systematic literature review introduction example

How to Write a Systematic Review Introduction

Automate every stage of your literature review to produce evidence-based research faster and more accurately.

How to write an introduction of a systematic review.

For anyone who has experience working on any sort of study, be it a review, thesis, or even just an academic paper – writing an introduction shouldn’t be a foreign concept. It generally follows the same rules, requiring it to give the readers the context of the study explaining what the review is all about: the topic it tackles, why the study was performed and the goals of its findings.

That said, most systematic reviews are governed by two guidelines that help improve the reporting of the research. These are the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement and the Cochrane handbook. Both have specifications on how to write the report, including the introduction. Look at a systematic review example , and you’ll find that it uses either one of these frameworks.

PRISMA Statement vs. Cochrane Guidelines

Learn more about distillersr.

(Article continues below)

What Is The Right Length Of A Systematic Review Introduction?

There’s no hard and fast rule about the length of a systematic review introduction. However, it’s best to keep it concise. Limit it to just two to four paragraphs, not exceeding one full page. Don’t worry, you’ll have the rest of the paper to fill with data!

What To Include In A Systematic Review Introduction

Whether or not you’re following writing guidelines, here are some pieces of information that you should include in your systematic review introduction:

Give background information about the review, including what’s already known about the topic and what you’re attempting to discover with your findings.

Definitions

This is optional, but if your review is dealing with important terms and concepts that require defining beforehand for better understanding on the readers’ part, add them to your introduction.

Delve a little into why the study topic is important, and why a systematic review must be done for it. This prompts a discussion about the knowledge gaps, a lack of cohesion in existing studies, and the potential implications of the review.

Research Question

Introduce your topic, specifically the research question that’s driving the study. Be sure that it’s new, focused, specific, and answerable, and that it ties together with your conclusion later on.

3 Reasons to Connect

Systematic Literature Reviews: An Introduction

• Proceedings of the Design Society International Conference on Engineering Design 1(1):1633-1642
• 1(1):1633-1642
• CC BY-NC-ND 4.0
• Conference: International Conference on Engineering Design 2019

• CentraleSupélec

Abstract and Figures

Discover the world's research

• 25+ million members
• 160+ million publication pages
• 2.3+ billion citations

• Husnia Sholihatin Amri
• Yetty Dwi Lestari
• Ronald Aloysius Romein
• Glenny Chudra
• Elsa Nandita
• Yahfizham Yahfizham

• Rungroj Wongmahasiri

• Tina Kartika

• Khanh Luong

• Hannah Gately

• Ryan Alshaikh
• Akmal Abdelfatah
• DESIGN STUD

• BMC MED RES METHODOL

• Martin Stacey

• L. Shamseer
• David Moher
• Alessandro Liberati

• David Jones

• J CLEAN PROD

• Alissa Kendall
• Recruit researchers
• Join for free
• Login Email Tip: Most researchers use their institutional email address as their ResearchGate login Password Forgot password? Keep me logged in Log in or Continue with Google Welcome back! Please log in. Email · Hint Tip: Most researchers use their institutional email address as their ResearchGate login Password Forgot password? Keep me logged in Log in or Continue with Google No account? Sign up

How to write a literature review introduction (+ examples)

The introduction to a literature review serves as your reader’s guide through your academic work and thought process. Explore the significance of literature review introductions in review papers, academic papers, essays, theses, and dissertations. We delve into the purpose and necessity of these introductions, explore the essential components of literature review introductions, and provide step-by-step guidance on how to craft your own, along with examples.

Why you need an introduction for a literature review

In academic writing , the introduction for a literature review is an indispensable component. Effective academic writing requires proper paragraph structuring to guide your reader through your argumentation. This includes providing an introduction to your literature review.

It is imperative to remember that you should never start sharing your findings abruptly. Even if there isn’t a dedicated introduction section .

When you need an introduction for a literature review

There are three main scenarios in which you need an introduction for a literature review:

What to include in a literature review introduction

It is crucial to customize the content and depth of your literature review introduction according to the specific format of your academic work.

In practical terms, this implies, for instance, that the introduction in an academic literature review paper, especially one derived from a systematic literature review , is quite comprehensive. Particularly compared to the rather brief one or two introductory sentences that are often found at the beginning of a literature review section in a standard academic paper. The introduction to the literature review chapter in a thesis or dissertation again adheres to different standards.

Academic literature review paper

The introduction of an academic literature review paper, which does not rely on empirical data, often necessitates a more extensive introduction than the brief literature review introductions typically found in empirical papers. It should encompass:

Regular literature review section in an academic article or essay

In a standard 8000-word journal article, the literature review section typically spans between 750 and 1250 words. The first few sentences or the first paragraph within this section often serve as an introduction. It should encompass:

In some cases, you might include:

Introduction to a literature review chapter in thesis or dissertation

Some students choose to incorporate a brief introductory section at the beginning of each chapter, including the literature review chapter. Alternatively, others opt to seamlessly integrate the introduction into the initial sentences of the literature review itself. Both approaches are acceptable, provided that you incorporate the following elements:

Examples of literature review introductions

Example 1: an effective introduction for an academic literature review paper.

To begin, let’s delve into the introduction of an academic literature review paper. We will examine the paper “How does culture influence innovation? A systematic literature review”, which was published in 2018 in the journal Management Decision.

Example 2: An effective introduction to a literature review section in an academic paper

The second example represents a typical academic paper, encompassing not only a literature review section but also empirical data, a case study, and other elements. We will closely examine the introduction to the literature review section in the paper “The environmentalism of the subalterns: a case study of environmental activism in Eastern Kurdistan/Rojhelat”, which was published in 2021 in the journal Local Environment.

The paper begins with a general introduction and then proceeds to the literature review, designated by the authors as their conceptual framework. Of particular interest is the first paragraph of this conceptual framework, comprising 142 words across five sentences:

Thus, the author successfully introduces the literature review, from which point onward it dives into the main concept (‘subalternity’) of the research, and reviews the literature on socio-economic justice and environmental degradation.

Examples 3-5: Effective introductions to literature review chapters

Numerous universities offer online repositories where you can access theses and dissertations from previous years, serving as valuable sources of reference. Many of these repositories, however, may require you to log in through your university account. Nevertheless, a few open-access repositories are accessible to anyone, such as the one by the University of Manchester . It’s important to note though that copyright restrictions apply to these resources, just as they would with published papers.

Master’s thesis literature review introduction

Phd thesis literature review chapter introduction, phd thesis literature review introduction.

The last example is the doctoral thesis Metacognitive strategies and beliefs: Child correlates and early experiences Chan, K. Y. M. (Author). 31 Dec 2020 . The author clearly conducted a systematic literature review, commencing the review section with a discussion of the methodology and approach employed in locating and analyzing the selected records.

Steps to write your own literature review introduction

Master academia, get new content delivered directly to your inbox, the best answers to "what are your plans for the future", 10 tips for engaging your audience in academic writing, related articles, 37 creative ways to get motivation to study, minimalist writing for a better thesis, separating your self-worth from your phd work, how to develop an awesome phd timeline step-by-step.

Reference management. Clean and simple.

How to write a systematic literature review [9 steps]

What is a systematic literature review?

Where are systematic literature reviews used, what types of systematic literature reviews are there, how to write a systematic literature review, 1. decide on your team, 2. formulate your question, 3. plan your research protocol, 4. search for the literature, 5. screen the literature, 6. assess the quality of the studies, 7. extract the data, 8. analyze the results, 9. interpret and present the results, registering your systematic literature review, frequently asked questions about writing a systematic literature review, related articles.

A systematic literature review is a summary, analysis, and evaluation of all the existing research on a well-formulated and specific question.

Put simply, a systematic review is a study of studies that is popular in medical and healthcare research. In this guide, we will cover:

• the definition of a systematic literature review
• the purpose of a systematic literature review
• the different types of systematic reviews
• how to write a systematic literature review

➡️ Visit our guide to the best research databases for medicine and health to find resources for your systematic review.

Systematic literature reviews can be utilized in various contexts, but they’re often relied on in clinical or healthcare settings.

Medical professionals read systematic literature reviews to stay up-to-date in their field, and granting agencies sometimes need them to make sure there’s justification for further research in an area. They can even be used as the starting point for developing clinical practice guidelines.

A classic systematic literature review can take different approaches:

• Effectiveness reviews assess the extent to which a medical intervention or therapy achieves its intended effect. They’re the most common type of systematic literature review.
• Diagnostic test accuracy reviews produce a summary of diagnostic test performance so that their accuracy can be determined before use by healthcare professionals.
• Experiential (qualitative) reviews analyze human experiences in a cultural or social context. They can be used to assess the effectiveness of an intervention from a person-centric perspective.
• Costs/economics evaluation reviews look at the cost implications of an intervention or procedure, to assess the resources needed to implement it.
• Etiology/risk reviews usually try to determine to what degree a relationship exists between an exposure and a health outcome. This can be used to better inform healthcare planning and resource allocation.
• Psychometric reviews assess the quality of health measurement tools so that the best instrument can be selected for use.
• Prevalence/incidence reviews measure both the proportion of a population who have a disease, and how often the disease occurs.
• Prognostic reviews examine the course of a disease and its potential outcomes.
• Expert opinion/policy reviews are based around expert narrative or policy. They’re often used to complement, or in the absence of, quantitative data.
• Methodology systematic reviews can be carried out to analyze any methodological issues in the design, conduct, or review of research studies.

Writing a systematic literature review can feel like an overwhelming undertaking. After all, they can often take 6 to 18 months to complete. Below we’ve prepared a step-by-step guide on how to write a systematic literature review.

• Decide on your team.
• Formulate your question.
• Plan your research protocol.
• Search for the literature.
• Screen the literature.
• Assess the quality of the studies.
• Extract the data.
• Analyze the results.
• Interpret and present the results.

When carrying out a systematic literature review, you should employ multiple reviewers in order to minimize bias and strengthen analysis. A minimum of two is a good rule of thumb, with a third to serve as a tiebreaker if needed.

You may also need to team up with a librarian to help with the search, literature screeners, a statistician to analyze the data, and the relevant subject experts.

Define your answerable question. Then ask yourself, “has someone written a systematic literature review on my question already?” If so, yours may not be needed. A librarian can help you answer this.

You should formulate a “well-built clinical question.” This is the process of generating a good search question. To do this, run through PICO:

• Patient or Population or Problem/Disease : who or what is the question about? Are there factors about them (e.g. age, race) that could be relevant to the question you’re trying to answer?
• Intervention : which main intervention or treatment are you considering for assessment?
• Comparison(s) or Control : is there an alternative intervention or treatment you’re considering? Your systematic literature review doesn’t have to contain a comparison, but you’ll want to stipulate at this stage, either way.
• Outcome(s) : what are you trying to measure or achieve? What’s the wider goal for the work you’ll be doing?

Now you need a detailed strategy for how you’re going to search for and evaluate the studies relating to your question.

The protocol for your systematic literature review should include:

• the objectives of your project
• the specific methods and processes that you’ll use
• the eligibility criteria of the individual studies
• how you plan to extract data from individual studies
• which analyses you’re going to carry out

For a full guide on how to systematically develop your protocol, take a look at the PRISMA checklist . PRISMA has been designed primarily to improve the reporting of systematic literature reviews and meta-analyses.

When writing a systematic literature review, your goal is to find all of the relevant studies relating to your question, so you need to search thoroughly .

This is where your librarian will come in handy again. They should be able to help you formulate a detailed search strategy, and point you to all of the best databases for your topic.

➡️ Read more on on how to efficiently search research databases .

The places to consider in your search are electronic scientific databases (the most popular are PubMed , MEDLINE , and Embase ), controlled clinical trial registers, non-English literature, raw data from published trials, references listed in primary sources, and unpublished sources known to experts in the field.

➡️ Take a look at our list of the top academic research databases .

Tip: Don’t miss out on “gray literature.” You’ll improve the reliability of your findings by including it.

Don’t miss out on “gray literature” sources: those sources outside of the usual academic publishing environment. They include:

• non-peer-reviewed journals
• pharmaceutical industry files
• conference proceedings
• pharmaceutical company websites
• internal reports

Gray literature sources are more likely to contain negative conclusions, so you’ll improve the reliability of your findings by including it. You should document details such as:

• The databases you search and which years they cover
• The dates you first run the searches, and when they’re updated
• Which strategies you use, including search terms
• The numbers of results obtained

➡️ Read more about gray literature .

This should be performed by your two reviewers, using the criteria documented in your research protocol. The screening is done in two phases:

• Pre-screening of all titles and abstracts, and selecting those appropriate
• Screening of the full-text articles of the selected studies

Make sure reviewers keep a log of which studies they exclude, with reasons why.

➡️ Visit our guide on what is an abstract?

Your reviewers should evaluate the methodological quality of your chosen full-text articles. Make an assessment checklist that closely aligns with your research protocol, including a consistent scoring system, calculations of the quality of each study, and sensitivity analysis.

The kinds of questions you'll come up with are:

• Were the participants really randomly allocated to their groups?
• Were the groups similar in terms of prognostic factors?
• Could the conclusions of the study have been influenced by bias?

Every step of the data extraction must be documented for transparency and replicability. Create a data extraction form and set your reviewers to work extracting data from the qualified studies.

Here’s a free detailed template for recording data extraction, from Dalhousie University. It should be adapted to your specific question.

Establish a standard measure of outcome which can be applied to each study on the basis of its effect size.

Measures of outcome for studies with:

• Binary outcomes (e.g. cured/not cured) are odds ratio and risk ratio
• Continuous outcomes (e.g. blood pressure) are means, difference in means, and standardized difference in means
• Survival or time-to-event data are hazard ratios

Design a table and populate it with your data results. Draw this out into a forest plot , which provides a simple visual representation of variation between the studies.

Then analyze the data for issues. These can include heterogeneity, which is when studies’ lines within the forest plot don’t overlap with any other studies. Again, record any excluded studies here for reference.

Consider different factors when interpreting your results. These include limitations, strength of evidence, biases, applicability, economic effects, and implications for future practice or research.

Apply appropriate grading of your evidence and consider the strength of your recommendations.

It’s best to formulate a detailed plan for how you’ll present your systematic review results. Take a look at these guidelines for interpreting results from the Cochrane Institute.

Before writing your systematic literature review, you can register it with OSF for additional guidance along the way. You could also register your completed work with PROSPERO .

Systematic literature reviews are often found in clinical or healthcare settings. Medical professionals read systematic literature reviews to stay up-to-date in their field and granting agencies sometimes need them to make sure there’s justification for further research in an area.

The first stage in carrying out a systematic literature review is to put together your team. You should employ multiple reviewers in order to minimize bias and strengthen analysis. A minimum of two is a good rule of thumb, with a third to serve as a tiebreaker if needed.

Your systematic review should include the following details:

A literature review simply provides a summary of the literature available on a topic. A systematic review, on the other hand, is more than just a summary. It also includes an analysis and evaluation of existing research. Put simply, it's a study of studies.

The final stage of conducting a systematic literature review is interpreting and presenting the results. It’s best to formulate a detailed plan for how you’ll present your systematic review results, guidelines can be found for example from the Cochrane institute .

An official website of the United States government

The .gov means it’s official. Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

The site is secure. The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

• Publications
• Account settings
• My Bibliography
• Collections
• Citation manager

Save citation to file

Email citation, add to collections.

• Create a new collection
• Add to an existing collection

Add to My Bibliography

Your saved search, create a file for external citation management software, your rss feed.

• Search in PubMed
• Search in NLM Catalog
• Add to Search

How to Do a Systematic Review: A Best Practice Guide for Conducting and Reporting Narrative Reviews, Meta-Analyses, and Meta-Syntheses

Affiliations.

• 1 Behavioural Science Centre, Stirling Management School, University of Stirling, Stirling FK9 4LA, United Kingdom; email: [email protected].
• 2 Department of Psychological and Behavioural Science, London School of Economics and Political Science, London WC2A 2AE, United Kingdom.
• 3 Department of Statistics, Northwestern University, Evanston, Illinois 60208, USA; email: [email protected].
• PMID: 30089228
• DOI: 10.1146/annurev-psych-010418-102803

Systematic reviews are characterized by a methodical and replicable methodology and presentation. They involve a comprehensive search to locate all relevant published and unpublished work on a subject; a systematic integration of search results; and a critique of the extent, nature, and quality of evidence in relation to a particular research question. The best reviews synthesize studies to draw broad theoretical conclusions about what a literature means, linking theory to evidence and evidence to theory. This guide describes how to plan, conduct, organize, and present a systematic review of quantitative (meta-analysis) or qualitative (narrative review, meta-synthesis) information. We outline core standards and principles and describe commonly encountered problems. Although this guide targets psychological scientists, its high level of abstraction makes it potentially relevant to any subject area or discipline. We argue that systematic reviews are a key methodology for clarifying whether and how research findings replicate and for explaining possible inconsistencies, and we call for researchers to conduct systematic reviews to help elucidate whether there is a replication crisis.

Keywords: evidence; guide; meta-analysis; meta-synthesis; narrative; systematic review; theory.

PubMed Disclaimer

Similar articles

• The future of Cochrane Neonatal. Soll RF, Ovelman C, McGuire W. Soll RF, et al. Early Hum Dev. 2020 Nov;150:105191. doi: 10.1016/j.earlhumdev.2020.105191. Epub 2020 Sep 12. Early Hum Dev. 2020. PMID: 33036834
• Summarizing systematic reviews: methodological development, conduct and reporting of an umbrella review approach. Aromataris E, Fernandez R, Godfrey CM, Holly C, Khalil H, Tungpunkom P. Aromataris E, et al. Int J Evid Based Healthc. 2015 Sep;13(3):132-40. doi: 10.1097/XEB.0000000000000055. Int J Evid Based Healthc. 2015. PMID: 26360830
• RAMESES publication standards: meta-narrative reviews. Wong G, Greenhalgh T, Westhorp G, Buckingham J, Pawson R. Wong G, et al. BMC Med. 2013 Jan 29;11:20. doi: 10.1186/1741-7015-11-20. BMC Med. 2013. PMID: 23360661 Free PMC article.
• A Primer on Systematic Reviews and Meta-Analyses. Nguyen NH, Singh S. Nguyen NH, et al. Semin Liver Dis. 2018 May;38(2):103-111. doi: 10.1055/s-0038-1655776. Epub 2018 Jun 5. Semin Liver Dis. 2018. PMID: 29871017 Review.
• Publication Bias and Nonreporting Found in Majority of Systematic Reviews and Meta-analyses in Anesthesiology Journals. Hedin RJ, Umberham BA, Detweiler BN, Kollmorgen L, Vassar M. Hedin RJ, et al. Anesth Analg. 2016 Oct;123(4):1018-25. doi: 10.1213/ANE.0000000000001452. Anesth Analg. 2016. PMID: 27537925 Review.
• The Association between Emotional Intelligence and Prosocial Behaviors in Children and Adolescents: A Systematic Review and Meta-Analysis. Cao X, Chen J. Cao X, et al. J Youth Adolesc. 2024 Aug 28. doi: 10.1007/s10964-024-02062-y. Online ahead of print. J Youth Adolesc. 2024. PMID: 39198344
• The impact of chemical pollution across major life transitions: a meta-analysis on oxidative stress in amphibians. Martin C, Capilla-Lasheras P, Monaghan P, Burraco P. Martin C, et al. Proc Biol Sci. 2024 Aug;291(2029):20241536. doi: 10.1098/rspb.2024.1536. Epub 2024 Aug 28. Proc Biol Sci. 2024. PMID: 39191283 Free PMC article.
• Target mechanisms of mindfulness-based programmes and practices: a scoping review. Maloney S, Kock M, Slaghekke Y, Radley L, Lopez-Montoyo A, Montero-Marin J, Kuyken W. Maloney S, et al. BMJ Ment Health. 2024 Aug 24;27(1):e300955. doi: 10.1136/bmjment-2023-300955. BMJ Ment Health. 2024. PMID: 39181568 Free PMC article. Review.
• Bridging disciplines-key to success when implementing planetary health in medical training curricula. Malmqvist E, Oudin A. Malmqvist E, et al. Front Public Health. 2024 Aug 6;12:1454729. doi: 10.3389/fpubh.2024.1454729. eCollection 2024. Front Public Health. 2024. PMID: 39165783 Free PMC article. Review.
• Strength of evidence for five happiness strategies. Puterman E, Zieff G, Stoner L. Puterman E, et al. Nat Hum Behav. 2024 Aug 12. doi: 10.1038/s41562-024-01954-0. Online ahead of print. Nat Hum Behav. 2024. PMID: 39134738 No abstract available.
• Search in MeSH

LinkOut - more resources

Full text sources.

• Ingenta plc
• Ovid Technologies, Inc.

Other Literature Sources

• scite Smart Citations

Miscellaneous

• NCI CPTAC Assay Portal
• Citation Manager

NCBI Literature Resources

MeSH PMC Bookshelf Disclaimer

The PubMed wordmark and PubMed logo are registered trademarks of the U.S. Department of Health and Human Services (HHS). Unauthorized use of these marks is strictly prohibited.

An official website of the United States government

The .gov means it’s official. Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

The site is secure. The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

• Publications
• Account settings

Preview improvements coming to the PMC website in October 2024. Learn More or Try it out now .

• Advanced Search
• Journal List
• v.112(1); Jan-Feb 2015

Systematically Reviewing the Literature: Building the Evidence for Health Care Quality

There are important research and non-research reasons to systematically review the literature. This article describes a step-by-step process to systematically review the literature along with links to key resources. An example of a graduate program using systematic literature reviews to link research and quality improvement practices is also provided.

Introduction

Systematic reviews that summarize the available information on a topic are an important part of evidence-based health care. There are both research and non-research reasons for undertaking a literature review. It is important to systematically review the literature when one would like to justify the need for a study, to update personal knowledge and practice, to evaluate current practices, to develop and update guidelines for practice, and to develop work related policies. 1 A systematic review draws upon the best health services research principles and methods to address: What is the state of the evidence on the selected topic? The systematic process enables others to reproduce the methods and to make a rational determination of whether to accept the results of the review. An abundance of articles on systematic reviews exist focusing on different aspects of systematic reviews. 2 – 9 The purpose of this article is to describe a step by step process of systematically reviewing the health care literature and provide links to key resources.

Systematic Review Process: Six Key Steps

Six key steps to systematically review the literature are outlined in Table 1 and discussed here.

Systematic Review Steps

1. Formulate the Question and Refine the Topic

When preparing a topic to conduct a systematic review, it is important to ask at the outset, “What exactly am I looking for?” Hopefully it seems like an obvious step, but explicitly writing a one or two sentence statement of the topic before you begin to search is often overlooked. It is important for several reasons; in particular because, although we usually think we know what we are searching for, in truth our mental image of a topic is often quite fuzzy. The act of writing something concise and intelligible to a reader, even if you are the only one who will read it, clarifies your thoughts and can inspire you to ask key questions. In addition, in subsequent steps of the review process, when you begin to develop a strategy for searching the literature, your topic statement is the ready raw material from which you can extract the key concepts and terminology for your strategies. The medical and related health literature is massive, so the more precise and specific your understanding of your information need, the better your results will be when you search.

2. Search, Retrieve, and Select Relevant Articles

The retrieval tools chosen to search the literature should be determined by the purpose of the search. Questions to ask include: For what and by whom will the information be used? A topical expert or a novice? Am I looking for a simple fact? A comprehensive overview on the topic? Exploration of a new topic? A systematic review? For the purpose of a systematic review of journal research in the area of health care, PubMed or Medline is the most appropriate retrieval tool to start with, however other databases may be useful ( Table 2 ). In particular, Google Scholar allows one to search the same set of articles as PubMed/MEDLINE, in addition to some from other disciplines, but it lacks a number of key advanced search features that a skilled searcher can exploit in PubMed/MEDLINE.

Examples of Electronic Bibliographic Databases Specific to Health Care

Note: These databases may be available through university or hospital library systems.

An effective way to search the literature is to break the topic into different “building blocks.” The building blocks approach is the most systematic and works the best in periodical databases such as PubMed/MEDLINE. The “blocks” in a “building blocks” strategy consist of the key concepts in the search topic. For example, let’s say we are interested in researching about mobile phone-based interventions for monitoring of patient status or disease management. We could break the topic into the following concepts or blocks: 1. Mobile phones, 2. patient monitoring, and 3. Disease management. Gather synonyms and related terms to represent each concept and match to available subject headings in databases that offer them. Organize the resulting concepts into individual queries. Run the queries and examine your results to find relevant items and suggest query modifications to improve your results. Revise and re-run your strategy based on your observations. Repeat this process until you are satisfied or further modifications produce no improvements. For example in Medline, these terms would be used in this search and combined as follows: cellular phone AND (ambulatory monitoring OR disease management), where each of the key word phrases is an official subject heading in the MEDLINE vocabulary. Keep detailed notes on the literature search, as it will need to be reported in the methods section of the systematic review paper. Careful noting of search strategies also allows you to revisit a topic in the future and confidently replicate the same results, with the addition of those subsequently published on your topic.

3. Assess Quality

There is no consensus on the best way to assess study quality. Many quality assessment tools include issues such as: appropriateness of study design to the research objective, risk of bias, generalizability, statistical issues, quality of the intervention, and quality of reporting. Reporting guidelines for most literature types are available at the EQUATOR Network website ( http://www.equator-network.org/ ). These guidelines are a useful starting point; however they should not be used for assessing study quality.

4. Extract Data and Information

Extract information from each eligible article into a standardized format to permit the findings to be summarized. This will involve building one or more tables. When making tables each row should represent an article and each column a variable. Not all of the information that is extracted into the tables will end up in the paper. All of the information that is extracted from the eligible articles will help you obtain an overview of the topic, however you will want to reserve the use of tables in the literature review paper for the more complex information. All tables should be introduced and discussed in the narrative of the literature review. An example of an evidence summary table is presented in Table 3 .

Example of an evidence summary table

Notes: BP = blood pressure, HbA1c = Hemoglobin A1c, Hypo = hypoglycemic, I = Internet, NS = not significant, PDA = personal digital assistant, QOL = quality of life, SMBG = self-monitored blood glucose, SMS = short message service, V = voice

5. Analyze and Synthesize Data and information

The findings from individual studies are analyzed and synthesized so that the overall effectiveness of the intervention can be determined. It should also be observed at this time if the effect of an intervention is comparable in different studies, participants, and settings.

6. Write the Systematic Review

The PRISMA 12 and ENTREQ 13 checklists can be useful resources when writing a systematic review. These uniform reporting tools focus on how to write coherent and comprehensive reviews that facilitate readers and reviewers in evaluating the relative strengths and weaknesses. A systematic literature review has the same structure as an original research article:

TITLE : The systematic review title should indicate the content. The title should reflect the research question, however it should be a statement and not a question. The research question and the title should have similar key words.

STRUCTURED ABSTRACT: The structured abstract recaps the background, methods, results and conclusion in usually 250 words or less.

INTRODUCTION: The introduction summarizes the topic or problem and specifies the practical significance for the systematic review. The first paragraph or two of the paper should capture the attention of the reader. It might be dramatic, statistical, or descriptive, but above all, it should be interesting and very relevant to the research question. The topic or problem is linked with earlier research through previous attempts to solve the problem. Gaps in the literature regarding research and practice should also be noted. The final sentence of the introduction should clearly state the purpose of the systematic review.

METHODS: The methods provide a specification of the study protocol with enough information so that others can reproduce the results. It is important to include information on the:

• Eligibility criteria for studies: Who are the patients or subjects? What are the study characteristics, interventions, and outcomes? Were there language restrictions?
• Literature search: What databases were searched? Which key search terms were used? Which years were searched?
• Study selection: What was the study selection method? Was the title screened first, followed by the abstract, and finally the full text of the article?
• Data extraction: What data and information will be extracted from the articles?
• Data analysis: What are the statistical methods for handling any quantitative data?

RESULTS: The results should also be well-organized. One way to approach the results is to include information on the:

• Search results: What are the numbers of articles identified, excluded, and ultimately eligible?
• Study characteristics: What are the type and number of subjects? What are the methodological features of the studies?
• Study quality score: What is the overall quality of included studies? Does the quality of the included studies affect the outcome of the results?
• Results of the study: What are the overall results and outcomes? Could the literature be divided into themes or categories?

DISCUSSION: The discussion begins with a nonnumeric summary of the results. Next, gaps in the literature as well as limitations of the included articles are discussed with respect to the impact that they have on the reliability of the results. The final paragraph provides conclusions as well as implications for future research and current practice. For example, questions for future research on this topic are revealed, as well as whether or not practice should change as a result of the review.

REFERENCES: A complete bibliographical list of all journal articles, reports, books, and other media referred to in the systematic review should be included at the end of the paper. Referencing software can facilitate the compilation of citations and is useful in terms of ensuring the reference list is accurate and complete.

The following resources may be helpful when writing a systematic review:

CEBM: Centre for Evidence-based Medicine. Dedicated to the practice, teaching and dissemination of high quality evidence based medicine to improve health care Available at: http://www.cebm.net/ .

CITING MEDICINE: The National Library of Medicine Style Guide for Authors, Editors, and Publishers. This resource provides guidance in compiling, revising, formatting, and setting reference standards. Available at http://www.ncbi.nlm.nih.gov/books/NBK7265/ .

EQUATOR NETWORK: Enhancing the QUAlity and Transparency Of health Research. The EQUATOR Network promotes the transparent and accurate reporting of research studies. Available at: http://www.equator-network.org/ .

ICMJE RECOMMENDATIONS: International Committee of Medical Journal Editors Recommendations for the Conduct, Reporting, Editing and Publication of Scholarly Work in Medical Journals. The ICJME recommendations are followed by a large number of journals. Available at: http://www.icmje.org/about-icmje/faqs/icmje-recommendations/ .

PRISMA STATEMENT: Preferred Reporting Items for Systematic Reviews and Meta-Analyses. Authors can utilize the PRISMA Statement checklist to improve the reporting of systematic reviews and meta-analyses. Available at: http://prisma-statement.org .

THE COCHRANE COLLABORATION: A reliable source for making evidence generated through research useful for informing decisions about health. Available at: http://www.cochrane.org/ .

Examples of Systematic Reviews To Link Research and Quality Improvement

Over the past 17 years more than 300 learners, including physicians, nurses, and health administrators have completed a course as part of a Master of Health Administration or a Master of Science in Health Informatics degree at the University of Missouri. An objective of the course is to educate health informatics and health administration professionals about how to utilize a systematic, scientific, and evidence-based approach to literature searching, appraisal, and synthesis. Learners in the course conduct a systematic review of the literature on a health care topic of their choosing that could suggest quality improvement in their organization. Students select topics that make sense in terms of their core educational competencies and are related to their work. The categories of topics include public health, leadership, information management, health information technology, electronic medical records, telehealth, patient/clinician safety, treatment/screening evaluation cost/finance, human resources, planning and marketing, supply chain, education/training, policies and regulations, access, and satisfaction. Some learners have published their systematic literature reviews 14 – 15 . Qualitative comments from the students indicate that the course is well received and the skills learned in the course are applicable to a variety of health care settings.

Undertaking a literature review includes identification of a topic of interest, searching and retrieving the appropriate literature, assessing quality, extracting data and information, analyzing and synthesizing the findings, and writing a report. A structured step-by-step approach facilitates the development of a complete and informed literature review.

Suzanne Austin Boren, PhD, MHA, (above) is Associate Professor and Director of Academic Programs, and David Moxley, MLIS, is Clinical Instructor and Associate Director of Executive Programs. Both are in the Department of Health Management and Informatics at the University of Missouri School of Medicine.

Contact: ude.iruossim.htlaeh@snerob

None reported.

Have a language expert improve your writing

Run a free plagiarism check in 10 minutes, automatically generate references for free.

• Knowledge Base
• Methodology
• Systematic Review | Definition, Examples & Guide

Systematic Review | Definition, Examples & Guide

Published on 15 June 2022 by Shaun Turney . Revised on 18 July 2024.

A systematic review is a type of review that uses repeatable methods to find, select, and synthesise all available evidence. It answers a clearly formulated research question and explicitly states the methods used to arrive at the answer.

They answered the question ‘What is the effectiveness of probiotics in reducing eczema symptoms and improving quality of life in patients with eczema?’

In this context, a probiotic is a health product that contains live microorganisms and is taken by mouth. Eczema is a common skin condition that causes red, itchy skin.

Table of contents

What is a systematic review, systematic review vs meta-analysis, systematic review vs literature review, systematic review vs scoping review, when to conduct a systematic review, pros and cons of systematic reviews, step-by-step example of a systematic review, frequently asked questions about systematic reviews.

A review is an overview of the research that’s already been completed on a topic.

What makes a systematic review different from other types of reviews is that the research methods are designed to reduce research bias . The methods are repeatable , and the approach is formal and systematic:

• Formulate a research question
• Develop a protocol
• Search for all relevant studies
• Apply the selection criteria
• Extract the data
• Synthesise the data
• Write and publish a report

Although multiple sets of guidelines exist, the Cochrane Handbook for Systematic Reviews is among the most widely used. It provides detailed guidelines on how to complete each step of the systematic review process.

Systematic reviews are most commonly used in medical and public health research, but they can also be found in other disciplines.

Systematic reviews typically answer their research question by synthesising all available evidence and evaluating the quality of the evidence. Synthesising means bringing together different information to tell a single, cohesive story. The synthesis can be narrative ( qualitative ), quantitative , or both.

Prevent plagiarism, run a free check.

Systematic reviews often quantitatively synthesise the evidence using a meta-analysis . A meta-analysis is a statistical analysis, not a type of review.

A meta-analysis is a technique to synthesise results from multiple studies. It’s a statistical analysis that combines the results of two or more studies, usually to estimate an effect size .

A literature review is a type of review that uses a less systematic and formal approach than a systematic review. Typically, an expert in a topic will qualitatively summarise and evaluate previous work, without using a formal, explicit method.

Although literature reviews are often less time-consuming and can be insightful or helpful, they have a higher risk of bias and are less transparent than systematic reviews.

Similar to a systematic review, a scoping review is a type of review that tries to minimise bias by using transparent and repeatable methods.

However, a scoping review isn’t a type of systematic review. The most important difference is the goal: rather than answering a specific question, a scoping review explores a topic. The researcher tries to identify the main concepts, theories, and evidence, as well as gaps in the current research.

Sometimes scoping reviews are an exploratory preparation step for a systematic review, and sometimes they are a standalone project.

A systematic review is a good choice of review if you want to answer a question about the effectiveness of an intervention , such as a medical treatment.

To conduct a systematic review, you’ll need the following:

• A precise question , usually about the effectiveness of an intervention. The question needs to be about a topic that’s previously been studied by multiple researchers. If there’s no previous research, there’s nothing to review.
• If you’re doing a systematic review on your own (e.g., for a research paper or thesis), you should take appropriate measures to ensure the validity and reliability of your research.
• Access to databases and journal archives. Often, your educational institution provides you with access.
• Time. A professional systematic review is a time-consuming process: it will take the lead author about six months of full-time work. If you’re a student, you should narrow the scope of your systematic review and stick to a tight schedule.
• Bibliographic, word-processing, spreadsheet, and statistical software . For example, you could use EndNote, Microsoft Word, Excel, and SPSS.

A systematic review has many pros .

• They minimise research b ias by considering all available evidence and evaluating each study for bias.
• Their methods are transparent , so they can be scrutinised by others.
• They’re thorough : they summarise all available evidence.
• They can be replicated and updated by others.

Systematic reviews also have a few cons .

• They’re time-consuming .
• They’re narrow in scope : they only answer the precise research question.

The 7 steps for conducting a systematic review are explained with an example.

Step 1: Formulate a research question

Formulating the research question is probably the most important step of a systematic review. A clear research question will:

• Allow you to more effectively communicate your research to other researchers and practitioners
• Guide your decisions as you plan and conduct your systematic review

A good research question for a systematic review has four components, which you can remember with the acronym PICO :

• Population(s) or problem(s)
• Intervention(s)
• Comparison(s)

You can rearrange these four components to write your research question:

• What is the effectiveness of I versus C for O in P ?

Sometimes, you may want to include a fourth component, the type of study design . In this case, the acronym is PICOT .

• Type of study design(s)
• The population of patients with eczema
• The intervention of probiotics
• In comparison to no treatment, placebo , or non-probiotic treatment
• The outcome of changes in participant-, parent-, and doctor-rated symptoms of eczema and quality of life
• Randomised control trials, a type of study design

Their research question was:

• What is the effectiveness of probiotics versus no treatment, a placebo, or a non-probiotic treatment for reducing eczema symptoms and improving quality of life in patients with eczema?

Step 2: Develop a protocol

A protocol is a document that contains your research plan for the systematic review. This is an important step because having a plan allows you to work more efficiently and reduces bias.

Your protocol should include the following components:

• Background information : Provide the context of the research question, including why it’s important.
• Research objective(s) : Rephrase your research question as an objective.
• Selection criteria: State how you’ll decide which studies to include or exclude from your review.
• Search strategy: Discuss your plan for finding studies.
• Analysis: Explain what information you’ll collect from the studies and how you’ll synthesise the data.

If you’re a professional seeking to publish your review, it’s a good idea to bring together an advisory committee . This is a group of about six people who have experience in the topic you’re researching. They can help you make decisions about your protocol.

It’s highly recommended to register your protocol. Registering your protocol means submitting it to a database such as PROSPERO or ClinicalTrials.gov .

Step 3: Search for all relevant studies

Searching for relevant studies is the most time-consuming step of a systematic review.

To reduce bias, it’s important to search for relevant studies very thoroughly. Your strategy will depend on your field and your research question, but sources generally fall into these four categories:

• Databases: Search multiple databases of peer-reviewed literature, such as PubMed or Scopus . Think carefully about how to phrase your search terms and include multiple synonyms of each word. Use Boolean operators if relevant.
• Handsearching: In addition to searching the primary sources using databases, you’ll also need to search manually. One strategy is to scan relevant journals or conference proceedings. Another strategy is to scan the reference lists of relevant studies.
• Grey literature: Grey literature includes documents produced by governments, universities, and other institutions that aren’t published by traditional publishers. Graduate student theses are an important type of grey literature, which you can search using the Networked Digital Library of Theses and Dissertations (NDLTD) . In medicine, clinical trial registries are another important type of grey literature.
• Experts: Contact experts in the field to ask if they have unpublished studies that should be included in your review.

At this stage of your review, you won’t read the articles yet. Simply save any potentially relevant citations using bibliographic software, such as Scribbr’s APA or MLA Generator .

• Databases: EMBASE, PsycINFO, AMED, LILACS, and ISI Web of Science
• Handsearch: Conference proceedings and reference lists of articles
• Grey literature: The Cochrane Library, the metaRegister of Controlled Trials, and the Ongoing Skin Trials Register
• Experts: Authors of unpublished registered trials, pharmaceutical companies, and manufacturers of probiotics

Step 4: Apply the selection criteria

Applying the selection criteria is a three-person job. Two of you will independently read the studies and decide which to include in your review based on the selection criteria you established in your protocol . The third person’s job is to break any ties.

To increase inter-rater reliability , ensure that everyone thoroughly understands the selection criteria before you begin.

If you’re writing a systematic review as a student for an assignment, you might not have a team. In this case, you’ll have to apply the selection criteria on your own; you can mention this as a limitation in your paper’s discussion.

You should apply the selection criteria in two phases:

• Based on the titles and abstracts : Decide whether each article potentially meets the selection criteria based on the information provided in the abstracts.
• Based on the full texts: Download the articles that weren’t excluded during the first phase. If an article isn’t available online or through your library, you may need to contact the authors to ask for a copy. Read the articles and decide which articles meet the selection criteria.

It’s very important to keep a meticulous record of why you included or excluded each article. When the selection process is complete, you can summarise what you did using a PRISMA flow diagram .

Next, Boyle and colleagues found the full texts for each of the remaining studies. Boyle and Tang read through the articles to decide if any more studies needed to be excluded based on the selection criteria.

When Boyle and Tang disagreed about whether a study should be excluded, they discussed it with Varigos until the three researchers came to an agreement.

Step 5: Extract the data

Extracting the data means collecting information from the selected studies in a systematic way. There are two types of information you need to collect from each study:

• Information about the study’s methods and results . The exact information will depend on your research question, but it might include the year, study design , sample size, context, research findings , and conclusions. If any data are missing, you’ll need to contact the study’s authors.
• Your judgement of the quality of the evidence, including risk of bias .

You should collect this information using forms. You can find sample forms in The Registry of Methods and Tools for Evidence-Informed Decision Making and the Grading of Recommendations, Assessment, Development and Evaluations Working Group .

Extracting the data is also a three-person job. Two people should do this step independently, and the third person will resolve any disagreements.

They also collected data about possible sources of bias, such as how the study participants were randomised into the control and treatment groups.

Step 6: Synthesise the data

Synthesising the data means bringing together the information you collected into a single, cohesive story. There are two main approaches to synthesising the data:

• Narrative ( qualitative ): Summarise the information in words. You’ll need to discuss the studies and assess their overall quality.
• Quantitative : Use statistical methods to summarise and compare data from different studies. The most common quantitative approach is a meta-analysis , which allows you to combine results from multiple studies into a summary result.

Generally, you should use both approaches together whenever possible. If you don’t have enough data, or the data from different studies aren’t comparable, then you can take just a narrative approach. However, you should justify why a quantitative approach wasn’t possible.

Boyle and colleagues also divided the studies into subgroups, such as studies about babies, children, and adults, and analysed the effect sizes within each group.

Step 7: Write and publish a report

The purpose of writing a systematic review article is to share the answer to your research question and explain how you arrived at this answer.

Your article should include the following sections:

• Abstract : A summary of the review
• Introduction : Including the rationale and objectives
• Methods : Including the selection criteria, search method, data extraction method, and synthesis method
• Results : Including results of the search and selection process, study characteristics, risk of bias in the studies, and synthesis results
• Discussion : Including interpretation of the results and limitations of the review
• Conclusion : The answer to your research question and implications for practice, policy, or research

To verify that your report includes everything it needs, you can use the PRISMA checklist .

Once your report is written, you can publish it in a systematic review database, such as the Cochrane Database of Systematic Reviews , and/or in a peer-reviewed journal.

A systematic review is secondary research because it uses existing research. You don’t collect new data yourself.

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.

Cite this Scribbr article

If you want to cite this source, you can copy and paste the citation or click the ‘Cite this Scribbr article’ button to automatically add the citation to our free Reference Generator.

Turney, S. (2024, July 17). Systematic Review | Definition, Examples & Guide. Scribbr. Retrieved 3 September 2024, from https://www.scribbr.co.uk/research-methods/systematic-reviews/

Is this article helpful?

Shaun Turney

Other students also liked, what is a literature review | guide, template, & examples, exploratory research | definition, guide, & examples, what is peer review | types & examples.

Have a language expert improve your writing

Run a free plagiarism check in 10 minutes, generate accurate citations for free.

• Knowledge Base

Methodology

• How to Write a Literature Review | Guide, Examples, & Templates

How to Write a Literature Review | Guide, Examples, & Templates

Published on January 2, 2023 by Shona McCombes . Revised on September 11, 2023.

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 that you can later apply to your paper, thesis, or dissertation topic .

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 summarize sources—it analyzes, synthesizes , and critically evaluates to give a clear picture of the state of knowledge on the subject.

Instantly correct all language mistakes in your text

Upload your document to correct all your mistakes in minutes

Table of contents

What is the purpose of 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, free lecture slides, other interesting articles, frequently asked questions, introduction.

• Quick Run-through
• Step 1 & 2

When you write a thesis , dissertation , or research paper , you will likely 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 its scholarly context
• Develop a theoretical framework and methodology for your research
• Position your work in relation to other researchers and theorists
• Show how your research addresses a gap or contributes to a debate
• Evaluate the current state of research and demonstrate your knowledge of the scholarly debates around your topic.

Writing literature reviews is a particularly important skill if you want to apply for graduate school or pursue a career in research. We’ve written a step-by-step guide that you can follow below.

Receive feedback on language, structure, and formatting

Professional editors proofread and edit your paper by focusing on:

• Academic style
• Vague sentences
• Style consistency

See an example

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 problem and questions .

Make a list of keywords

Start by creating a list of keywords related to your research question. 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 as 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 useful 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 also use boolean operators to help narrow down your search.

Make sure to 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.

You likely won’t be able to read absolutely everything that has been written on your topic, so it will be necessary to evaluate which sources are most relevant to your research question.

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?
• 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 use our template to summarize and evaluate sources you’re thinking about using. Click on either button below to download.

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 is important to keep track of your sources with citations to avoid plagiarism . It can be helpful to make an annotated bibliography , where you compile full citation 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.

Don't submit your assignments before you do this

The academic proofreading tool has been trained on 1000s of academic texts. Making it the most accurate and reliable proofreading tool for students. Free citation check included.

Try for free

To begin organizing your literature review’s argument and structure, be sure you 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 organizing the body of a literature review. 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 summarizing sources in order.

Try to analyze 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 organize 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.

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, you can follow these tips:

• 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 sentences to draw connections, comparisons and contrasts

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

When you’ve finished writing and revising your literature review, don’t forget to proofread thoroughly before submitting. Not a language expert? Check out Scribbr’s professional proofreading services !

This article has been adapted into lecture slides that you can use to teach your students about writing a literature review.

Scribbr slides are free to use, customize, and distribute for educational purposes.

Open Google Slides Download PowerPoint

If you want to know more about the research process , methodology , research bias , or statistics , make sure to check out some of our other articles with explanations and examples.

• Sampling methods
• Simple random sampling
• Stratified sampling
• Cluster sampling
• Likert scales
• Reproducibility

 Statistics

• Null hypothesis
• Statistical power
• Probability distribution
• Effect size
• Poisson distribution

Research bias

• Optimism bias
• Cognitive bias
• Implicit bias
• Hawthorne effect
• Anchoring bias
• Explicit bias

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 thesis, dissertation , or research paper , in order to situate your work in relation to existing knowledge.

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

• To familiarize 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 thesis or dissertation . After the introduction , it grounds your research in a scholarly field and leads directly to your theoretical framework or methodology .

A literature review is a survey of credible sources on a topic, often used in dissertations , theses, and research papers . Literature reviews give an overview of knowledge on a subject, helping you identify relevant theories and methods, as well as gaps in existing research. Literature reviews are set up similarly to other  academic texts , with an introduction , a main body, and a conclusion .

An  annotated bibliography is a list of  source references that has a short description (called an annotation ) for each of the sources. It is often assigned as part of the research process for a  paper .  

Cite this Scribbr article

If you want to cite this source, you can copy and paste the citation or click the “Cite this Scribbr article” button to automatically add the citation to our free Citation Generator.

McCombes, S. (2023, September 11). How to Write a Literature Review | Guide, Examples, & Templates. Scribbr. Retrieved September 3, 2024, from https://www.scribbr.com/dissertation/literature-review/

Is this article helpful?

Shona McCombes

Other students also liked, what is a theoretical framework | guide to organizing, what is a research methodology | steps & tips, how to write a research proposal | examples & templates, "i thought ai proofreading was useless but..".

I've been using Scribbr for years now and I know it's a service that won't disappoint. It does a good job spotting mistakes”

Writing An Introduction Of A Systematic Review Of Literature – A Quick Reference Table

Are Languages Still A Major Barrier To Global Science

English Language As A Barrier To Publish In High Impact Factor Journals – Quick Tips To Overcome

Systematic reviews are performed for synthesizing the evidence of multiple scientific investigations to answer a specific research question in a manner that is reproducible and transparent while seeking to include all published evidence on the topic followed evaluating the quality of this evidence. A Systematic review remains among the best forms of evidence and reduces the bias inherent in other methods. In the disciplines of public policy health and health sciences, systematic reviews have become the main methodology. Previously, some have provided that structure research ought to embrace the systematic review, but limited guidance is available. This section presented an overview of the various steps involved in performing a systematic review. This information should provide proper guidance for those who are conducting a systematic literature review (Davis, 2019 ).

Key characteristics of the systematic review

Identification of a research question, inclusion & exclusion criteria.

• Rigorous & systematic search of the literature
• Critical appraisal of included studies
• Data extraction and management
• Analysis & interpretation of results
• Report for publication

Different types of the systematic review

The systematic review mainly classified into three types, including (1) meta-analysis, (2) quantitative analysis and (3) qualitative analysis.

Meta-analysis:  A meta-analysis utilizes statistical methods to incorporate appraisals of impact from relevant studies that are independent yet comparable and outline them.

Quantitative:  To combine the results of 2 or more studies by using statistical analysis is called quantitative analysis.

Qualitative:  The qualitative analysis generally defined as the results of the relevant studies are summarized but not combined statistically.

Steps to be followed before drafting a systematic review

The identification of the research question is significant before undertaking a systematic review of literature . For instance, for what reason is this survey essential? What question should be replying?. There are a variety of frameworks/tools available for supporting this process such as SPIDER, PICOS/PICO, SPICE and PEO criteria. These kinds of frameworks help to break down the question into relevant subcomponents and map them to concepts, to derive a formalized search criterion. This step is essential for finding literature relevant to the subject (Jahan et al., 2016 ).

It is important to determine the eligibility criteria before starting the systematic review, including methods, study design, set criteria for the topic and the methodological quality of studies.

Guidelines for systematic review

Researchers widely follow the PRISMA guidelines in writing a systematic review . The PRISMA guidelines guide researchers on how to write a systematic review and that comprises a flow diagram and a 27-item checklist. A protocol of PRISMA guidelines including (1) Databases to be searched and additional sources (2) Keywords to be used in the search strategy (3) Limits applied to the search (4) Limits enforced to the search (5) Screening process (6) Data to be extracted and (7) Summary of data to be reported.

Screening of the articles

Some vital web source for the article screening including PubMed (Biomedical and life sciences topic), Medline (Biomedical information and life sciences), Embase (Biomedical information), Web of Science (Multidiscipline science), Biosis (Life sciences and biomedical topics), PsycINFO (Behaviour and mental health), SCOPUS (Life sciences, social sciences, physical sciences and health science), CINAHL (Cumulative Index to Nursing and Allied Health Literature), Cochrane Library (Database of systematic reviews ), CENTRAL (The Cochrane Central Register of Controlled Trials) and OpenGrey (Grey literature).

  Title and abstract screening: Initially, the title and abstract of the articles should be screened whether the title and abstract are relevant to the present research.

Full-text review: The remaining articles screened in a way mentioned above and the relevant sections are in their entire texts.

Data extraction: The essential data of the articles are extracted in a data extract sheet in a uniform and structured manner. The extraction sheets may differ based on the study’s purpose. Generally, the data extraction sheet containing the title of the article, study design, region, sample size, interventions and outcomes (Mueller et al., 2017 ).

Data analysis

The screened studies results can be analyzed by separating them based on the subthemes; themes often referred to as meta-synthesis (Siddaway et al., 2019 ).

The systematic review should be in the following structure

The abstract should contain a brief background, the aim of the study, a summary of the methodology, an overview of the results, conclusion and keywords.

Introduction

The chapter contains a brief background of the present study, followed by an overview of the aim and objectives of the research undertaken.

The methodology should be containing a full justification and explanation for the managing and searching steps. Specifically, the justification includes a thorough explanation about inclusion/exclusion criteria, search string, searching strategy, limitations, how studies were screened, data extraction protocol, method of quality assessment and statistical analysis .

The quantitative explanation and evidence must be given to the process of study exclusion/inclusion and summarized in a specific flow diagram. A characteristic of the study summary should be obtained, the sum of all studies, age range, mean/median and other characteristics.

To discuss the present study with the light of relevant research done in other studies. The main component of the discussion chapter should be focused on discussing and identifying the limitations of the studies included in the review.

The conclusion should be containing the summary of different aspects of the present study, and the results generated as well as the future scope of research and the findings derived from the present study.

Performing a systematic review of literature is quite complicated and time-consuming process which takes between 6 and 18 months on average depends on the study design. The guidelines mentioned above provide a good outline for conducting a systematic review of the literature. This framework especially is essential for early career researchers and medical students to enhance their writing knowledge on the systematic review of the literature.

Quick reference Table

Key points:

• A systematic review of the literature tends to be one of the most trusted sources of high-quality information for clinical decisions.
• Knowing the elements of a review will help practitioners evaluate their output more effectively.
• Many formal structures help organize and monitor evaluations, for which reproducibility is recommended.

pubrica-academy

Related posts.

Possible Data and Statistical Analyses for the Hypothetical Research Question based on Prospective Cohort Study 

Which is appropriate to use fixed-effect or random effect statistical model while conducting meta-analyses?

Effective strategies to monitor clinical risks using biostatistics

Comments are closed.

Systematic Reviews

• Introduction
• Guidelines and procedures
• Management tools
• Define the question
• Check the topic
• Determine inclusion/exclusion criteria
• Develop a protocol
• Identify keywords
• Databases and search strategies
• Grey literature
• Manage and organise
• Screen & Select
• Locate full text
• Extract data

Example reviews

• Examples of systematic reviews
• Accessing help This link opens in a new window
• Systematic Style Reviews Guide This link opens in a new window

Please choose the tab below for your discipline to see relevant examples.

For more information about how to conduct and write reviews, please see the Guidelines section of this guide.

• Health & Medicine
• Social sciences
• Vibration and bubbles: a systematic review of the effects of helicopter retrieval on injured divers. (2018).
• Nicotine effects on exercise performance and physiological responses in nicotine‐naïve individuals: a systematic review. (2018).
• Association of total white cell count with mortality and major adverse events in patients with peripheral arterial disease: A systematic review. (2014).
• Do MOOCs contribute to student equity and social inclusion? A systematic review 2014–18. (2020).
• Interventions in Foster Family Care: A Systematic Review. (2020).
• Determinants of happiness among healthcare professionals between 2009 and 2019: a systematic review. (2020).
• Systematic review of the outcomes and trade-offs of ten types of decarbonization policy instruments. (2021).
• A systematic review on Asian's farmers' adaptation practices towards climate change. (2018).
• Are concentrations of pollutants in sharks, rays and skates (Elasmobranchii) a cause for concern? A systematic review. (2020).
• << Previous: Write
• Next: Publish >>
• Last Updated: Aug 28, 2024 3:06 PM
• URL: https://libguides.jcu.edu.au/systematic-review

Teaching and Research guides

Systematic reviews.

• Starting the review
• About systematic reviews
• Research question
• Plan your search
• Sources to search
• Search example
• Screen and analyse

What to include

Introduction, discussion and conclusion.

• Further help

In general, the writing process for a systematic review is similar to the process of writing any other kind of review.

A systematic review should provide an answer to the research question , it is not a broad overview of current trends and gaps in research. The review should show the reader how the answer was found, and provide the results you have identified.

A systematic review must have a detailed methodology that describes the search process and the selection process. This is why careful documentation of the methodology is important. A reader of the review should be able to critically interpret the findings- to understand why sources were chosen, how they were assessed, and how conclusions were reached.

The structure of the systematic review differs from the narrative review or the traditional literature review that allows you to organise it to best support your argument. A systematic review should reflect the stages outlined in the protocol . With a systematic review reporting guidelines should be followed that help you identify what should be included in each section of the review. One such standard approach is PRISMA .

Although much time is invested in developing a search strategy and screening results, a systematic review is valued by the critical reflection and interpretation of the findings . Focus on analysing, not summarising. Use a critical analysis tool to assess the studies.

Your systematic review needs to tell a story, and it needs to clearly articulate how it provides meaningful and original advancement of the field .

The abstract provides an overview of the systematic review. It usually covers the following:

• A brief background (what we know and often the gap that the review will fill)
• The aim or hypothesis
• Summary of methods
• Summary of results
• Summary of conclusion (and sometimes recommendations).

Note that these points represent the general ‘story line’ seen in most systematic reviews: What we know (and perhaps what the gap is); what we set out to do; what we did; what we found; what this means.

The introduction provides an overview of the systematic review and enough contextual information for the reader to make sense of the remainder of the report. It usually covers the following:

• Background information to contextualise the review (what we already know about this area)
• Definitions of key terms and concepts if needed
• The rationale for the study (often in terms of a gap in knowledge that needs to be filled, a lack of agreement within the literature that needs to be resolved, or the potential implications of the findings)
• The aims and/or objectives (optional)
• The research question/s emanating from the rationale
• Additional information (Optional)

Note however, that these points are not always in this order. Some writers prefer to begin with the research questions, followed by the context, building to the rationale.

The  methods  section can be divided up into two main sections.

The first section describes how the literature search was conducted. This section may contain any of the following information: 

• The databases searched and whether any manual searches were completed 
• How search terms were identified 
• What terms were employed in the key word searches 
• If particular sections of articles were looked at during the search and collection stage i.e. titles, abstracts, table of contents ( note : the information in these sections may have informed the selection process) 

The second  section discusses the criteria for including or excluding studies. This section may include any of the following information:

• Your selection criteria
• How you identified relevant studies for further analysis 
• What articles you reviewed 
• What particular areas you looked at in the selected articles i.e. a relationship or association between two things (such as a genetic predisposition and a drug), the outcome measures of a health campaign, drug treatment, or clinical intervention, the differing impact of a particular drug or treatment. 

Details about the kind of systematic review undertaken, i.e. thematic analysis, might also be mentioned in the methods section.​

Broadly speaking, in the  results  section,  everything you have done so far needs to be presented.  This can include any of the following: ​

• briefly mention the  databases used for the searching
• identify the number of hits
• show how the articles were selected by title, abstract, table of contents or other procedures. 
• Overview of the kinds of studies selected for the review i.e. the types of methodologies or study designs used.
• where the trials were conducted
• treatment  duration
• details about participants
• similarities and differences in the way data was measured
• similar or different approaches to the same treatment or condition 
• Risk of bias across studies 
• the kinds of relationships or associations demonstrated by the studies
• frequency of positive or adverse effects of a particular treatment or drug
• the number of studies that found a positive correlation between two phenomena or found a causal relationship between two variables

Often, researchers will include tables in the Results section or Appendix to provide on overview of data found in the studies. Remember, tables in the Results section need to be explained fully.

A primary function of your discussion and conclusion is to help readers understand the main findings and implications of the review.

The following elements are commonly found in the discussion and conclusion sections. Note that the points listed are neither mandatory nor in any prescribed order.   

Discussion:

• Summary of main findings
• Interpretation of main findings (don’t repeat results)
• Strengths and weaknesses
• Comparison with previous review findings or general literature
• The degree to which the review answers the research question
• Whether the hypothesis was confirmed
• Limitations (e.g. biases, lack of methodological rigour or weak evidence in the articles)

Conclusion:

• Summary of how it answers the research question (the ‘take home’ message)
• Significance of the findings
• Reminder of the limitations
• Implications and recommendations for further research.

Separate or combined?

A key difference between a discussion and a conclusion relates to how specific or general the observations are. A discussion closely interprets results in the context of the review. A conclusion identifies the significance and the implications beyond the review. Some reviews present these as separately headed sections. Many reviews, however, present only one section using a combination of elements. This section may be headed either Discussion or Conclusion.

• << Previous: Synthesise
• Next: Further help >>

• Last Updated: Aug 30, 2024 4:17 PM
• URL: https://rmit.libguides.com/systematicreviews

• UNC Libraries
• HSL Academic Process
• Systematic Reviews

Systematic Reviews: Home

Created by health science librarians.

• Systematic review resources

What is a Systematic Review?

A simplified process map, how can the library help, publications by hsl librarians, systematic reviews in non-health disciplines, resources for performing systematic reviews.

• Step 1: Complete Pre-Review Tasks
• Step 2: Develop a Protocol
• Step 3: Conduct Literature Searches
• Step 4: Manage Citations
• Step 5: Screen Citations
• Step 6: Assess Quality of Included Studies
• Step 7: Extract Data from Included Studies
• Step 8: Write the Review

  Check our FAQ's

   Email us

   Call (919) 962-0800

   Make an appointment with a librarian

  Request a systematic or scoping review consultation

A systematic review is a literature review that gathers all of the available evidence matching pre-specified eligibility criteria to answer a specific research question. It uses explicit, systematic methods, documented in a protocol, to minimize bias , provide reliable findings , and inform decision-making.  ¹  

There are many types of literature reviews.

Before beginning a systematic review, consider whether it is the best type of review for your question, goals, and resources. The table below compares a few different types of reviews to help you decide which is best for you. 

• Scoping Review Guide For more information about scoping reviews, refer to the UNC HSL Scoping Review Guide.

• UNC HSL's Simplified, Step-by-Step Process Map A PDF file of the HSL's Systematic Review Process Map.
• Text-Only: UNC HSL's Systematic Reviews - A Simplified, Step-by-Step Process A text-only PDF file of HSL's Systematic Review Process Map.

The average systematic review takes 1,168 hours to complete. ¹   A librarian can help you speed up the process.

Systematic reviews follow established guidelines and best practices to produce high-quality research. Librarian involvement in systematic reviews is based on two levels. In Tier 1, your research team can consult with the librarian as needed. The librarian will answer questions and give you recommendations for tools to use. In Tier 2, the librarian will be an active member of your research team and co-author on your review. Roles and expectations of librarians vary based on the level of involvement desired. Examples of these differences are outlined in the table below.

• Request a systematic or scoping review consultation

The following are systematic and scoping reviews co-authored by HSL librarians.

Only the most recent 15 results are listed. Click the website link at the bottom of the list to see all reviews co-authored by HSL librarians in PubMed

Researchers conduct systematic reviews in a variety of disciplines.  If your focus is on a topic outside of the health sciences, you may want to also consult the resources below to learn how systematic reviews may vary in your field.  You can also contact a librarian for your discipline with questions.

• EPPI-Centre methods for conducting systematic reviews The EPPI-Centre develops methods and tools for conducting systematic reviews, including reviews for education, public and social policy.

Environmental Topics

• Collaboration for Environmental Evidence (CEE) CEE seeks to promote and deliver evidence syntheses on issues of greatest concern to environmental policy and practice as a public service

Social Sciences

• Siddaway AP, Wood AM, Hedges LV. How to Do a Systematic Review: A Best Practice Guide for Conducting and Reporting Narrative Reviews, Meta-Analyses, and Meta-Syntheses. Annu Rev Psychol. 2019 Jan 4;70:747-770. doi: 10.1146/annurev-psych-010418-102803. A resource for psychology systematic reviews, which also covers qualitative meta-syntheses or meta-ethnographies
• The Campbell Collaboration

Social Work

Software engineering

• Guidelines for Performing Systematic Literature Reviews in Software Engineering The objective of this report is to propose comprehensive guidelines for systematic literature reviews appropriate for software engineering researchers, including PhD students.

Sport, Exercise, & Nutrition

• Application of systematic review methodology to the field of nutrition by Tufts Evidence-based Practice Center Publication Date: 2009
• Systematic Reviews and Meta-Analysis — Open & Free (Open Learning Initiative) The course follows guidelines and standards developed by the Campbell Collaboration, based on empirical evidence about how to produce the most comprehensive and accurate reviews of research

• Systematic Reviews by David Gough, Sandy Oliver & James Thomas Publication Date: 2020

Updating reviews

• Updating systematic reviews by University of Ottawa Evidence-based Practice Center Publication Date: 2007
• Next: Step 1: Complete Pre-Review Tasks >>
• Last Updated: Jul 15, 2024 4:55 PM
• URL: https://guides.lib.unc.edu/systematic-reviews

• Open access
• Published: 31 August 2024

Linking abnormal fat distribution with HFpEF and diastolic dysfunction: a systematic review, meta-analysis, and meta-regression of observational studies

• Zhenyue Fu 1 , 2   na1 ,
• Yajiao Wang 1   na1 ,
• Yuxin Wang 1   na1 ,
• Shuqing Shi 1 ,
• Yumeng Li 1 ,
• Bingxuan Zhang 1 ,
• Huaqin Wu 3 &
• Qingqiao Song 1  

Lipids in Health and Disease volume  23 , Article number:  277 ( 2024 ) Cite this article

Metrics details

The global prevalence of obesity has escalated into a formidable health challenge intricately linked with the risk of developing cardiac diastolic disfunction and heart failure with preserved ejection fraction (HFpEF). Abnormal fat distribution is potentially strongly associated with an increased risk of cardiac diastolic dysfunction, and we aimed to scrutinize and elucidate the correlation between them.

Following the Cochrane Handbook and PRISMA 2020 guidelines, we systematically reviewed the literature from PubMed, Embase, and Web of Science. We focused on studies reporting the mean and standard deviation (SD) of abnormal fat in HFpEF or cardiac diastolic dysfunction patients and the Pearson/Spearman correlation coefficients for the relationship between abnormal fat distribution and the risk of developing cardiac diastolic dysfunction. Data were standardized to the standard mean difference (SMD) and Fisher’s z value for meta-analysis.

After progressive filtering and selection, 63 studies (43,113 participants) were included in the quantitative analyses. Abnormal fat distribution was significantly greater in participants with cardiac diastolic dysfunction than in controls [SMD 0.88 (0.69, 1.08)], especially in epicardial adipose tissue [SMD 0.99 (0.73, 1.25)]. Abnormal fat distribution was significantly correlated with the risk of developing cardiac diastolic dysfunction [E/E’: 0.23 (0.18, 0.27), global longitudinal strain: r =-0.11 (-0.24, 0.02)]. Meta-regression revealed sample size as a potential heterogeneous source, and subgroup analyses revealed a stronger association between abnormal fat distribution and the risk of developing cardiac diastolic dysfunction in the overweight and obese population.

Abnormal fat distribution was significantly associated with the risk of developing cardiac diastolic dysfunction.

Trial registration

CRD42024543774.

Introduction

With the increasing popularity of sedentary lifestyles and high-calorie diets, obesity has become a serious social and public health problem [ 1 ]. In the United States, the incidence of overweight and obesity has escalated to 30.7% and 42.4%, respectively [ 2 ]. These alarming numbers are increasing and exerting a profound and detrimental impact on global health and economic stability [ 3 ]. A dose‒response meta-analysis revealed a 41% heightened in the risk of developing heart failure with each 5 kg/m² body mass index (BMI) increment, whereas the Framingham Heart Study reported a 44% increase in the risk of developing heart failure with preserved ejection fraction (HFpEF) with each 4.7 kg/m² BMI increment [ 4 , 5 ]. Obesity leads to impaired left ventricular diastolic function, myocardial stiffness, and reduced relaxation capacity, which results in volume expansion and elevated filling pressures. It is associated with abnormal fat distribution, resulting in excess systemic free fatty acid-mediated lipotoxicity and persistent microinflammation within cardiomyocytes [ 6 , 7 , 8 ]. Abnormal fat distribution refers to the abnormal deposition of fat in nonphysiological storage areas of the body, such as the liver, heart, pancreas, and skeletal muscle [ 9 , 10 , 11 ]. The connection between abnormal fat distribution and the risk of developing HFpEF is a burgeoning field in cardiovascular research. Studies have shown that visceral adipose tissue (VAT) and epicardial adipose tissue (EAT) are predictive of HFpEF and its associated cardiometabolic risks but not of heart failure with a reduced ejection fraction (HFrEF) [ 12 , 13 ]. NAFLD induces HFpEF through inflammation and abnormal arteriovenous haemodynamics, resulting in three subtypes: obstructive, metabolic, and advanced liver fibrosis HFpEF [ 14 ].

With advancements and iterations in imaging technology, the methods for assessing abnormal fat distribution have become more abundant. However, previous research has often been limited to specific populations or types of abnormal fat distribution, and comprehensive comparisons and evaluations of the relationships between different abnormal fat deposits and the risk of developing cardiac diastolic dysfunction (CDD) are lacking. For example, a study by Wu et al. explored a strong association between EAT and the risk of developing atrial and ventricular dysfunction in HFpEF patients [ 15 ]. Similarly, Chong et al. reported a significant correlation between EAT thickness and volume and the risk of developing adverse cardiovascular outcomes, including myocardial infarction, coronary revascularization, and atrial fibrillation [ 16 ]. In addition, Cho et al. reported that EAT, rather than VAT, is associated with the risk of developing left ventricular geometry and function deterioration [ 17 ]. Considering the differences and limitations of previous studies, the aim of the current study was to conduct a meta-analysis of observational studies to provide a thorough review and investigation into the correlation between abnormal fat distribution and the risk of developing CDD.

Materials and methods

The study was guided by the Cochrane Handbook [ 18 ] and was registered in the PROSPERO (CRD42024543774). The study was guided by the 27-item checklist outlined in the PRISMA 2020 guidelines [ 19 ]. Data retrieval, extraction, and analysis were undertaken by FZY and WYJ. When disagreements occurred, a consensus was achieved through discussions with SQQ.

Search strategy and inclusion criterion

FZY and WYJ searched the PubMed, Embase, and Web of Science from establishment date to 10 May 2024, with language restrictions to English, and the search strategy involved a combination of subject terms plus free words, as described in Supplement Appendix S2.

The inclusion criteria were constructed according to the PECOS principles and studies were included based on the following criteria:

Participants: individuals diagnosed with HFpEF or CDD and were older than 18 years.

Exposure: abnormal fat (VAT, EAT, pericardial adipose tissue (PAT), nonalcoholic fatty liver disease (NAFLD)).

Outcomes: E/A, E/E’, e, E, global circumferential strain (GCS), global longitudinal strain (GLS), the left ventricular end-diastolic volume (LVEDV) and left ventricular end-diastolic internal diameter (LVEDD).

Study design: observational clinical studies.

Studies were omitted based on the following criteria:

Reviews, abstracts, and case reports.

Publications in non-English languages; and.

Missing main outcomes.

Data extraction

Data were meticulously extracted and recorded in a standardized form via Microsoft Excel, capturing the following details: (1) basic information: first author, year, nationality/region, and study design; (2) baseline information: sample size, sex ratio, mean age, BMI, distribution of abnormal fat, and detection method; and (3) outcomes: reported quantitative measurements of abnormal fat (means with standard deviations (mean [SD])), correlation between abnormal fat distribution and the risk of developing cardiac diastolic function (Pearson and Spearman coefficients).

Study quality assessment

The Newcastle‒Ottawa Scale (NOS) was used to evaluate the quality of each study in the three dimensions: selectivity of the population, groups comparability, and outcome of the nonrandomized study. A cumulative score out of 9 was given, where scores of 7–9 signify high quality, 4–6 denote moderate quality, and below 4 indicates low quality [ 20 ].

Data analysis

Data processing.

The extracted data included the mean (SD) and Pearson/Spearman correlation coefficients. To standardize the data and mitigate the effects of differing units, measurement techniques, and calculation methods, we transformed the continuous variables into Cohen’s d standard mean differences (SMDs) with 95% confidence intervals (95% CIs). Additionally, we converted the Spearman correlation coefficients to their Pearson equivalents via the following formula [ 21 , 22 ]:

For data analysis, we translated the correlation coefficients into Z values via Fisher’s z-transformation, which approximates a normal distribution, and calculated their standard deviations (standard errors, SEs). An inverse Fisher transformation was then applied to derive the correlation coefficients and 95% Cis [ 23 , 24 ]. According to the established classification of correlation coefficients, we categorized absolute values into three ranges: below 0.3 for weak, from 0.3 to 0.7 for moderate, and above 0.7 for robust linear correlations [ 25 ]. Furthermore, we applied Cohen’s criteria to define small, moderate, and large effect sizes for the SMD at thresholds of 0.2, 0.5, and 0.8, respectively [ 26 ].

Combined effect sizes

The statistical analyses were performed via Stata 17.0 (College Station, USA). Owing to considerable heterogeneity, a random-effects model with restricted maximum likelihood estimation and Cohen’s statistic was used to synthesize the statistics. To identify the sources of heterogeneity, we conducted meta-regression and subgroup analyses, considering factors such as sample size, age, BMI, region, fat locations, detection methods, and study design.

Sensitivity analyses were executed via sequential elimination to identify and exclude the studies that exerted the most significant influence on the robustness of the findings. Publication bias was investigated via two complementary methods: (1) the contour-enhanced funnel plots, which were used to visually inspect the symmetry of the plot and the distribution intervals [ 27 ], and (2) the trim-and-fill method, which was used to iteratively determine whether the inclusion or exclusion of studies affected the direction of the results [ 28 ].

Study screening process

The initial search yielded 2,132 articles. After removing duplicates, 1,536 articles remained. We then removed 1,424 irrelevant articles on the basis of their titles and abstracts. After a thorough review of the remaining 112 articles, we ultimately included 63 articles.(Fig.  1 ).

Flowchart of study inclusion and screening

Description and quality assessment of the included studies

The systematic review encompassed 63 studies, comprising 43 cross-sectional studies, 9 case‒control studies, and 11 cohort studies with a total of 43,113 participants. The mean age fluctuated within the range of 29 to 73 years, with an overall weighted average of 57.84 years. The BMI fluctuated within the range of 22 to 43.7 kg/m 2 , with a weighted BMI of 27.08 kg/m 2 . Abnormal fat included EAT ( n  = 31), PAT ( n  = 8), VAT ( n  = 15), thigh adipose tissue ( n  = 1), and NAFLD ( n  = 10). (Table  1 ).

The quality assessment revealed that the NOS scores ranged from 7 to 9, indicating that all the studies were of high quality (Supplement Appendix S4).

Exploring the association between the risk of developing CDD and abnormal fat distribution based on the SMD

Fifteen studies reported quantitative measurements—such as thickness, area, or volume—of abnormal fat in participants presenting with CDD and included 4,533 participants (580 participants with CDD/HFpEF and 1106 controls). We calculate the combined effect size with the random-effects model and revealed a significant increase in abnormal fat distribution among CDD patients [SMD = 0.88(0.69, 1.08), P  < 0.05].

Subgroup analysis showed an association between EAT and CDD [SMD = 0.99(0.73, 1.25), P  < 0.05, I 2  = 80.4%]. Similarly, VAT had a moderate effect size [SMD = 0.74(0.38, 1.10), P  < 0.05, I 2  = 77%], and PAT had a smaller yet significant effect size [SMD = 0.51(0.18, 0.83), P  < 0.05] (Fig.  2 ).

Subgroup analysis linked abnormal fat distribution to CDD risk, based on the SMD

Exploring CDD and abnormal fat correlation via Pearson correlation

Mitral valve doppler ultrasound indices.

Using tissue Doppler ultrasound to detect diastolic mitral flow velocities and motion velocities, abnormal fat distribution had a weak positive correlation with E/E’ [ n  = 29, r  = 0.23 (0.18, 0.27), P  < 0.05], whereas it had a weak positive correlation with E [ n  = 7, r =-0.10(-0.24, 0.04), P  < 0.05)] and E/A [ n  = 16, r =-0.29(-0.37, -0.21), P  < 0.05] and a weak negative correlation with E [ n  = 23, r =-0.27(-0.35, -0.19), P  < 0.05] (Supplement Appendix S5).

An analysis of the different fat deposition locations revealed that NAFLD status had the strongest correlations with E/E’ ( r  = 0.32) and e ( r =-0.24), whereas EAT showed a strong negative correlation with E/A ( r =-0.32), and PAT similarly correlated negatively with with e ( r  = 0.32) (Table  2 ).

Myocardial strain

The speckle tracking technique is a sophisticated method that enables the tracking of echo signals throughout the cardiac cycle and reflects quantitative myocardial ventricular motion. GLS indicates the relative change in the length of the left ventricular myocardium along its long axis from end-diastole to end-systole. Conversely, the GCS indicates the relative change in the circumferential direction. Abnormal fat distribution was weakly correlated with myocardial strain [GLS n  = 17, r =-0.11(-0.24, 0.02), P  < 0.05] [GCS n  = 6, r =-0.19(-0.34, -0.03), P  < 0.05] (Supplement Appendix S5).

An analysis of the different abnormal fat deposition locations revealed that NAFLD status had the strongest correlation with GLS ( r =-0.18) and GCS ( r =-0.34), whereas VAT had a weak negative correlation with GLS ( r =-0.06) (Table  2 ).

LVEDd and LVEDV

Abnormal fat deposits had a weak positive correlation with LVEDd [ n  = 5, r  = 0.16 (-0.05, 0.38), P  < 0.05)] and LVEDV [ n  = 9, r  = 0.10 (-0.12, 0.31), P  < 0.05)] (Supplement Appendix S5).

An analysis of the different abnormal fat deposition locations revealed that NAFLD status had the strongest correlation with LVEDd ( r  = 0.24). Moreover, EAT and VAT were positively correlated with the LVEDV ( r  = 0.31), and surprisingly, NAFLD status was significantly negatively correlated with LVEDV ( r =-0.31).

Subgroup analysis and meta-regression

Meta-regression was used to assess the trend of a potential effect modifier by statistically combining the results through an integrated and quantitative approach [ 89 ]. The results showed that sample size may be a covariate, with the associations of abnormal fat distribution with E/E’ (Z=-2.68) and E/A (Z=-3.69) diminishing as the sample size increased. The strength of the association between abnormal fat distribution and the GCS score also tended to increase with age, BMI, and male sex (Supplement Appendix S7).

However, covariates in the meta-regression did not account for all of the observed heterogeneity, and subgroup analyses based on sample size, region, study design, age, BMI, and detection methods were conducted to detect heterogeneity. The aim was to delve deeper into the results, overcome the limitations associated with continuous variables, and identify the root causes of heterogeneity. The findings were as follows (Table  2 ):

In studies with larger sample sizes (> 1000 participants), the correlation coefficients for the associations of abnormal fat distribution with E/E’, E/A, and e’ were approximately half those reported in smaller studies (< 99 participants).

Compared with that in other demographic groups, the association between abnormal fat distribution and the risk of developing CDD was more pronounced in European populations (E/E’ r = 0.31, I²=54.81%).

Compared with that in normal weight patients, in overweight or obese patients, abnormal fat distribution was strongly correlated with abnormal mitral Doppler findings (E/E’ r  = 0.26, e r =-0.29) and impaired strain function (GLS r =-0.28, GCS r =-0.21).

When measured by ultrasound, abnormal fat distribution was significantly more strongly associated with the risk of developing CDD than other detection methods were.

Sensitivity analysis

A sequential elimination sensitivity analysis was conducted to validate the results’ robustness and reliability. During this process, the robustness of seven outcomes was affected. Upon eliminating those outlier studies and recalculating the combined effect sizes, no alteration was observed in the direction of the effects, which indicates the stability and dependability of the results. Notably, the large-sample studies conducted by Chiu et al. [ 47 ]. , Kostka et al. [ 53 ]. , and VanWagner et al. [ 50 ]. carried significant weight in the analysis and exerted a substantial influence on the combined effect sizes (Supplement Appendix S8).

Publication bias

The contour-enhanced plot classifies studies into three intervals: p values below 0.01, p values exceeding 0.05 0.05, and p values between 0.01 and 0.05. The central dark region, with p -values exceeding 0.05, indicates that the results of the studies in that area were not statistically significant. Most studies were symmetrical around the red estimated effect line (estimated θ IV ) or located in the black area. Nevertheless, a few studies showed asymmetry. By recombining the effect sizes via the trim-and-fill method, the direction of their estimates remained unchanged, suggesting that publication bias did not influence the robustness of the results (Supplement Appendix S9).

Overview of results

The advent of sophisticated detection methods has ushered in a new era of noninvasive assessment of whole-body and regional fat distribution. This has led to an increase in interest among scientists and clinicians in adipose tissue, particularly its implications for cardiovascular health [ 90 , 91 ]. To provide a systematic, exhaustive, and thorough review of the relationship between abnormal fat distribution and the risk of developing CDD, three electronic databases were searched, and 63 relevant articles were included (containing 43,113 participants).

According to these findings, two preliminary yet pivotal conclusions could be drawn. First, the quantification of abnormal fat (thickness, volume, or area) was elevated in participants with CDD or HFpEF compared with controls. Second, a noteworthy correlation was identified between abnormal fat distribution and the risk of developing CDD, and NAFLD and EAT appear to be most closely associated with CDD among different abnormal fat deposition locations.

Undoubtedly, considerable heterogeneity was uncovered in the present study, and meta-regression and subgroup analyses were employed to dissect potential effect modifiers. Meta-regression identified sample size as a significant modifier that impacts the correlation between abnormal fat distribution and diastolic function, including the E/E’ ratio and E/A. Studies with larger cohorts enhance the statistical robustness, minimize sampling error, and bolster the generalizability and credibility of the findings [ 92 ]. Subgroup analysis is a powerful tool that can be used to combine similar studies and identify sources of heterogeneity, distinguishing between clinical and assay-related heterogeneity [ 93 ]. Notably, the findings differed for different regions of abnormal fat. For example, EAT and NAFLD demonstrated robust negative correlations with diastolic function indices such as E/A and e’, whereas the correlation between VAT and diastolic function was weaker. Furthermore, a pronounced correlation between abnormal fat distribution and the risk of developing CDD was discovered, particularly in overweight or obese populations. This finding is consistent with previous findings that the obese phenotype is associated with severe diastolic dysfunction and all-cause mortality [ 94 ].

Abnormal fat distribution and potential mechanisms of CDD

Adipose tissue is a metabolically active endocrine organ that elicits local and systemic responses through the production of chemical messengers such as adipokines, proinflammatory cytokines, and chemokines. It communicates with all tissues and organs in autocrine, paracrine, and endocrine manners [ 95 , 96 ]. Adipose tissue can be categorized into brown adipose tissue (BAT) and white adipose tissue (WAT) on the basis of structural, phenotypic, and functional grounds [ 97 , 98 ]. WAT is composed of clusters of unilocular adipocytes that are pivotal for fat storage and mobilization and are intricately connected to lipid metabolism. The size of white adipocytes and their metabolic turnover rate are key factors in determining insulin sensitivity and cardiovascular metabolic abnormalities [ 99 ].

Abnormal fat can be deposited in various locations in the body and poses a threat to metabolic homeostasis and cardiovascular health. EAT is located between the myocardium and the pericardium and is composed of adipocytes, stromal cells, and resident inflammatory cells [ 100 ]. EAT transmits adipokines and cytokines to influence cardiomyocytes through a shared microcirculation, and its hypertrophic expansion exerts a direct compressive effect on the myocardium [ 101 , 102 ]. Advanced transcriptomics and proteomics have revealed the gene profiles of EAT involved in processes such as inflammation, thrombosis, and extracellular matrix remodelling [ 103 ]. Furthermore, proteomic analysis of EAT among HFpEF patients revealed that its biological processes are predominantly related to lipid metabolism disorders, inflammation, and mitochondrial dysfunction [ 104 ]. However, the correlations between different fat distributions and cardiovascular metabolic risk are not uniform. The Framingham Heart Study established a link between abnormal fat distribution, systemic inflammation, and cardiometabolic burden, with VAT emerging as a significant predictor of cardiovascular risk and PAT being correlated with coronary atherosclerosis [ 105 , 106 , 107 ]. Kranendonk et al. characterized PAT by its small adipocyte volume, dense capillary network, and elevated levels of inflammatory adipokines (such as epidermal growth factor, neurotrophic factors, IL-17, and monocyte chemotactic protein-1). In contrast, VAT is strongly associated with insulin resistance and metabolic syndrome [ 108 ]. The latest research suggests that NAFLD has a more significant association with HFpEF than with HFrEF on the basis of comorbid risk factors such as metabolic disorders, obesity and diabetes [ 29 , 30 ]. Individuals with NAFLD first experience a reduction in myocardial energy metabolism, including decreased glucose utilization, triglyceride deposition, and a decreased phosphocreatine: ATP ratio, which subsequently affects cardiac structure, including an enlarged left atrium, increased cardiac mass, and ultimately diastolic dysfunction [ 31 ]. Therefore, we systematically summarized the relevant clinical trials to clarify the effect of abnormal fat distribution on diastolic function.

Strengths and limitations

The results may provide some guidance for clinical practice. First, the findings suggest that abnormal fat may be a novel biomarker for the dynamic identification of HFpEF, and physicians can incorporate these biomarkers into their clinical assessments. Moreover, physicians and nursing staff can develop or recommend preventive strategies, such as lifestyle changes, dietary modifications, and physical activity, to reduce abnormal fat distribution among populations with cardiovascular disease.

However, this study still has limitations that cannot be resolved at present. 1). Study definition limitations: Many studies have concentrated on abnormal fat distribution, yet many have failed to distinguish between EAT and PAT. 2). Data heterogeneity and sensitivity: The results exhibited significant heterogeneity, with meta-regression and subgroup analysis indicating differences in fat distribution and sample size as likely causes. Although the sensitivity analysis revealed some irregularities, the overall direction of the effect remained consistent even after the studies were sequentially removed. Nevertheless, this continues to provoke inquiries regarding the reliability and credibility of the outcomes.

According to the available evidence, excessive accumulation of abnormal fat influences the risk of developing CDD. However, the persistent heterogeneity across studies prevents us from establishing a robust conclusion. Consequently, additional clinical data is needed to bolster and solidify the conclusions.

Availability of data and materials

Supplementary materials.

Data availability

No datasets were generated or analysed during the current study.

WHO. Obesity and overweight. https://www.who.int/news-room/fact-sheets/detail/obesity-and-overweight#:~:text=In%202022%2C%201%20in%208,million%20were%20living%20with%20obesity .

National Institute for Diabetes and Digestive and Kidney Diseases. Overweight & obesity statistics. http://www.niddk.nih.gov/health-information/health-statistics/overweight-obesity .

Caballero B. Humans against obesity: who will win? Adv Nutr. 2019;10:S4-9.

Article   PubMed   PubMed Central   Google Scholar  

Aune D, Sen A, Norat T, Janszky I, Romundstad P, Tonstad S, Vatten LJ. Body mass index, abdominal fatness, and heart failure incidence and mortality: a systematic review and dose-response meta-analysis of prospective studies. Circulation. 2016;133:639–49.

Article   PubMed   Google Scholar  

Ho JE, Lyass A, Lee DS, Vasan RS, Kannel WB, Larson MG, Levy D. Predictors of new-onset heart failure: differences in preserved versus reduced ejection fraction. Circ Heart Fail. 2013;6:279–86.

Gilden AH, Catenacci VA, Taormina JM. Obesity. Ann Intern Med. 2024:177.

Patel VB, Shah S, Verma S, Oudit GY. Epicardial adipose tissue as a metabolic transducer: role in heart failure and coronary artery disease. Heart Fail Rev. 2017;22:889–902.

Fontes-Carvalho R, Fontes-Oliveira M, Sampaio F, Mancio J, Bettencourt N, Teixeira M, Rocha Gonçalves F, Gama V, Leite-Moreira A. Influence of epicardial and visceral fat on left ventricular diastolic and systolic functions in patients after myocardial infarction. Am J Cardiol. 2014;114:1663–9.

Levelt E, Pavlides M, Banerjee R, Mahmod M, Kelly C, Sellwood J, Ariga R, Thomas S, Francis J, Rodgers C, et al. Ectopic and visceral fat deposition in lean and obese patients with type 2 diabetes. J Am Coll Cardiol. 2016;68:53–63.

Katsiki N, Mikhailidis DP, Mantzoros C. Abnormal peri-organ-intra-organ fat (APIFat) and rheumatoid arthritis: an under-investigated link for increased cardiovascular risk? Curr Vasc Pharmacol. 2020;18:249–53.

Article   PubMed   CAS   Google Scholar  

Della Pepa G, Salamone D, Testa R, Bozzetto L, Costabile G. Intrapancreatic fat deposition and nutritional treatment: the role of various dietary approaches. Nutr Rev. 2023. Online ahead of print.

Liu J, Yu Q, Li Z, Zhou Y, Liu Z, You L, Tao L, Dong Q, Zuo Z, Gao L, Zhang D. Epicardial adipose tissue density is a better predictor of cardiometabolic risk in HFpEF patients: a prospective cohort study. Cardiovasc Diabetol. 2023;22:45.

Article   PubMed   PubMed Central   CAS   Google Scholar  

Rao VN, Zhao D, Allison MA, Guallar E, Sharma K, Criqui MH, Cushman M, Blumenthal RS, Michos ED. Adiposity and incident heart failure and its subtypes: MESA (multi-ethnic study of atherosclerosis). JACC Heart Fail. 2018;6:999–1007.

Salah HM, Pandey A, Soloveva A, Abdelmalek MF, Diehl AM, Moylan CA, Wegermann K, Rao VN, Hernandez AF, Tedford RJ, et al. Relationship of nonalcoholic fatty liver disease and heart failure with preserved ejection fraction. JACC Basic Transl Sci. 2021;6:918–32.

Wu A, Yang Z, Zhang X, Lin Z, Lu H. Association between epicardial adipose tissue and left atrial and ventricular function in patients with heart failure: a systematic review and meta-analysis. Curr Probl Cardiol. 2023;48:101979.

Chong B, Jayabaskaran J, Ruban J, Goh R, Chin YH, Kong G, Ng CH, Lin C, Loong S, Muthiah MD, et al. Epicardial adipose tissue assessed by computed tomography and echocardiography are associated with adverse cardiovascular outcomes: a systematic review and meta-analysis. Circ Cardiovasc Imaging. 2023;16:e015159.

PubMed   Google Scholar  

Cho IJ, Lee SE, Pyun WB. Association of body adiposity with left ventricular concentric remodeling and diastolic dysfunction. Echocardiography. 2024;41:e15872.

Higgins JPT, Thomas J, Chandler J, Cumpston M, Li T, Page MJ, Welch VA (editors). Cochrane handbook for systematic reviews of interventions version 6.4 (updated August 2023). Cochrane, 2023. Available from www.training.cochrane.org/handbook .

Moher D, Liberati A, Tetzlaff J, Altman DG. Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement. PLoS Med. 2009;6: e1000097.

Stang A. Critical evaluation of the Newcastle-Ottawa scale for the assessment of the quality of nonrandomized studies in meta-analyses. Eur J Epidemiol. 2010;25:603–5.

Rupinski MT, Dunlap WP. Approximating Pearson product-moment correlations from Kendall’s tau and Spearman’s rho. Educ Psychol Meas. 1996;56:419–29.

Article   Google Scholar  

Peterson RA, Brown SP. On the use of beta coefficients in meta-analysis. J Appl Psychol. 2005;90:175–81.

McGrath TA, Alabousi M, Skidmore B, Korevaar DA, Bossuyt PMM, Moher D, Thombs B, McInnes MDF. Recommendations for reporting of systematic reviews and meta-analyses of diagnostic test accuracy: a systematic review. Syst Rev. 2017;6:194.

Corey DM, Dunlap WP, Burke MJ. Averaging correlations: expected values and bias in combined Pearson rs and Fisher’s z transformations. J Gen Psychol. 1998;125:245–61.

Ratner B. The correlation coefficient: its values range between + 1/–1, or do they? J Target Meas Anal Mark. 2009;17:139–42.

Cohen J. A power primer. Psychol Bull. 1992;112:155–9.

Peters JL, Sutton AJ, Jones DR, Abrams KR, Rushton L. Contour-enhanced meta-analysis funnel plots help distinguish publication bias from other causes of asymmetry. J Clin Epidemiol. 2008;61:991–6.

Viechtbauer W. Publication bias in meta-analysis: prevention, assessment and adjustments. Psychometrika. 2007;72:269–71.

Article   PubMed Central   Google Scholar  

Lin HH, Lee JK, Yang CY, Lien YC, Huang JW, Wu CK. Accumulation of epicardial fat rather than visceral fat is an independent risk factor for left ventricular diastolic dysfunction in patients undergoing peritoneal dialysis. Cardiovasc Diabetol. 2013;12.

Konishi M, Sugiyama S, Sugamura K, Nozaki T, Matsubara J, Akiyama E, Utsunomiya D, Matsuzawa Y, Yamashita Y, Kimura K, et al. Accumulation of pericardial fat correlates with left ventricular diastolic dysfunction in patients with normal ejection fraction. J Cardiol. 2012;59:344–51.

Chin JF, Aga YS, Abou Kamar S, Kroon D, Snelder SM, Van de Poll SWE, Kardys I, Brugts JJ, de Boer RA, van Dalen BM. Association between epicardial adipose tissue and cardiac dysfunction in subjects with severe obesity. Eur J Heart Fail. 2023;25:1936–43.

Choy M, Huang YW, Peng Y, Liang WH, He X, Chen C, Li JY, Zhu WE, Wei FF, Dong YG, et al. Association between epicardial adipose tissue and incident heart failure mediating by alteration of natriuretic peptide and myocardial strain. BMC Med. 2023;21.

Koepp KE, Obokata M, Reddy YNV, Olson TP, Borlaug BA. Hemodynamic and functional impact of epicardial Adipose tissue in heart failure with preserved ejection fraction. JACC Heart Fail. 2020;8:657–66.

Kardassis D, Bech-Hanssen O, Schönander M, Sjöström L, Petzold M, Karason K. Impact of body composition, fat distribution and sustained weight loss on cardiac function in obesity. Int J Cardiol. 2012;159:128–33.

Pugliese NR, Paneni F, Mazzola M, De Biase N, Del Punta L, Gargani L, Mengozzi A, Virdis A, Nesti L, Taddei S, et al. Impact of epicardial adipose tissue on cardiovascular haemodynamics, metabolic profile, and prognosis in heart failure. Eur J Heart Fail. 2021;23:1858–71.

Hardt F, Becker M, Brandenburg V, Grebe J, Dirrichs T, Gohmann RF, Fehrenbacher K, Schmoee J, Reinartz SD. Impact of epicardial adipose tissue volume upon left ventricular dysfunction in patients with mild-to-moderate aortic stenosis: a posthoc analysis. PLoS One. 2020;15.

Takahari K, Utsunomiya H, Itakura K, Yamamoto H, Nakano Y. Impact of the distribution of epicardial and visceral adipose tissue on left ventricular diastolic function. Heart Vessels. 2022;37:250–61.

Rhee TM, Kim HL, Lim WH, Seo JB, Kim SH, Zo JH, Kim MA. Association between epicardial adipose tissue thickness and parameters of target organ damage in patients undergoing coronary angiography. Hypertens Res. 2019;42:549–57.

Huynh K, Ayers C, Butler J, Neeland I, Kritchevsky S, Pandey A, Barton G, Berry JD. Association between thigh muscle fat infiltration and incident heart failure: the health ABC study. JACC Heart Fail. 2022;10:485–93.

Qu YL, Liu J, Li J, Shen SM, Chen XY, Tang HH, Yuan Y, Xia CC, Deng LP, Chen GY, et al. Association of abdominal adiposity, hepatic shear stiffness with subclinical left-ventricular remodeling evaluated by magnetic resonance in adults free of overt cardiovascular diseases: a prospective study. Cardiovasc Diabetol. 2023;22.

Yao F, Zeng LK, Hua ML, Zhang SQ, Liang JY, Gao Y, Chen C, Zhao XX, He AX, Liu M. Association of epicardial and visceral adipose tissue in relation to subclinical cardiac dysfunction in Chinese: Danyang study. BMJ Open. 2023;13.

Ma W, Zhang BW, Yang Y, Qi LT, Zhou J, Li M, Jia J, Zhang Y, Yong H. Association of epicardial fat thickness with left ventricular diastolic function parameters in a community population. BMC Cardiovasc Disord. 2021;21.

Tekin I, Edem E. Association of epicardial fat tissue with coronary artery disease and left ventricle diastolic function indicators. Med Sci Monit. 2018;24:6367–74.

Park HE, Choi SY, Kim M. Association of epicardial fat with left ventricular diastolic function in subjects with metabolic syndrome: assessment using 2-dimensional echocardiography. BMC Cardiovasc Disord. 2014;14.

Chu CY, Lee WH, Hsu PC, Lee MK, Lee HH, Chiu CA, Lin TH, Lee CS, Yen HW, Voon WC, et al. Association of increased epicardial adipose tissue thickness with adverse cardiovascular outcomes in patients with atrial fibrillation. Medicine. 2016;95.

Peng DD, Yu ZQ, Wang MW, Shi JP, Sun L, Zhang YY, Zhao WB, Chen C, Tang JK, Wang CY, et al. Association of metabolic dysfunction-associated fatty liver disease with left ventricular diastolic function and cardiac morphology. Front Endocrinol. 2022;13.

Chiu LS, Pedley A, Massaro JM, Benjamin EJ, Mitchell GF, McManus DD, Aragam J, Vasan RS, Cheng SS, Long MT. The association of non-alcoholic fatty liver disease and cardiac structure and function-Framingham Heart Study. Liver Int. 2020;40:2445–54.

Lai YH, Su CH, Hung TC, Yun CH, Tsai CT, Yeh HI, Hung CL. Association of non-alcoholic fatty liver disease and hepatic fibrosis with epicardial adipose tissue volume and atrial deformation mechanics in a large Asian population free from clinical heart failure. Diagnostics. 2022;12.

Lee YH, Kim KJ, Yoo ME, Kim G, Yoon HJ, Jo K, Youn JC, Yun M, Park JY, Shim CY, et al. Association of non-alcoholic steatohepatitis with subclinical myocardial dysfunction in non-cirrhotic patients. J Hepatol. 2018;68:764–72.

VanWagner LB, Wilcox JE, Colangelo LA, Lloyd-Jones DM, Carr JJ, Lima JA, Lewis CE, Rinella ME, Shah SJ. Association of nonalcoholic fatty liver disease with subclinical myocardial remodeling and dysfunction: a population-based study. Hepatology. 2015;62:773–83.

Min J, Putt ME, Yang W, Bertoni AG, Ding JZ, Lima JAC, Allison MA, Barr RG, Al-Naamani N, Patel RB, et al. Association of pericardial fat with cardiac structure, function, and mechanics: the multi-ethnic study of atherosclerosis. J Am Soc Echocardiogr. 2022;35:579.

Chiocchi M, Cavallo AU, Pugliese L, Cesareni M, Pasquali D, Accardo G, De Stasio V, Spiritigliozzi L, Benelli L, D’Errico F, et al. Cardiac computed tomography evaluation of association of left ventricle disfunction and epicardial adipose tissue density in patients with low to intermediate cardiovascular risk. Medicina-Lithuania. 2023;59.

Kostka F, Ittermann T, Gross S, Laqua FC, Bülow R, Völzke H, Dörr M, Kühn JP, Markus MRP, Kromrey ML. Cardiac remodelling in non-alcoholic fatty liver disease in the general population. Liver Int. 2024;44:1032–41.

Hearon CM, Reddy S, Dias KA, Shankar A, MacNamara J, Levine B, Sarma S. Characterizing regional and global effects of epicardial adipose tissue on cardiac systolic and diastolic function. Obesity. 2023;31:1884–93.

Yoon HE, Choi SS, Kim Y, Shin SJ. The clinical usefulness of measurement of visceral fat area using multi-frequency bioimpedance: the association with cardiac and renal function in general population with relatively normal renal function. Int J Med Sci. 2017;14:1375–81.

Çetin M, Kocaman SA, Durakoglugil ME, Erdogan T, Ergül E, Dogan S, Çanga A. Effect of epicardial adipose tissue on diastolic functions and left atrial dimension in untreated hypertensive patients with normal systolic function. J Cardiol. 2013;61:359–64.

Topuz M, Dogan A. The effect of epicardial adipose tissue thickness on left ventricular diastolic functions in patients with normal coronary arteries. Kardiologia Polska. 2017;75:196–203.

Huang S, Shi K, Li Y, Wang J, Jiang L, Gao Y, Yan WF, Shen LT, Yang ZG. Effect of metabolic dysfunction-associated fatty liver disease on left ventricular deformation and atrioventricular coupling in patients with metabolic syndrome assessed by MRI. J Magn Reson Imaging. 2023;58:1098–107.

Shao JW, Chen BH, Kamil AS, Baiyasi A, Wu LM, Ma J. Epicardial adipose tissue in obesity with heart failure with preserved ejection fraction: cardiovascular magnetic resonance biomarker study. World J Cardiol. 2024;16:149–60.

Kim SA, Kim MN, Shim WJ, Park SM. Epicardial adipose tissue is related to cardiac function in elderly women, but not in men. Nutr Metab Cardiovasc Dis. 2017;27:41–7.

Jin XY, Hung CL, Tay WT, Soon D, Sim D, Sung KT, Loh SY, Lee S, Jaufeerally F, Ling LH, et al. Epicardial adipose tissue related to left atrial and ventricular function in heart failure with preserved versus reduced and mildly reduced ejection fraction. Eur J Heart Fail. 2022;24:1346–56.

Lin JL, Sung KT, Lai YH, Yen CH, Yun CH, Su CH, Kuo JY, Liu CY, Chien CY, Cury RC, et al. Epicardial adiposity in relation to metabolic abnormality, circulating adipocyte FABP, and preserved ejection fraction heart failure. Diagnostics. 2021;11.

Mahabadi AA, Anapliotis V, Dykun I, Hendricks S, Al-Rashid F, Luedike P, Totzeck M, Rassaf T. Epicardial fat and incident heart failure with preserved ejection fraction in with disease. Int J Cardiol. 2022;357:140–5.

Dabbah S, Komarov H, Marmor A, Assy N. Epicardial fat, rather than pericardial fat, is independently associated with diastolic filling in subjects without apparent heart disease. Nutr Metab Cardiovasc Dis. 2014;24:877–82.

Vural M, Talu A, Sahin D, Elalmis OU, Durmaz HA, Uyanık S, Dolek BA. Evaluation of the relationship between epicardial fat volume and left ventricular diastolic dysfunction. Jpn J Radiol. 2014;32:331–9.

Ates K, Demir M. Importance of epicardial adipose tissue as a predictor of heart failure with preserved ejection fraction. Rev Assoc Med Bras. 2022;68:1178–84.

van Woerden G, van Veldhuisen DJ, Gorter TM, van Empel VPM, Hemels MEW, Hazebroek EJ, van Veldhuisen SL, Willems TP, Rienstra M, Westenbrink BD. Importance of epicardial adipose tissue localization using cardiac magnetic resonance imaging in patients with heart failure with mid-range and preserved ejection fraction. Clin Cardiol. 2021;44:987–93.

Turak O, Özcan F, Canpolat U, Isleyen A, Cebeci M, Öksüz F, Mendi MA, Çagli K, Gölbasi Z, Aydogdu S. Increased echocardiographic epicardial fat thickness and high-sensitivity CRP level indicate diastolic dysfunction in patients with newly diagnosed essential hypertension. Blood Press Monit. 2013;18:259–64.

Coelho P, Duarte H, Alcafache C, Rodrigues F. The influence of pericardial fat on left ventricular diastolic function. Diagnostics. 2024;14:702.

Hua N, Chen ZJ, Phinikaridou A, Pham T, Qiao Y, LaValley MP, Bigornia SJ, Ruth MR, Apovian CM, Ruberg FL, Hamilton JA. The influence of pericardial fat upon left ventricular function in obese females: evidence of a site-specific effect. J Cardiovasc Magn Reson. 2014;16.

Sawada N, Nakanishi K, Daimon M, Yoshida Y, Ishiwata J, Hirokawa M, Nakao T, Morita H, Di Tullio MR, Homma S, Komuro I. Influence of visceral adiposity accumulation on adverse left and right ventricular mechanics in the community. Eur J Prev Cardiol. 2020;27:2006–15.

Kosmala W, Jedrzejuk D, Derzhko R, Przewlocka-Kosmala M, Mysiak A, Bednarek-Tupikowska G. Left ventricular function impairment in patients with normal-weight obesity contribution of abdominal fat deposition, profibrotic state, reduced insulin sensitivity, and proinflammatory activation. Circulation-Cardiovasc Imaging. 2012;5:349–56.

Nakanishi K, Fukuda S, Tanaka A, Otsuka K, Taguchi H, Shimada K. LERelationships between periventricular epicardial adipose tissue accumulation, coronary microcirculation, and left ventricular diastolic dysfunction. Can J Cardiol. 2017;33:1489–97.

Zhou H, An DA, Ni ZH, Xu JR, Zhou Y, Fang W, Lu RH, Ying L, Huang JY, Yao QY, et al. Magnetic resonance imaging quantification of accumulation of epicardial adipose tissue adds independent risks for diastolic dysfunction among dialysis patients. J Magn Reson Imaging. 2022;56:1184–94.

Wu CK, Lee JK, Hsu JC, Su MM, Wu YF, Lin TT, Lan CW, Hwang JJ, Lin LY. Myocardial adipose deposition and the development of heart failure with preserved ejection fraction. Eur J Heart Fail. 2020;22:445–54.

Chung GE, Lee JH, Lee H, Kim MK, Yim JY, Choi SY, Kim YJ, Yoon JH, Kim D. Nonalcoholic fatty liver disease and advanced fibrosis are associated with left ventricular diastolic dysfunction. Atherosclerosis. 2018;272:137–44.

Mantovani A, Pernigo M, Bergamini C, Bonapace S, Lipari P, Pichiri I, Bertolini L, Valbusa F, Barbieri E, Zoppini G et al. Nonalcoholic fatty liver disease is independently associated with early left ventricular diastolic dysfunction in patients with type 2 diabetes. PLoS One. 2015;10.

Wang QQ, Ma WY, Xia JZ. Nonalcoholic fatty liver is associated with further left ventricular abnormalities in patients with type 2 diabetes mellitus: a 3-dimensional speckle-tracking study. J Ultrasound Med. 2018;37:1899–911.

Simon TG, Bamira DG, Chung RT, Weiner RB, Corey KE. Nonalcoholic steatohepatitis is associated with cardiac remodeling and dysfunction. Obesity. 2017;25:1313–6.

Kenchaiah S, Ding J, Carr JJ, Allison MA, Budoff MJ, Tracy RP, Burke GL, McClelland RL, Arai AE, Bluemke DA. Pericardial fat and the risk of heart failure. J Am Coll Cardiol. 2021;77:2638–52.

Wolf P, Winhofer Y, Smajis S, Jankovic D, Anderwald CH, Trattnig S, Luger A, Krebs M, Krssák M. Pericardial- rather than intramyocardial fat is independently associated with left ventricular systolic heart function in metabolically healthy humans. PLoS One. 2016;11.

Haykowsky MJ, Nicklas BJ, Brubaker PH, Hundley WG, Brinkley TE, Upadhya B, Becton JT, Nelson MD, Chen HY, Kitzman DW. Regional adipose distribution and its relationship to exercise intolerance in older obese patients who have heart failure with preserved ejection fraction. JACC Heart Fail. 2018;6:640–9.

Rao VN, Bush CG, Mongraw-Chaffin M, Hall ME, Clark D, Fudim M, Correa A, Hammill BG, O’Brien E, Min YI, Mentz RJ. Regional adiposity and risk of heart failure and mortality: the Jackson Heart Study. J Am Heart Assoc. 2021;10.

Neeland IJ, Gupta S, Ayers CR, Turer AT, Rame JE, Das SR, Berry JD, Khera A, McGuire DK, Vega GL, et al. Relation of regional fat distribution to left ventricular structure and function. Circulation-Cardiovasc Imaging. 2013;6:800–7.

Zhu J, Li WJ, Xie Z, Zhuo KM. Relationship between epicardial adipose tissue and biventricular longitudinal strain and strain rate in patients with type 2 diabetes mellitus. Acad Radiol. 2023;30:833–40.

Canepa M, Strait JB, Milaneschi Y, AlGhatrif M, Ramachandran R, Makrogiannis S, Moni M, David M, Brunelli C, Lakatta EG, Ferrucci L. The relationship between visceral adiposity and left ventricular diastolic function: results from the Baltimore longitudinal study of aging. Nutr Metab Cardiovasc Dis. 2013;23:1263–70.

Sawada N, Daimon M, Kawata T, Nakao T, Kimura K, Nakanishi K, Kurano M, Hirokawa M, Xu BQ, Yamanaka Y, et al. The significance of the effect of visceral adiposity on left ventricular diastolic function in the general population. Sci Rep. 2019;9.

Ying W, Sharma K, Yanek LR, Vaidya D, Schär M, Markl M, Subramanya V, Soleimani S, Ouyang P, Michos ED, et al. Visceral adiposity, muscle composition, and exercise tolerance in heart failure with preserved ejection fraction. Esc Heart Fail. 2021;8:2535–45.

Tipton E. Robust variance estimation in meta-regression with binary dependent effects. Res Synth Methods. 2013;4:169–87.

Antonopoulos AS, Papastamos C, Cokkinos DV, Tsioufis K, Tousoulis D. Epicardial adipose tissue in myocardial disease: from physiology to heart failure phenotypes. Curr Probl Cardiol. 2023;48:101841.

Ong FJ, Ahmed BA, Oreskovich SM, Blondin DP, Haq T, Konyer NB, Noseworthy MD, Haman F, Carpentier AC, Morrison KM, Steinberg GR. Recent advances in the detection of brown adipose tissue in adult humans: a review. Clin Sci (Lond). 2018;132:1039–54.

Peterson SJ, Foley S. Clinician’s guide to understanding effect size, alpha level, power, and sample size. Nutr Clin Pract. 2021;36:598–605.

Wang R, Lagakos SW, Ware JH, Hunter DJ, Drazen JM. Statistics in medicine — reporting of subgroup analyses in clinical trials. N Engl J Med. 2007;357:2189–94.

Tsujimoto T, Kajio H. Abdominal obesity is associated with an increased risk of all-cause mortality in patients with HFpEF. J Am Coll Cardiol. 2017;70:2739–49.

Oikonomou EK, Antoniades C. The role of adipose tissue in cardiovascular health and disease. Nat Rev Cardiol. 2019;16:83–99.

Tilg H, Moschen AR. Adipocytokines: mediators linking adipose tissue, inflammation and immunity. Nat Rev Immunol. 2006;6:772–83.

Wang QA, Tao C, Gupta RK, Scherer PE. Tracking adipogenesis during white adipose tissue development, expansion and regeneration. Nat Med. 2013;19:1338–44.

Scheele C, Wolfrum C. Brown adipose crosstalk in tissue plasticity and human metabolism. Endocr Rev. 2020;41:53–65.

Kwok KH, Lam KS, Xu A. Heterogeneity of white adipose tissue: molecular basis and clinical implications. Exp Mol Med. 2016;48:e215.

Wu Y, Zhang A, Hamilton DJ, Deng T. Epicardial fat in the maintenance of cardiovascular health. Methodist Debakey Cardiovasc J. 2017;13:20–4.

Ansaldo AM, Montecucco F, Sahebkar A, Dallegri F, Carbone F. Epicardial adipose tissue and cardiovascular diseases. Int J Cardiol. 2019;278:254–60.

Borlaug BA, Reddy YNV. The role of the pericardium in heart failure: implications for pathophysiology and treatment. JACC Heart Fail. 2019;7:574–85.

Gaborit B, Venteclef N, Ancel P, Pelloux V, Gariboldi V, Leprince P, Amour J, Hatem SN, Jouve E, Dutour A, Clément K. Human epicardial adipose tissue has a specific transcriptomic signature depending on its anatomical peri-atrial, peri-ventricular, or peri-coronary location. Cardiovasc Res. 2015;108:62–73.

He S, Zhu H, Zhang J, Wu X, Zhao L, Yang X. Proteomic analysis of epicardial adipose tissue from heart disease patients with concomitant heart failure with preserved ejection fraction. Int J Cardiol. 2022;362:118–25.

Pou KM, Massaro JM, Hoffmann U, Vasan RS, Maurovich-Horvat P, Larson MG, Keaney JF Jr, Meigs JB, Lipinska I, Kathiresan S, et al. Visceral and subcutaneous adipose tissue volumes are cross-sectionally related to markers of inflammation and oxidative stress: the Framingham Heart Study. Circulation. 2007;116:1234–41.

Britton KA, Massaro JM, Murabito JM, Kreger BE, Hoffmann U, Fox CS. Body fat distribution, incident cardiovascular disease, cancer, and all-cause mortality. J Am Coll Cardiol. 2013;62:921–5.

Mahabadi AA, Massaro JM, Rosito GA, Levy D, Murabito JM, Wolf PA, O’Donnell CJ, Fox CS, Hoffmann U. Association of pericardial fat, intrathoracic fat, and visceral abdominal fat with cardiovascular disease burden: the Framingham Heart Study. Eur Heart J. 2009;30:850–6.

Kranendonk ME, van Herwaarden JA, Stupkova T, de Jager W, Vink A, Moll FL, Kalkhoven E, Visseren FL. Inflammatory characteristics of distinct abdominal adipose tissue depots relate differently to metabolic risk factors for cardiovascular disease: distinct fat depots and vascular risk factors. Atherosclerosis. 2015;239:419–27.

Download references

Acknowledgements

I would like to thank Dr Qian from Peking University for his kind support.

Scientific and technological innovation project of China Academy of Chinese Medical Sciences (C12021A01603) and Clinical Research Center Construction Project of Guang’anmen Hospital, CACMS (2022LYJSZX26).

Author information

Zhenyue Fu, Yajiao Wang, and Yuxin Wang are co-first authors.

Authors and Affiliations

Department of General Internal Medicine, Guang’anmen Hospital, China Academy of Chinese Medical Sciences, Beijing, China

Zhenyue Fu, Yajiao Wang, Yuxin Wang, Shuqing Shi, Yumeng Li, Bingxuan Zhang & Qingqiao Song

Beijing University of Chinese Medicine, Beijing, China

Department of Cardiovascular, Guang’anmen Hospital, China Academy of Chinese Medical Sciences, Beijing, China

You can also search for this author in PubMed   Google Scholar

Contributions

Study design and writing the review were done by Zhenyue Fu and Yajiao Wang; the literature search was done by Shuqing Shi and Yumeng Li; Bingxuan Zhang were responsible for data calculation, Zhenyue Fu and Yuxin Wang were responsible for translation, and HuaqinWu and Qingqiao Song did the secondary revision of the literature.

Corresponding author

Correspondence to Qingqiao Song .

Ethics declarations

Ethics approval and consent to participate.

Not applicable.

Consent for publication

Competing interests.

The authors declare no competing interests.

Additional information

Publisher’s note.

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary Information

Supplementary material 1., rights and permissions.

Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc-nd/4.0/ .

Reprints and permissions

About this article

Cite this article.

Fu, Z., Wang, Y., Wang, Y. et al. Linking abnormal fat distribution with HFpEF and diastolic dysfunction: a systematic review, meta-analysis, and meta-regression of observational studies. Lipids Health Dis 23 , 277 (2024). https://doi.org/10.1186/s12944-024-02266-y

Download citation

Received : 20 June 2024

Accepted : 19 August 2024

Published : 31 August 2024

DOI : https://doi.org/10.1186/s12944-024-02266-y

Share this article

Anyone you share the following link with will be able to read this content:

Sorry, a shareable link is not currently available for this article.

Provided by the Springer Nature SharedIt content-sharing initiative

• Abnormal fat
• Cardiac diastolic dysfunction
• Heart failure with preserved ejection fraction
• Systematic review
• Meta-analysis

Lipids in Health and Disease

ISSN: 1476-511X

• General enquiries: [email protected]