other risk factors (e.g., maternal age, family history) rather than the presence of EIF without other soft markers. It was found that there were higher terminations in countries like China where many pregnant women with EIF have invasive tests to screen for abnormalities. This suggests that EIF in these countries may be randomly associated with or a consequence of chromosomal abnormalities rather than being a marker for it or that simply the perceived risk of future abnormalities is enough to lead to a termination. The majority of infants terminated in these studies had Variants of Uncertain Significance (VOUS) and so may have been healthy. In countries where the presence of EIF does not lead to chromosomal testing there was no evidence of higher rates of death among infants with EIF. In low-risk pregnancies with EIF, invasive chromosomal testing may lead to harm, such as an increased abortion rate, and is unlikely to lead to benefits of increased detection of chromosomal abnormalities.

VSD was associated with EIF in some studies [ 1 , 14 , 15 , 27 , 29 , 34 , 38 , 39 ] but this association can also be random and non-causative or consequential. VSD is the most common congenital heart defect in children [ 15 , 27 , 41 , 43 , 44 ]. These often resolve and close spontaneously when the baby is born due to the reversal of vascular resistance at birth. Studies have suggested that overall cardiac function may not be affected by the presence of an isolated EIF when assessed by conventional echocardiography and Tissue Doppler (TD) imaging [ 45 ]. Therefore, in isolation, an EIF may not warrant future follow-up. Previous studies have found an association between the presence of an EIF and the incidence of mitral/tricuspid regurgitation. However, it has been suggested that care needs to be taken when assessing if this is true colour flow generated by atrioventricular valvular regurgitation jets or in fact colour Doppler twinkling artefact (which causes a rapidly changing combination of red and blue complexes behind the EIF which may mimic flow) [ 46 ]. Transient and mild valvular regurgitation can also be seen in fetuses with no cardiovascular anomaly and can be transient and without pathological significance [ 47 ]. Previous research has confirmed rough surfaces, such as that created by microcalcifications or mineralisation in the papillary muscle (which is what EIF is suggested to be) [ 48 , 49 ] is seen to reflect the ultrasound incidence beam and increase pulse duration of received radiofrequency. This may be misinterpreted as movement with the atrioventricular valve when visualised on a foetal echocardiogram [ 46 ]. Finally, the work by Hurt et al. [ 31 ] showed that when the EIF’s were taken to a quality assessment panel, 30% were not confirmed as EIF and were removed from the research analysis. Therefore, the identification of EIF has poor inter-rater reliability.

That there is a link between EIF and cardiac abnormality is supported by Taksande et al. [ 50 ] who recently published a systematic review and meta-analysis and found a prevalence of 4.8% among studies published between 1987–2021. This is comparable to our finding which included 7 of the same studies (but not a meta-analysis) from 2013–2023. The Taksande [ 50 ] analysis did not look at left vs right EIF and did not compare with those without EIF. Our findings suggest, when compared to those without EIF in the same study, only a right sided EIF carries significantly higher risk of cardiac abnormality. A follow-up study by Hurt et al. [ 51 ] published 2023, which followed up the infants with EIF and without EIF for 10 years found no evidence of association of EIF with cardiac admissions or diagnosis of cardiac abnormalities but did find an increased risk of respiratory admissions (Hazard ratio 1.27 (95% CI: 1.04–1.54)). The Hurt study did not look at left vs right EIF but the association with respiratory conditions may support the hypothesis that right sided EIF carries morbidity risk more than left sided EIF.

Strengths and limitations

This work was able to examine outcomes from 15,600 EIFs and reported that EIF at 20 weeks is not significant as a screening tool in pregnancy for infant outcomes at birth. The review covered nine different countries so provides assessment of outcomes for infants of different ethnicities and thus is generalisable. However, the finding that EIF on the right side could carry a 7% risk of cardiac abnormality was based on only two studies and a total of 76 EIFs on the right side. This represents a small sample size which displays high variability in terms of the likelihood of cardiac abnormality (2.9% to 16.9%). An additional study [ 52 ], which was excluded as it was considered that the years of recruitment overlapped with Chiu, 2019 [ 39 ] and so some pregnancies may be replicated in both papers, found a significantly higher prevalence of congenital heart defect in the right ventricle (14.8%, n = 4 cases) compared to left (2.8%, n = 18 cases) (p = 0.0146). In this paper the cases of congenital heart defect were confirmed by postnatal echocardiography and 16.7% (4/24) chose termination of pregnancy upon detection of structural defect. Absence of prospective and contemporary data in the Western world owing to diminished attention to benign EIF may have caused an unintended bias towards ethnic disparity in the current analysis.

This review was not able to examine the risks of persistent right EIFs, which are likely to affect fewer infants but have a higher likelihood of cardiac abnormality. In addition, the variation in studies from different countries means that combining study outcomes to a single score may be prone to error, in terms of concealing the variation which may exist between different ethnic groups.

The studies included in this review used different health care systems and therefore may not be comparable in their definition and identification of adverse infant outcomes. Combining the findings from different studies may also create errors and biases as there is no harmonisation in their definitions of the outcomes. The studies undertaking prospective analysis were prone to missing data and skewed data collection e.g., only those families who returned for assessment were included. Therefore, the prospective studies were rated as weaker and prone to bias compared to the retrospective studies.

The screening process and review was conducted by two independent reviewers performing the extraction in parallel and then comparing decisions to reduce bias. The review benefited from the use of specialist software Covidence to undertake the review [ 25 ]. It allows screening to be more efficient and easily tracked. The date restriction of the last 10 years was justified due to improvements in ultrasound technology in recent years. However, this exclusion criteria may have meant that important previous research was missed.

Recommendations

Persistent EIF in the right side should be investigated using an echocardiogram. There are limited cases and this could help predict cardiovascular abnormality as there is a higher prevalence in this group. However, there is no justification to follow up EIFs on the left and especially those in isolation with no other markers detected. Any recommendation of follow-up would be based on other risk factors such as multiple other soft markers or family history, rather than the presence of an EIF.

This review did not examine the long-term follow-up of infants with EIF and it is possible that persistent EIF could be associated with adult conditions such as VSD or valve regurgitation. Future investigation into failure to thrive, a possible audible murmur, or symptoms such as breathlessness in an infant, may identify longer term adverse outcomes associated with EIF.

Conclusions

In conclusion, we examined the outcomes from 19 studies and present that left sided EIFs are not predictive of poor foetal outcomes, and studies reviewed here suggested these are often transient and resolve with time. Persistent EIF on the right side, which is a rare event in itself, would warrant follow-up. This information is beneficial for pregnant women, families, and clinicians to facilitate the development of appropriate clinical guidelines and care pathways during pregnancy and after birth, including the appropriate use of medical interventions and treatment.

Supporting information

S1 table. extracted variables, definitions and how they were recorded..

https://doi.org/10.1371/journal.pone.0298365.s001

S2 Table. Specific findings from included studies which examine cardiac outcomes.

https://doi.org/10.1371/journal.pone.0298365.s002

https://doi.org/10.1371/journal.pone.0298365.s003

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• Volume 33, Issue 5
• Equitable and accessible informed healthcare consent process for people with intellectual disability: a systematic literature review
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• http://orcid.org/0000-0002-8498-7329 Manjekah Dunn 1 , 2 ,
• Iva Strnadová 3 , 4 , 5 ,
• Jackie Leach Scully 4 ,
• Jennifer Hansen 3 ,
• Julie Loblinzk 3 , 5 ,
• Skie Sarfaraz 5 ,
• Chloe Molnar 1 ,
• Elizabeth Emma Palmer 1 , 2
• 1 Faculty of Medicine & Health , University of New South Wales , Sydney , New South Wales , Australia
• 2 The Sydney Children's Hospitals Network , Sydney , New South Wales , Australia
• 3 School of Education , University of New South Wales , Sydney , New South Wales , Australia
• 4 Disability Innovation Institute , University of New South Wales , Sydney , New South Wales , Australia
• 5 Self Advocacy Sydney , Sydney , New South Wales , Australia
• Correspondence to Dr Manjekah Dunn, Paediatrics & Child Health, University of New South Wales Medicine & Health, Sydney, New South Wales, Australia; manjekah.dunn{at}unsw.edu.au

Objective To identify factors acting as barriers or enablers to the process of healthcare consent for people with intellectual disability and to understand how to make this process equitable and accessible.

Data sources Databases: Embase, MEDLINE, PsychINFO, PubMed, SCOPUS, Web of Science and CINAHL. Additional articles were obtained from an ancestral search and hand-searching three journals.

Eligibility criteria Peer-reviewed original research about the consent process for healthcare interventions, published after 1990, involving adult participants with intellectual disability.

Synthesis of results Inductive thematic analysis was used to identify factors affecting informed consent. The findings were reviewed by co-researchers with intellectual disability to ensure they reflected lived experiences, and an easy read summary was created.

Results Twenty-three studies were included (1999 to 2020), with a mix of qualitative (n=14), quantitative (n=6) and mixed-methods (n=3) studies. Participant numbers ranged from 9 to 604 people (median 21) and included people with intellectual disability, health professionals, carers and support people, and others working with people with intellectual disability. Six themes were identified: (1) health professionals’ attitudes and lack of education, (2) inadequate accessible health information, (3) involvement of support people, (4) systemic constraints, (5) person-centred informed consent and (6) effective communication between health professionals and patients. Themes were barriers (themes 1, 2 and 4), enablers (themes 5 and 6) or both (theme 3).

Conclusions Multiple reasons contribute to poor consent practices for people with intellectual disability in current health systems. Recommendations include addressing health professionals’ attitudes and lack of education in informed consent with clinician training, the co-production of accessible information resources and further inclusive research into informed consent for people with intellectual disability.

PROSPERO registration CRD42021290548.

• Decision making
• Healthcare quality improvement
• Patient-centred care
• Quality improvement
• Standards of care

Data availability statement

Data are available upon reasonable request. Additional data and materials such as data collection forms, data extraction and analysis templates and QualSyst assessment data can be obtained by contacting the corresponding author.

This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/ .

https://doi.org/10.1136/bmjqs-2023-016113

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What is already known on this topic

People with intellectual disability are frequently excluded from decision-making processes and not provided equal opportunity for informed consent, despite protections outlined in the United Nations Convention on the Rights of Persons with Disabilities.

People with intellectual disability have the capacity and desire to make informed medical decisions, which can improve their well-being, health satisfaction and health outcomes.

What this review study adds

Health professionals lack adequate training in valid informed consent and making reasonable adjustments for people with intellectual disability, and continue to perpetuate assumptions of incapacity.

Health information provided to people with intellectual disability is often inaccessible and insufficient for them to make informed decisions about healthcare.

The role of support people, systemic constraints, a person-centred approach and ineffective healthcare communication also affect informed consent.

How this review might affect research, practice or policy

Health professionals need additional training on how to provide a valid informed consent process for people with intellectual disability, specifically in using accessible health information, making reasonable adjustments (e.g., longer/multiple appointments, options of a support person attending or not, using plain English), involving the individual in discussions, and communicating effectively with them.

Inclusive research is needed to hear the voices and opinions of people with intellectual disability about healthcare decision-making and about informed consent practices in specific healthcare settings.

Introduction

Approximately 1% of the world’s population have intellectual disability. 1 Intellectual disability is medically defined as a group of neurodevelopmental conditions beginning in childhood, with below average cognitive functioning and adaptive behaviour, including limitations in conceptual, social and practical skills. 2 People with intellectual disability prefer an alternative strength-based definition, reflected in the comment by Robert Strike OAM (Order of Australia Medal): ‘We can learn if the way of teaching matches how the person learns’, 3 reinforcing the importance of providing information tailored to the needs of a person with intellectual disability. A diagnosis of intellectual disability is associated with significant disparities in health outcomes. 4–7 Person-centred decision-making and better communication have been shown to improve patient satisfaction, 8 9 the physician–patient relationship 10 and overall health outcomes 11 for the wider population. Ensuring people with intellectual disability experience informed decision-making and accessible healthcare can help address the ongoing health disparities and facilitate equal access to healthcare.

Bodily autonomy is an individual’s power and agency to make decisions about their own body. 12 Informed consent for healthcare enables a person to practice bodily autonomy and is protected, for example, by the National Safety and Quality Health Service Standards (Australia), 13 Mental Capacity Act (UK) 14 and the Joint Commission Standards (USA). 15 In this article, we define informed consent according to three requirements: (1) the person is provided with information they understand, (2) the decision is free of coercion and (3) the person must have capacity. 16 For informed consent to be valid, this process must be suited to the individual’s needs so that they can understand and communicate effectively. Capacity is the ability to give informed consent for a medical intervention, 17 18 and the Mental Capacity Act outlines that ‘a person must be assumed to have capacity unless it is established that he lacks capacity’ and that incapacity can only be established if ‘all practicable steps’ to support capacity have been attempted without success. 14 These assumptions of capacity are also decision-specific, meaning an individual’s ability to consent can change depending on the situation, the choice itself and other factors. 17

Systemic issues with healthcare delivery systems have resulted in access barriers for people with intellectual disability, 19 despite the disability discrimination legislation in many countries who are signatories to the United Nations (UN) Convention on the Rights of Persons with Disabilities. 20 Patients with intellectual disability are not provided the reasonable adjustments that would enable them to give informed consent for medical procedures or interventions, 21 22 despite evidence that many people with intellectual disability have both the capacity and the desire to make their own healthcare decisions. 21 23

To support people with intellectual disability to make independent health decisions, an equitable and accessible informed consent process is needed. 24 However, current health systems have consistently failed to provide this. 21 25 To address this gap, we must first understand the factors that contribute to inequitable and inaccessible consent. To the best of our knowledge, the only current review of informed consent for people with intellectual disability is an integrative review by Goldsmith et al . 26 Many of the included articles focused on assessment of capacity 27–29 and research consent. 30–32 The review’s conclusion supported the functional approach to assess capacity, with minimal focus on how the informed consent processes can be improved. More recently, there has been a move towards ensuring that the consent process is accessible for all individuals, including elderly patients 33 and people with aphasia. 34 However, there remains a paucity of literature about the informed consent process for people with intellectual disability, with no systematic reviews summarising the factors influencing the healthcare consent process for people with intellectual disability.

To identify barriers to and enablers of the informed healthcare consent process for people with intellectual disability, and to understand how this can be made equitable and accessible.

A systematic literature review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis Protocols (PRISMA-P) systematic literature review protocol. 35 The PRISMA 2020 checklist 36 and ENhancing Transparency in REporting the synthesis of Qualitative research (ENTREQ) reporting guidelines were also followed. 37 The full study protocol is included in online supplemental appendix 1 .

Supplemental material

No patients or members of the public were involved in this research for this manuscript.

Search strategy

A search strategy was developed to identify articles about intellectual disability, consent and healthcare interventions, described in online supplemental appendix 2 . Multiple databases were searched for articles published between January 1990 to January 2022 (Embase, MEDLINE, PsychINFO, PubMed, SCOPUS, Web of Science and CINAHL). These databases include healthcare and psychology databases that best capture relevant literature on this topic, including medical, nursing, social sciences and bioethical literature. The search was limited to studies published from 1990 as understandings of consent have changed since then. 38 39 This yielded 4853 unique papers which were imported into Covidence, a specialised programme for conducting systematic reviews. 40

Study selection

Citation screening by abstract and titles was completed by two independent researchers (MD and EEP). Included articles had to:

Examine the informed consent process for a healthcare intervention for people with intellectual disability.

Have collected more than 50% of its data from relevant stakeholders, including adults with intellectual disability, families or carers of a person with intellectual disability, and professionals who engage with people with intellectual disability.

Report empirical data from primary research methodology.

Be published in a peer-reviewed journal after January 1990.

Be available in English.

Full text screening was completed by two independent researchers (MD and EEP). Articles were excluded if consent was only briefly discussed or if it focused on consent for research, capacity assessment, or participant knowledge or comprehension. Any conflicts were resolved through discussion with an independent third researcher (IS).

Additional studies were identified through an ancestral search and by hand-searching three major journals relevant to intellectual disability research. Journals were selected if they had published more than one included article for this review or in previous literature reviews conducted by the research team.

Quality assessment

Two independent researchers (MD and IS) assessed study quality with the QualSyst tool, 41 which can assess both qualitative and quantitative research papers. After evaluating the distribution of scores, a threshold value of 55% was used, as suggested by QualSyst 41 to exclude poor-quality studies but capture enough studies overall. Any conflicts between the quality assessment scores were resolved by a third researcher (EEP). For mixed-method studies, both qualitative and quantitative quality scores were calculated, and the higher value used.

Data collection

Two independent researchers (MD and JH) reviewed each study and extracted relevant details, including study size, participant demographics, year, country of publication, study design, data analysis and major outcomes reported. Researchers used standardised data collection forms designed, with input from senior researchers with expertise in qualitative research (IS and EEP), to extract data relevant to the review’s research aims. The form was piloted on one study, and a second iteration made based on feedback. These forms captured data on study design, methods, participants, any factors affecting the process of informed consent and study limitations. Data included descriptions and paragraphs outlining key findings, the healthcare context, verbatim participant quotes and any quantitative analyses or statistics. Missing or unclear data were noted.

Data analysis

A pilot literature search showed significant heterogeneity in methodology of studies, limiting the applicability of traditional quantitative analysis (ie, meta-analysis). Instead, inductive thematic analysis was chosen as an alternative methodology 42 43 that has been used in recent systematic reviews examining barriers and enablers of other health processes. 44 45 The six-phase approach described by Braun and Clarke was used. 46 47 A researcher (MD) independently coded the extracted data of each study line-by-line, with subsequent data grouped into pre-existing codes or new concepts when necessary. Codes were reviewed iteratively and grouped into categories, subthemes and themes framed around the research question. Another independent researcher (JH) collated and analysed the data on study demographics, methods and limitations. The themes were reviewed by two senior researchers (EEP and IS).

Qualitative methods of effect size calculations have been described in the literature, 48 49 which was captured in this review by the number of studies that identified each subtheme, with an assigned frequency rating to compare their relative significance. Subthemes were given a frequency rating of A, B, C or D if they were identified by >10, 7–9, 4–6 or <3 articles, respectively. The overall significance of each theme was estimated by the number of studies that mentioned it and the GRADE framework, a stepwise approach to quality assessment using a four-tier rating system. Each study was evaluated for risk of bias, inconsistency, indirectness, imprecision and publication bias. 50 51 Study sensitivity was assessed by counting the number of distinct subthemes included. 52 The quality of findings was designated high, moderate or low depending on the frequency ratings, the QualSyst score and the GRADE scores of studies supporting the finding. Finally, the relative contributions of each study were evaluated by the number of subthemes described, guided by previously reported methods for qualitative reviews. 52

Co-research

The findings were reviewed by two co-researchers with intellectual disability (JL and SS), with over 30 years combined experience as members and employees of a self-advocacy organisation. Guidance on the findings and an easy read summary was produced in line with best-practice inclusive research 53 54 over multiple discussions. Input from two health professional researchers (MD and EEP) provided data triangulation and sense-checking of findings.

Twenty-three articles were identified ( figure 1 ): 14 qualitative, 6 quantitative and 3 mixed-methods. Two papers included the same population of study participants: McCarthy 55 and McCarthy, 56 but had different research questions. Fovargue et al 57 was excluded due to a quality score of 35%. Common quality limitations were a lack of verification procedures to establish credibility and limited researcher reflexivity. No studies were excluded due to language requirements (as all were in English) or age restrictions (all studies had majority adult participants).

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PRISMA 2020 flowchart for the systematic review. 36

Studies were published from 1999 to 2020 and involved participant populations from the UK (n=18), USA (n=3), Sweden (n=1) and Ireland (n=1). Participant numbers ranged from 9 to 604 (median 21), and participants included people with intellectual disability (n=817), health professionals (n=272), carers and support people (n=48), and other professionals that work with people with intellectual disability (n=137, community service agency directors, social workers, administrative staff and care home staff). Ages of participants ranged from 8 to 84 years, though only Aman et al 58 included participants <18 years of age. This study was included as the article states very few children were included. Studies examined consent in different contexts, including contraception and sexual health (6/23 articles), 58–60 medications (5/23 articles), 58–62 emergency healthcare, 63 cervical screening, 64 community referrals, 58–61 65 mental health, 66 hydrotherapy, 64 blood collection 67 and broad decision-making consent without a specific context. 65 68–71 A detailed breakdown of each study is included in online supplemental appendix 3 .

Six major themes were identified from the studies, summarised in figure 2 . An overview of included studies showing study sensitivity, effect size, QualSyst and GRADE scores is given in online supplemental appendix 4 . Studies with higher QualSyst and GRADE scores contributed more to this review’s findings and tended to include more subthemes; specifically, Rogers et al , 66 Sowney and Barr, 63 Höglund and Larsson, 72 and McCarthy 55 and McCarthy. 56 Figure 3 gives the easy read version of theme 1, with the full easy read summary in online supplemental appendix 5 .

Summary of the identified six themes and subthemes.

Theme 1 of the easy read summary.

Theme 1—Health professionals’ attitudes and lack of education about informed consent

Health professionals’ attitudes and practices were frequently (18/21) identified as factors affecting the informed consent process, with substantial evidence supporting this theme. Studies noted the lack of training for health professionals in supporting informed consent for people with intellectual disability, their desire for further education, and stereotypes and discrimination perpetuated by health professionals.

Lack of health professional education on informed consent and disability discrimination legislation

Multiple studies reported inconsistent informed consent practices, for various reasons: some reported that health professionals ‘forgot’ to or ‘did not realise consent was necessary’, 63 73 but inconsistent consent practices were also attributed to healthcare providers’ unfamiliarity with consent guidelines and poor education on this topic. Carlson et al 73 reported that only 44% of general practitioners (GPs) were aware of consent guidelines, and there was the misconception that consent was unnecessary for people with intellectual disability. Similarly, studies of psychologists 66 and nurses 63 found that many were unfamiliar with their obligations to obtain consent, despite the existence of anti-discrimination legislation. People with intellectual disability describe feeling discriminated against by health professionals, reflected in comments such as ‘I can tell, my doctor just thinks I’m stupid – I'm nothing to him’. 74 Poor consent practices by health professionals were observed in Goldsmith et al , 67 while health professionals surveyed by McCarthy 56 were unaware of their responsibility to provide accessible health information to women with intellectual disability. Improving health professional education and training was suggested by multiple studies as a way to remove this barrier. 63 65–67 69 73

Lack of training on best practices for health professions caring for people with intellectual disability

A lack of training in caring for and communicating with people with intellectual disability was also described by midwives, 72 psychologists, 66 nurses, 63 pharmacists 61 and GPs. 56 72 75 Health professionals lacked knowledge about best practice approaches to providing equitable healthcare consent processes through reasonable adjustments such as accessible health information, 56 60 66 longer appointments times, 60 72 simple English 62 67 and flexible approaches to patient needs. 63 72

Health professionals’ stereotyping and assumptions of incapacity

Underlying stereotypes contributed to some health professionals’ (including nurses, 63 GPs 56 and physiotherapists 64 ) belief that people with intellectual disability lack capacity and therefore, do not require opportunities for informed consent. 56 64 In a survey of professionals referring people with intellectual disability to a disability service, the second most common reason for not obtaining consent was ‘patient unable to understand’. 73

Proxy consent as an inappropriate alternative

People with intellectual disability are rarely the final decision-maker in their medical choices, with many health providers seeking proxy consent from carers, support workers and family members, despite its legal invalidity. In McCarthy’s study (2010), 18/23 women with intellectual disability said the decision to start contraception was made by someone else. Many GPs appeared unaware that proxy consent is invalid in the UK. 56 Similar reports came from people with intellectual disability, 55 56 60 64 69 76 health professionals (nurses, doctors, allied health, psychologists), 56 63 64 66 77 support people 64 77 and non-medical professionals, 65 73 and capacity was rarely documented. 56 62 77

Exclusion of people with intellectual disability from decision-making discussions

Studies described instances where health professionals made decisions for their patients with intellectual disability or coerced patients into a choice. 55 72 74 76 77 In Ledger et al 77 , only 62% of women with intellectual disability were involved in the discussion about contraception, and only 38% made the final decision, and others stated in Wiseman and Ferrie 74 : ‘I was not given the opportunity to explore the different options. I was told what one I should take’. Three papers outlined instances where the choices of people with intellectual disability were ignored despite possessing capacity 65 66 69 and when a procedure continued despite them withdrawing consent. 69

Theme 2—Inadequate accessible health information

Lack of accessible health information.

The lack of accessible health information was the most frequently identified subtheme (16/23 studies). Some studies reported that health professionals provided information to carers instead, 60 avoided providing easy read information due to concerns about ‘offending’ patients 75 or only provided verbal information. 56 67 Informed consent was supported when health professionals recognised the importance of providing medical information 64 and when it was provided in an accessible format. 60 Alternative approaches to health information were explored, including virtual reality 68 and in-person education sessions, 59 with varying results. Overall, the need to provide information in different formats tailored to an individual’s communication needs, rather than a ‘one size fits all’ approach, was emphasised by both people with intellectual disability 60 and health professionals. 66

Insufficient information provided

Studies described situations where insufficient information was provided to people with intellectual disability to make informed decisions. For example, some people felt the information from their GP was often too basic to be helpful (Fish et al 60 ) and wanted additional information on consent forms (Rose et al 78 ).

Theme 3—The involvement of support people

Support people (including carers, family members and group home staff) were identified in 11 articles as both enablers of and barriers to informed consent. The antagonistic nature of these findings and lower frequency of subthemes are reflected in the lower quality assessments of evidence.

Support people facilitated communication with health professionals

Some studies reported carers bridging communication barriers with health to support informed consent. 63 64 McCarthy 56 found 21/23 of women with intellectual disability preferred to see doctors with a support person due to perceived benefits: ‘Sometimes I don’t understand it, so they have to explain it to my carer, so they can explain it to me easier’. Most GPs in this study (93%) also agreed that support people aided communication.

Support people helped people with intellectual disability make decisions

By advocating for people with intellectual disability, carers encouraged decision-making, 64 74 provided health information, 74 77 emotional support 76 and assisted with reading or remembering health information. 55 58 76 Some people with intellectual disability explicitly appreciated their support person’s involvement, 60 such as in McCarthy’s 55 study where 18/23 participants felt supported and safer when a support person was involved.

Support people impeded individual autonomy

The study by Wiseman and Ferrie 74 found that while younger participants with intellectual disability felt family members empowered their decision-making, older women felt family members impaired their ability to give informed consent. This was reflected in interviews with carers who questioned the capacity of the person with intellectual disability they supported and stated they would guide them to pick the ‘best choice’ or even over-ride their choices. 64 Studies of psychologists and community service directors described instances where the decision of family or carers was prioritised over the wishes of the person with intellectual disability. 65 66 Some women with intellectual disability in McCarthy’s studies (2010, 2009) 55 56 appeared to have been coerced into using contraception by parental pressures or fear of losing group home support.

Theme 4—Systemic constraints within healthcare systems

Time restraints affect informed consent and accessible healthcare.

Resource limitations create time constraints that impair the consent process and have been identified as a barrier by psychologists, 66 GPs, 56 hospital nurses 63 and community disability workers. 73 Rogers et al 66 highlighted that a personalised approach that could improve informed decision-making is restricted by inflexible medical models. Only two studies described flexible patient-centred approaches to consent. 60 72 A survey of primary care practices in 2007 reported that most did not modify their cervical screening information for patients with intellectual disability because it was not practical. 75

Inflexible models of consent

Both people with intellectual disability 76 and health professionals 66 recognised that consent is traditionally obtained through one-off interactions prior to an intervention. Yet, for people with intellectual disability, consent should ideally be an ongoing process that begins before an appointment and continues between subsequent ones. Other studies have tended to describe one-off interactions where decision-making was not revisited at subsequent appointments. 56 60 72 76

Lack of systemic supports

In one survey, self-advocates highlighted a lack of information on medication for people with intellectual disability and suggested a telephone helpline and a centralised source of information to support consent. 60 Health professionals also want greater systemic support, such as a health professional specialised in intellectual disability care to support other staff, 72 or a pharmacist specifically to help patients with intellectual disability. 61 Studies highlighted a lack of guidelines about healthcare needs of people with intellectual disabilities such as contraceptive counselling 72 or primary care. 75

Theme 5—Person-centred informed consent

Ten studies identified factors related to a person-centred approach to informed consent, grouped below into three subthemes. Health professionals should tailor their practice when obtaining informed consent from people with intellectual disability by considering how these subthemes relate to the individual. Each subtheme was described five times in the literature with a relative frequency rating of ‘C’, contributing to overall lower quality scores.

Previous experience with decision-making

Arscott et al 71 found that the ability of people with intellectual disability to consent changed with their verbal and memory skills and in different clinical vignettes, supporting the view of ‘functional’ capacity specific to the context of the medical decision. Although previous experiences with decision-making did not influence informed consent in this paper, other studies suggest that people with intellectual disability accustomed to independent decision-making were more able to make informed medical decisions, 66 70 and those who live independently were more likely to make independent healthcare decisions. 56 Health professionals should be aware that their patients with intellectual disability will have variable experience with decision-making and provide individualised support to meet their needs.

Variable awareness about healthcare rights

Consent processes should be tailored to the health literacy of patients, including emphasising available choices and the option to refuse treatment. In some studies, medical decisions were not presented to people with intellectual disability as a choice, 64 and people with intellectual disability were not informed of their legal right to accessible health information. 56

Power differences and acquiescence

Acquiescence by people with intellectual disability due to common and repeated experiences of trauma—that is, their tendency to agree with suggestions made by carers and health professionals, often to avoid upsetting others—was identified as an ongoing barrier. In McCarthy’s (2009) interviews with women with intellectual disability, some participants implicitly rejected the idea that they might make their own healthcare decisions: ‘They’re the carers, they have responsibility for me’. Others appeared to have made decisions to appease their carers: ‘I have the jab (contraceptive injection) so I can’t be blamed for getting pregnant’. 55 Two studies highlighted that health professionals need to be mindful of power imbalances when discussing consent with people with intellectual disability to ensure the choices are truly autonomous. 61 66

Theme 6—Effective communication between health professionals and patients

Implementation of reasonable adjustments for verbal and written information.

Simple language was always preferred by people with intellectual disability. 60 67 Other communication aids used in decision-making included repetition, short sentences, models, pictures and easy read brochures. 72 Another reasonable adjustment is providing the opportunity to ask questions, which women with intellectual disability in McCarthy’s (2009) study reported did not occur. 55

Tailored communication methods including non-verbal communication

Midwives noted that continuity of care allows them to develop rapport and understand the communication preferences of people with intellectual disability. 72 This is not always possible; for emergency nurses, the lack of background information about patients with intellectual disability made it challenging to understand their communication preferences. 63 The use of non-verbal communication, such as body language, was noted as underutilised 62 66 and people with intellectual disability supported the use of hearing loops, braille and sign language. 60

To the best of our knowledge, this is the first systematic review investigating the barriers and enablers of the informed consent process for healthcare procedures for people with intellectual disability. The integrative review by Goldsmith et al 26 examined capacity assessment and shares only three articles with this systematic review. 69 71 73 Since the 2000s, there has been a paradigm shift in which capacity is no longer considered a fixed ability that only some individuals possess 38 39 but instead as ‘functional’: a flexible ability that changes over time and in different contexts, 79 reflected in Goldsmith’s review. An individual’s capacity can be supported through various measures, including how information is communicated and how the decision-making process is approached. 18 80 By recognising the barriers and enablers identified in this review, physicians can help ensure the consent process for their patients with intellectual disability is both valid and truly informed. This review has highlighted the problems of inaccessible health information, insufficient clinical education on how to make reasonable adjustments and lack of person-centred trauma-informed care.

Recommendations

Health professionals require training in the informed consent process for people with intellectual disability, particularly in effective and respectful communication, reasonable adjustments and trauma-informed care. Reasonable adjustments include offering longer or multiple appointments, using accessible resources (such as easy read information or shared decision-making tools) and allowing patient choices (such as to record a consultation or involve a support person). Co-researchers reported that many people with intellectual disability prefer to go without a support person because they find it difficult to challenge their decisions and feel ignored if the health professional only talks to the support person. People with intellectual disability also feel they cannot seek second opinions before making medical decisions or feel pressured to provide consent, raising the possibility of coercion. These experiences contribute to healthcare trauma. Co-researchers raised the importance of building rapport with the person with intellectual disability and of making reasonable adjustments, such as actively advocating for the person’s autonomy, clearly stating all options including the choice to refuse treatment, providing opportunities to contribute to discussions and multiple appointments to ask questions and understand information. They felt that without these efforts to support consent, health professionals can reinforce traumatic healthcare experiences for people with intellectual disability. Co-researchers noted instances where choices were made by doctors without discussion and where they were only given a choice after requesting one and expressed concern that these barriers are greater for those with higher support needs.

Co-researchers showed how these experiences contributed to mistrust of health professionals and poorer health outcomes. In one situation, a co-researcher was not informed of a medication’s withdrawal effects, resulting in significant side-effects when it was ceased. Many people with intellectual disability describe a poor relationship with their health professionals, finding it difficult to trust health information provided due to previous traumatic experiences of disrespect, coercion, lack of choice and inadequate support. Many feel they cannot speak up due to the power imbalance and fear of retaliation. Poor consent practices and lack of reasonable adjustments directly harm therapeutic alliances by reducing trust, contribute to healthcare trauma and lead to poorer health outcomes for people with intellectual disability.

Additional education and training for health professionals is urgently needed in the areas of informed consent, reasonable adjustments and effective communication with people with intellectual disability. The experiences of health professionals within the research team confirmed that there is limited training in providing high-quality healthcare for people with intellectual disability, including reasonable adjustments and accessible health information. Co-researchers also suggested that education should be provided to carers and support people to help them better advocate for people with intellectual disability.

Health information should be provided in a multimodal format, including written easy read information. Many countries have regulation protecting the right to accessible health information and communication support to make an informed choice, such as UK’s Accessible Information Standard, 81 and Australia’s Charter of Health Care Rights, 24 yet these are rarely observed. Steps to facilitate this include routinely asking patients about information requirements, system alerts for an individual’s needs or routinely providing reasonable adjustments. 82 Co-researchers agreed that there is a lack of accessible health information, particularly about medications, and that diagrams and illustrations are underutilised. There is a critical need for more inclusive and accessible resources to help health professionals support informed consent in a safe and high-quality health system. These resources should be created through methods of inclusive research, such as co-production, actively involving people with intellectual disability in the planning, creation, and feedback process. 53

Strengths and limitations

This systematic review involved two co-researchers with intellectual disability in sense-checking findings and co-creating the easy read summary. Two co-authors who are health professionals provided additional sense-checking of findings from a different stakeholder perspective. In future research, this could be extended by involving people with intellectual disability in the design and planning of the study as per recommendations for best-practice inclusive research. 53 83

The current literature is limited by low use of inclusive research practices in research involving people with intellectual disability, increasing vulnerability to external biases (eg, inaccessible questionnaires, involvement of carers in data collection, overcompliance or acquiescence and absence of researcher reflexivity). Advisory groups or co-research with people with intellectual disability were only used in five studies. 58 60 68 74 76 Other limitations include unclear selection criteria, low sample sizes, missing data, using gatekeepers in patient selection and predominance of UK-based studies—increasing the risk of bias and reducing transferability. Nine studies (out of 15 involving people with intellectual disability) explicitly excluded those with severe or profound intellectual disability, reflecting a selection bias; only one study specifically focused on people with intellectual disability with higher support needs. Studies were limited to a few healthcare contexts, with a focus on consent about sexual health, contraception and medications.

The heterogeneity and qualitative nature of studies made it challenging to apply traditional meta-analysis. However, to promote consistency in qualitative research, the PRISMA and ENTREQ guidelines were followed. 36 37 Although no meta-analyses occurred, the duplication of study populations in McCarthy 2009 and 2010 likely contributed to increased significance of findings reported in both studies. Most included studies (13/23) were published over 10 years ago, reducing the current relevance of this review’s findings. Nonetheless, the major findings reflect underlying systemic issues within the health system, which are unlikely to have been resolved since the articles were published, as the just-released final report of the Australian Royal Commission into Violence, Abuse, Neglect and Exploitation of People with Disability highlights. 84 There is an urgent need for more inclusive studies to explore the recommendations and preferences of people with intellectual disability about healthcare choices.

Informed consent processes for people with intellectual disability should include accessible information and reasonable adjustments, be tailored to individuals’ needs and comply with consent and disability legislation. Resources, guidelines and healthcare education are needed and should cover how to involve carers and support people, address systemic healthcare problems, promote a person-centred approach and ensure effective communication. These resources and future research must use principles of inclusive co-production—involving people with intellectual disability at all stages. Additionally, research is needed on people with higher support needs and in specific contexts where informed consent is vital but under-researched, such as cancer screening, palliative care, prenatal and newborn screening, surgical procedures, genetic medicine and advanced therapeutics such as gene-based therapies.

Ethics statements

Patient consent for publication.

Not applicable.

Ethics approval

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Supplementary materials

Supplementary data.

This web only file has been produced by the BMJ Publishing Group from an electronic file supplied by the author(s) and has not been edited for content.

• Data supplement 1
• Data supplement 2
• Data supplement 3
• Data supplement 4
• Data supplement 5

Contributors MD, EEP and IS conceived the idea for the systematic review. MD drafted the search strategy which was refined by EEP and IS. MD and EEP completed article screening. MD and IS completed quality assessments of included articles. MD and JH completed data extraction. MD drafted the original manuscript. JL and SS were co-researchers who sense-checked findings and were consulted to formulate dissemination plans. JL and SS co-produced the easy read summary with MD, CM, JH, EEP and IS. MD, JLS, EEP and IS reviewed manuscript wording. All authors critically reviewed the manuscript and approved it for publication. The corresponding author attests that all listed authors meet authorship criteria and that no others meeting the criteria have been omitted. MD is the guarantor responsible for the overall content of this manuscript.

Funding This systematic literature review was funded by the National Health & Medical Research Council (NHMRC), Targeted Call for Research (TCR) into Improving health of people with intellectual disability. Research grant title "GeneEQUAL: equitable and accessible genomic healthcare for people with intellectual disability". NHMRC application ID: 2022/GNT2015753.

Competing interests None declared.

Provenance and peer review Not commissioned; externally peer reviewed.

Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.

Linked Articles

• Editorial It is up to healthcare professionals to talk to us in a way that we can understand: informed consent processes in people with an intellectual disability Jonathon Ding Richard Keagan-Bull Irene Tuffrey-Wijne BMJ Quality & Safety 2024; 33 277-279 Published Online First: 30 Jan 2024. doi: 10.1136/bmjqs-2023-016830

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• Volume 55, Number 2, April 2024

ariel: A Review of International English Literature , is focused on the critical and scholarly study of global literatures in English. The journal publishes articles in postcolonial studies exploring issues of colonial power and resistance as well as innovative scholarship on globalization, new forms and sites of exploitation and colonization in an age of transnational capitalism, displacement and diaspora studies, global ecocriticism, cultural and cross-cultural translation, and related areas. Founded in 1970 as one of the first journals in Commonwealth studies, ariel has remained at the forefront of postcolonial and world literature criticism, with readers and subscribers in more than 50 countries around the globe.

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• DOI: https://doi.org/10.1353/ari.2024.a925426

• Saprophytic: Decomposition and Tropical Environmental Time in Caribbean Literature
• Suzanne F. Boswell
• DOI: https://doi.org/10.1353/ari.2024.a925427
• "Odd but recognizable": Indigenous Epistemologies and Indo-Creole Belonging in Cyril Dabydeen's Dark Swirl
• Najnin Islam
• DOI: https://doi.org/10.1353/ari.2024.a925428
• Power, Painting, and Poetry: Mixed-Race Ekphrasis in Natasha Trethewey's Thrall
• Juliann Knaus
• DOI: https://doi.org/10.1353/ari.2024.a925429
• Dancing Bodies in Zadie Smith's Swing Time
• Karen Ya-Chu Yang
• DOI: https://doi.org/10.1353/ari.2024.a925430
• Camptown Dwelling: Environment and Survival in Memories of My Ghost Brother
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• DOI: https://doi.org/10.1353/ari.2024.a925431
• Literary Rebels: A History of Creative Writers in Anglo-American Universities by Lise Jaillant (review)
• Naomi Booth
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• DOI: https://doi.org/10.1353/ari.2024.a925432
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• David Callahan
• pp. 138-141
• DOI: https://doi.org/10.1353/ari.2024.a925433
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• Marzia Milazzo
• pp. 141-145
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• Published: 26 April 2024

Risk factors for low back pain in the Chinese population: a systematic review and meta-analysis

• Qiang Li 1 ,
• Leyun Peng 1 ,
• Yiding Wang 2 ,
• Yonghui Yang 1 , 3 &
• Zongbao Wang 1  

BMC Public Health volume  24 , Article number:  1181 ( 2024 ) Cite this article

Metrics details

In China, the world’s largest developing country, low back pain (LBP) is a common public health issue affecting workability. This meta-analysis aimed to systematically assess the risk factors of LBP in the Chinese population.

Four English language and four Chinese databases were searched, and cross-sectional studies on the risk factors for LBP in Chinese populations were identified and collected. The search timeframe covered the period from the establishment of the database to November 2023. Two researchers independently reviewed the literature, extracted the data, and evaluated the risk of bias. Begg’s and Egger’s tests were used to evaluate publication bias.

Fifteen cross-sectional studies involving 86,575 people were included. Seven risk factors for LBP were identified. Six risk factors were statistically significant: Cigarette smoking (odds ratio [OR] = 1.55; 95% confidence interval [CI]: 1.15, 2.08, P  = 0.004, I 2  = 72%), body mass index (BMI) ≥ 28 kg/m² (OR = 4.51; 95% CI: 3.36, 6.07, P  < 0.00001, I 2  = 8%), female sex (OR = 1.54; 95% CI: 1.25, 1.90, P  < 0.0001, I 2  = 63%), vibration exposure at work (OR = 1.65; 95% CI: 1.16, 2.34, P  = 0.006, I 2  = 84%), working overtime (OR = 2.57; 95% CI: 1.12, 5.91, P  = 0.03, I 2  = 85%), and lack of exercise (OR = 2.48; 95% CI: 1.62, 3.78, P  < 0.0001, I 2  = 0%). One risk factor that was not statistically significant was standing for long periods (OR = 1.02; 95% CI: 0.82, 1.26, P  = 0.88, I 2  = 73%).

Conclusions

This study found that smoking, a BMI ≥ 28 kg/m², female sex, vibration exposure at work, working overtime, and lack of exercise may be risk factors for LBP in the Chinese population. Because the included studies were cross-sectional and the certainty of the evidence was very low, the results need to be interpreted cautiously. Multicentre, high-quality studies should be conducted in the future. To reduce the prevalence of LBP, the Chinese government and hospitals must develop early screening programs and implement effective preventive and interventional measures.

Trial registration

This study is registered in the PROSPERO database (No. CRD42023447857).

Peer Review reports

Low back pain (LBP) is a common symptom of many known and unknown pathologies or diseases [ 1 ]. Pain is usually located at the lower edge of the ribs, in the lumbosacral region, or accompanied by unilateral and bilateral lower limb nervous system symptoms [ 2 ]. LBP is a health problem that can occur in all age groups. According to literature reports, approximately 90% of people worldwide experience LBP at some stage of their lives [ 3 ]. LBP ranks sixth among all disease burdens in developed and developing countries [ 4 , 5 ]. Hartvigsen et al. reported [ 1 ] that the global economic burden of LBP is likely to increase further.

In China, LBP is also a major public health problem. According to Chen et al. [ 6 ], the annual prevalence of LBP in Chinese adults is 20.88–29.88%. This is closely related to China’s social and economic conditions. China is a large agricultural country with a population of more than 1.4 billion, and many people perform manual labour work. Furthermore, the level of agricultural mechanisation in China is significantly lower than that in developed countries [ 7 ], and the degree of industrial intelligence is also relatively low. As a rapidly emerging developing country, many adults in China work long hours to earn more income for their household expenses in response to escalating costs of living [ 8 ]. During their leisure time, the participation rate of Chinese people in sports activities was only 13.8%, which was significantly lower than that in Western countries [ 9 ]. The vast differences between Chinese and Western cultures and the lack of medical knowledge in the Chinese population may aggravate the occurrence of chronic pain in the Chinese population [ 10 ]. One study found that the prevalence of chronic pain in China was 31.54%, and most patients with chronic pain were in the northern and southern coastal areas [ 10 ]. Among the patients with chronic pain, 24.06% did not visit the hospital, and 36.788% did not receive any treatment [ 10 ]. Compared with developed Western countries, Chinese people have an insufficient understanding of chronic pain; the medical treatment rate of the affected population is low, and the number of patients undergoing standard treatment is also low [ 10 ]. Additionally, there are 1.14 billion smokers worldwide and an estimated 306 million adult smokers in China, the country with the largest number of smokers worldwide [ 11 , 12 ]. China’s economic development, popularisation of medical knowledge, and lifestyle habits show unique characteristics. These factors jointly affect LBP prevalence and risk in the Chinese population.

The risk factors for LBP reported in the literature can be divided into three aspects: (1) lifestyle factors such as obesity, smoking, and lack of exercise; (2) social factors such as working overtime, physical labour, education, and job satisfaction; and (3) psychological factors such as depression and anxiety [ 1 , 13 , 14 ]. If people have an unhealthy lifestyle, choose to eat junk food, smoke, and are unwilling to exercise, there is an increased risk of LBP. In highly competitive metropolitan cities, employees often work overtime and engage in heavy physical labour, resulting in low job satisfaction and the possibility of LBP. However, psychological factors are often overlooked. A cross-sectional study in South Korea found that the severity of depressive symptoms was associated with an increased risk of LBP [ 15 ]. A retrospective study conducted in the United States revealed that a healthy emotional state and a positive lifestyle can aid recovery from LBP [ 16 ]. In addition, regarding certain factors such as prolonged standing and education level, the research findings are inconsistent. Research conducted by Li et al. [ 17 ] and Jia et al. [ 18 ] indicate that prolonged standing may be a protective factor against LBP, whereas research conducted by Peng et al. [ 19 ] and Yue et al. [ 20 ] shows otherwise. Conflicting research is also seen in education. Xu et al. [ 21 ], Liu [ 22 ], and Jia et al. [ 18 ] reported an association between education and LBP, whereas Ye et al. [ 23 ] reported the opposite. The inconsistency in these research results may be related to the significant differences in the industries in which the research participants were located.

Although existing studies have provided valuable knowledge about LBP, few studies on the risk factors of LBP in the Chinese population exist. Investigations and research are limited by the sample size and study population. After reviewing Chinese and English language databases, we could not locate any evidence-based studies on the risk factors for LBP in the Chinese population. This finding suggests a systematic and quantitative approach is required to address this issue. As an evidence-based research method, meta-analysis can comprehensively analyse the results of multiple studies, improve the accuracy of result estimation, and identify and quantify potential risk factors. Therefore, the purpose of this study was to systematically review and integrate existing studies on the risk factors of LBP in the Chinese population through a meta-analysis. The aims were to enhance statistical precision, address inconsistencies among studies, and ensure robust conclusions, thereby providing an evidence-based foundation for formulating effective prevention and intervention strategies.

This evidence-based medical study is registered in The International Prospective Register of Systematic Reviews (PROSPERO) database (No. CRD42023447857). The study was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines [ 24 , 25 ].

Search strategy

PubMed, Web of Science, Embase, Cochrane Library, CNKI, WanFang Date, VIP, and CBM databases were searched to collect cross-sectional studies on the risk factors for LBP in the Chinese population. From the time the databases were created until 1 November 2023, eight databases were searched using MeSH Terms, index terms, and keywords. Chinese search terms: ‘low back pain’ or ‘lower back pain’, ‘risk factors’ or ‘influencing factors’ or ‘related factors’. The English language search strategy is detailed in Additional File 1 .

Inclusion criteria

Research individuals: People with LBP (pain arising from the lower edge of the ribs in the lumbosacral and sacroiliac areas, with or without radiating pain in the lower limbs [ 2 ]) in China.

Exposure factors: Risk factors that may lead to the onset of LBP.

Outcome measure: Clinical diagnosis confirming the presence of LBP.

Study type: Cross-sectional studies.

Studies with original clear odds ratios (ORs) and 95% confidence intervals (95% CIs).

Language: Chinese and English.

Exclusion criteria

Republished studies.

Studies with different research participants and methods.

Studies on individuals with lumbar stenosis or other comorbidities.

Dissertations and conference papers.

Research lacking data or not including analytical factors.

Data extraction and quality assessment

Two researchers (Qiang Li and Yiding Wang) with extensive retrieval experience read the literature and extracted the information. The contents of the records included the first author, publication year, sample size, risk factors, and OR (95% CI). The third researcher (Leyun Peng) made the final decision whenever problems were encountered regarding data extraction; quality was evaluated. Two reviewers evaluated cross-sectional studies using the Agency for Healthcare Research and Quality methods [ 26 ]. With this method [ 27 ], 1–3 points mean low quality, 4–7 points mean medium, and 8–11 points mean high quality. In the Newcastle-Ottawa Scale, 0–4 points mean low quality, 5–6 points mean medium, and 7–9 points mean high quality.

The Grading of Recommendations, Assessment, Development, and Evaluation system [ 28 ] was employed to assess the evidence quality for the risk factors. This is based on factors such as study design, risk of bias, imprecision, inconsistency, indirectness, publication bias, and effect size [ 29 , 30 , 31 , 32 , 33 , 34 ]. The level of evidence was categorised as high, medium, low, or very low.

Statistical analyses

To guarantee the accuracy of the pooled effect estimates, we conducted a meta-analysis based solely on risk factors evaluated in a minimum of four studies. We used Revman 5.3 software for statistical analysis. OR (95% CI) was used as the effect analysis statistic. I² was used to test heterogeneity using P -values. Low, moderate, and high degrees of heterogeneity were indicated by the I 2 statistical values of 25, 50, and 75%, respectively [ 35 ]. When I 2 was > 50%, sensitivity analyses were performed to exclude each study individually to determine the stability of the findings. Funnel plot analysis was performed when at least 10 studies were included. Begg’s and Egger’s tests were used to evaluate the publication bias.

Study selection

We initially searched the database and obtained 1,984 records. In total, 836 duplicate records were deleted using EndNote X9. We then reviewed the titles and abstracts of the literature and excluded 1,051 records. After reading the full texts, 82 studies were excluded. Finally, 15 studies were included for appraisal and analysis. A flow chart of the article screening is shown in Fig.  1 . The studies excluded in the final step are presented in Additional File 2 .

Flow chart of the search process for the studies

Study characteristics and methodologic quality

The basic characteristics and quality assessment results of the included studies are summarised in Table  1 . For details of the quality assessment of the literature, please refer to Additional File 3 . Fifteen papers [ 18 , 19 , 20 , 22 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 ] were published between 2006 and 2022. The sample size ranged from 96 to 57,501, with a total of 86,575 individuals. The quality assessment of the 15 cross-sectional studies yielded scores ranging from 8 to 10.

Risk factors for LBP in the Chinese population

Seven risk factors were identified: cigarette smoking, body mass index (BMI) ≥ 28 kg/m², female sex, vibration exposure at work, working overtime, lack of exercise, and standing for long periods.

The certainty of the evidence for these seven risk factors was very low. Some risk factors, such as smoking, vibration exposure at work, and standing for a long time, might have had publication bias. The comprehensive results and the certainty of evidence assessment are presented in Table  2 . A detailed rating of the certainty of evidence assessment is provided in Additional File 4 . Begg’s and Egger’s tests are presented in Additional File 5 .

Cigarette smoking

Six studies assessing the correlation between smoking and LBP were included in this meta-analysis [ 18 , 36 , 37 , 38 , 45 , 46 ]. Comprehensive findings suggest that individuals in China who smoke are at a heightened risk of experiencing LBP compared with those who do not smoke (OR = 1.55; 95% CI: 1.15, 2.08, P  = 0.004, I 2  = 72%) (Fig.  2 ). Sensitivity analysis indicated significant heterogeneity regardless of which study was excluded.

Forest plot of cigarette smoking

BMI ≥ 28 kg/m²

Five studies evaluating the relationship between BMI ≥ 28 kg/m² and LBP were included [ 36 , 37 , 38 , 39 , 41 ]. The comprehensive findings suggest that individuals in the Chinese population with a BMI of 28 kg/m² or higher are at a heightened risk of experiencing LBP compared with those with a BMI below 28 kg/m² (OR = 4.51; 95% CI: 3.36, 6.07, P  < 0.00001, I 2  = 8%) (Fig.  3 ).

Forest plot of BMI ≥ 28 kg/m²

Five studies assessing the association between women and LBP were included [ 19 , 20 , 22 , 41 , 46 ]. The comprehensive findings suggest that within the Chinese population, women are more susceptible to LBP than men (OR = 1.54; 95% CI: 1.25, 1.90, P  < 0.0001, I 2  = 63%) (Fig.  4 ). Sensitivity analysis indicated that eliminating Liu et al.’s study could reduce I 2 to 0% (OR = 1.67; 95% CI: 1.44, 1.93, P  < 0.00001).

Forest plot of female sex

Vibration exposure at work

Five studies evaluating the relationship between work-related exposure to vibration sources and LBP were included in the meta-analysis [ 18 , 22 , 39 , 40 , 43 ]. The findings indicated that individuals in China who were exposed to vibration sources were at a higher risk of experiencing LBP than those not exposed to vibration sources (OR = 1.65; 95% CI: 1.16, 2.34, P  = 0.006, I 2  = 84%) (Fig.  5 ). Sensitivity analysis indicated that eliminating Jia et al.’s study could reduce I 2 to 8% (OR = 1.70; 95% CI: 1.42, 2.03, P  < 0.00001). This may be related to Jia’s definition of risk factors, which differs from those of other studies that only mention work involving vibrations. Jia’s study mentioned the use of vibration tools.

Forest plot of vibration exposure at work

Working overtime

Four studies assessing the association between extended working hours and LBP were included in the meta-analysis [ 36 , 38 , 42 , 44 ]. These findings suggest that individuals in China who work extended hours are more susceptible to LBP than those who work standard hours (OR = 2.57; 95% CI: 1.12, 5.91, P  < 0.03, I 2  = 85%) (Fig.  6 ). Sensitivity analysis indicated that eliminating the study by Xu et al. could reduce the I 2 to 0% (OR = 3.55; 95% CI: 2.24, 5.63, P  < 0.00001).

Forest plot of working overtime

Lack of exercise

Four studies assessing the association between exercise and LBP were included in the meta-analysis [ 37 , 38 , 39 , 40 ]. The comprehensive findings suggest that individuals in China who insufficiently engage in physical activity are at a greater risk of developing LBP than those who exercise regularly (OR = 2.48; 95% CI: 1.62, 3.78, P  < 0.0001, I 2  = 0%) (Fig.  7 ).

Forest plot of lack of exercise

Standing for long periods

Four studies assessing the association between prolonged standing and LBP were included [ 18 , 19 , 20 , 44 ]. The comprehensive findings indicate that prolonged standing is not a risk factor for LBP in the Chinese population (OR = 1.02; 95% CI: 0.82, 1.26, P  = 0.88, I 2  = 73%) (Fig.  8 ). Sensitivity analysis indicated that eliminating Jia’s study could reduce the I 2 to 0% (OR = 1.10; 95% CI: 0.94, 1.30, P  = 0.24).

Forest plot of standing for long periods

LBP is a common clinical problem in the Chinese population. Limited studies on LBP risk factors exist in China, and their results vary widely. Most studies have only explored the risk factors for LBP in specific occupational and regional populations. For instance, the study participants of Yue et al. [ 20 ] and Yao et al. [ 53 ] focused on Chinese teachers and adolescents, while Barrero et al. [ 43 ] only focused on individuals from rural areas. The risk factors they present have inherent limitations and do not apply to the entire Chinese population. Therefore, we conducted a systematic review to identify the risk factors that may cause LBP in the Chinese population. Seven risk factors were identified: smoking, BMI ≥ 28 kg/m², female sex, vibration exposure at work, working overtime, lack of exercise, and prolonged standing. Among them, prolonged standing was not related to the occurrence of LBP, which may be owing to different occupations and research studies conducted. Wong et al. found that female sex, obesity, and smoking were risk factors for LBP [ 54 ]. A LBP study among African school teachers found that lack of exercise and female sex are risk factors for LBP [ 55 ]. Jia et al.’s study found that vibration exposure at work and working overtime were risk factors for LBP [ 18 ]. These results are consistent with those of the present study.

Smoking and LBP are global public health concerns. Numerous studies [ 56 , 57 , 58 ] indicate that smoking increases the risk of LBP. Using a passive smoking model in rats, Nemoto et al. [ 56 ] found cracks, tears, and dislocations in the intervertebral discs. A recent study [ 58 ] has also shown that smoking and tetramer tryptase accelerate intervertebral disc degeneration by inducing methyltransferase 14-mediated dishevelled-axin domain-containing 1 m6 modifications. Smokers experience significantly greater levels of lumbar pain and dysfunction than non-smokers [ 57 ]. The greater the daily tobacco intake, the more pronounced the LBP. Therefore, to prevent the onset of LBP, Chinese individuals are advised to quit smoking or reduce the frequency of smoking.

BMI ≥ 28 kg/m 2 is a risk factor for LBP in the Chinese population. Adipose tissue due to obesity can release several adipokines (including leptin, resistin, and adiponectin) as well as proinflammatory cytokines such as interleukin-1β, interleukin-6, and tumour necrosis factor-α [ 59 ]. Leptin can accelerate the calcification of hyaline cartilage in the cartilaginous endplate, interfering with the transport of nutrients to disc cells [ 60 ]. Resistin expression in normal intervertebral discs is low but increases during intervertebral disc degeneration. In intervertebral disc tissues, resistin can activate nuclear factor-κB and p38 mitogen-activated protein kinase, followed by resistin binding to toll-like receptor 4 and increasing chemokine ligand 4 expression. This promotes the infiltration of macrophages [ 61 ]. However, the correlation between adiponectin level and LBP remains unclear. All these molecules may cause low-grade inflammation and have been shown to exert detrimental effects on nucleus pulposus and annulus fibrosus cells in vitro [ 62 ]. Fortunately, obesity can be modified through exercise and dietary management. Individuals with obesity should consider appropriate weight management strategies. Moreover, there are variations in the risk of LBP across sex groups. Women are at a higher risk of developing LBP than men, and patients with LBP exhibit poor dynamic postural control [ 63 ]. This may be attributed to the additional housework that women perform and their relatively low muscle strength. Women, as a group susceptible to LBP, should prioritise enhancing self-management awareness and mitigating LBP stemming from intrinsic factors.

A previous study showed that whole-body vibration can lead to compression, stretching, rotation, and spine flexion, all of which involve back muscles and cause fatigue [ 64 ]. Studies of the erector spinae found that electromyography signals increased during whole-body vibration, resulting in a decrease in the signal frequency of muscle fatigue, mainly at the resonance frequency of 5 Hz [ 65 , 66 , 67 ]. Kim et al. and Burström et al. concluded that irregular whole-body vibrations are closely associated with musculoskeletal disorders, particularly LBP onset [ 68 , 69 ]. Moreover, our previous research [ 70 ] indicated that vibration therapy remains a viable treatment for LBP, which may be closely related to vibration frequency and amplitude.

The reality many people face is the long working hours they must endure. Individuals are susceptible to musculoskeletal disorders in prolonged and high-intensity work environments, leading to an increased risk of LBP. People who frequently work overtime should be vigilant in preventing and managing this condition. In addition, extended working hours can lead to sedentary behaviour, a fixed posture at work, and prolonged neck forward tilt among professionals working in offices and drivers. A positive correlation exists between sedentary time and two common acute phase reactants, C-reactive protein and fibrinogen [ 71 , 72 ]. Sedentary behaviour also has a detrimental impact on systemic inflammation [ 71 , 72 ]. Compared with men, the level of inflammation in women is more influenced by sedentary behaviour [ 71 , 72 ]. Sedentary behaviour may also reduce bone density, decrease flexibility, and promote weight gain [ 59 ]. Furthermore, all participants in this study were adults, and no consideration was given to children. An Iranian meta-analysis [ 73 ] suggests that various forms of sedentary behaviour (such as prolonged TV viewing or electronic device use) may also contribute to LBP in children.

This study suggests that a lack of exercise may be a risk factor for LBP. As work and life pressures grow in China, ensuring regular physical activity for industry workers, such as factory employees, office staff, and healthcare professionals, has become challenging. A meta-analysis in China also suggested that Taijiquan, Pilates, sling and core stability exercises can improve LBP symptoms [ 74 ]. Taijiquan, a traditional Chinese sport, can enhance joint flexibility and mobility, boost muscle strength and endurance, increase the tensile strength of ligaments and bursae, improve cardiopulmonary function, and alleviate stress and anxiety [ 75 ]. In addition, Taijiquan can decrease the expression of serum B-type linalool peptides, enhance blood circulation, increase the metabolism of the lumbar spine, improve the absorption of calcium and other minerals by bone cells, and increase bone density in the lumbar region [ 76 ]. We recommend engaging in physical activity as a treatment or preventive measure for LBP.

Strengths and limitations

To our knowledge, this is the first meta-analysis to explore the risk factors for LBP in the Chinese population. We quantitatively assessed multiple studies on the risk factors for LBP in the Chinese population. With enhanced statistical precision and the resolution of inconsistencies found in previous studies, we arrived at more robust conclusions.

However, this study had inherent limitations. First, the included participants had various occupations and were from different regions of China, leading to heterogeneity in the results. Second, the included studies were cross-sectional, making it impossible to establish a causal relationship between the exposure factors and outcomes. Recall bias was also highly probable. Third, the limited literature included in this study on certain risk factors might have introduced bias into the research outcomes. Lastly, only Chinese and English language literature were included, with no gray literature retrieved, leading to a limited number of articles in the final analysis.

This study employed evidence-based medical research methods to analyse and explore the risk factors for LBP in the Chinese population. We found that smoking, BMI ≥ 28 kg/m², female sex, vibration exposure at work, working overtime, and lack of exercise may be risk factors for LBP in this population. However, because of the limited number of included studies and their cross-sectional design, causality could not be determined. The certainty of the evidence is also very low. Therefore, these findings should be interpreted with caution. Multicentre, high-quality studies should be conducted in the future. To reduce the prevalence of LBP, the Chinese government and hospitals must develop early screening programs and implement effective preventive and interventional measures.

Data availability

The datasets used and analyzed during the current study are available from the corresponding author on reasonable request.

Abbreviations

• Low back pain

Body mass index

95% Confidence interval

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1. Yang Yonghui Famous Traditional Chinese Medicine Studio of Anhui Province; 2. Anhui provincial-level regional Chinese medicine rehabilitation center construction project (Anhui Chinese medicine service secretary [2022] 34); 3. The fourth batch of national regional medical center construction project (Development and Reform Office of Society [2022] 887).

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Qiang Li, Leyun Peng, Yonghui Yang & Zongbao Wang

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QL and LYP conceived and designed the study. QL and YDW searched and selected relevant studies. QL and YDW extracted and interpreted data. QL and YDW analyzed the data. QL and LYP wrote the paper. QL, YHY, and ZBW revised the manuscript. All authors read and approved the final manuscript.

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Li, Q., Peng, L., Wang, Y. et al. Risk factors for low back pain in the Chinese population: a systematic review and meta-analysis. BMC Public Health 24 , 1181 (2024). https://doi.org/10.1186/s12889-024-18510-0

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Received : 29 November 2023

Accepted : 03 April 2024

Published : 26 April 2024

DOI : https://doi.org/10.1186/s12889-024-18510-0

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