Abstract
Systematic reviews involve the application of scientific methods to reduce bias in review of literature. The key components of a systematic review are a well-defined research question, comprehensive literature search to identify all studies that potentially address the question, systematic assembly of the studies that answer the question, critical appraisal of the methodological quality of the included studies, data extraction and analysis (with and without statistics), and considerations towards applicability of the evidence generated in a systematic review. These key features can be remembered as six ‘A’; Ask, Access, Assimilate, Appraise, Analyze and Apply. Meta-analysis is a statistical tool that provides pooled estimates of effect from the data extracted from individual studies in the systematic review. The graphical output of meta-analysis is a forest plot which provides information on individual studies and the pooled effect. Systematic reviews of literature can be undertaken for all types of questions, and all types of study designs. This article highlights the key features of systematic reviews, and is designed to help readers understand and interpret them. It can also help to serve as a beginner’s guide for both users and producers of systematic reviews and to appreciate some of the methodological issues.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
References
Sackett D, Strauss S, Richardson W, et al. Evidence-Based Medicine: How to practice and teach EBM. 2nd ed. Churchill Livingstone: 2000.
Cook DJ, Mulrow CD, Haynes RB. Systematic reviews: Synthesis of best evidence for clinical decisions. Ann Intern Med. 1997;126:376–80.
PennState Eberley College of Science. Lesson 4: Bias and Random Error. Accessed October 01, 2020. Available from: https://online.stat.psu.edu/stat509/node/26/
Comprehensive Meta-analysis. Accessed October 01, 2020. Available from: https://www.meta-analysis.com/pages/why_do.php?cart=
National Institute for Health Research. PROSPERO International prospective register of systematic reviews. Accessed October 01, 2020. Available from: https://utas.libguides.com/SystematicReviews/Protocol
Mathew JL, Singh M. Evidence based child health: Fly but with feet on the ground! Indian Pediatr. 2008;45:95–8.
Virginia Commonwealth University. How to conduct a literature review (Health Sciences). Accessed October 01, 2020. Available from: https://guides.library.vcu.edu/health-sciences-lit-review/question
http://www.knowledge.scot.nhs.uk/k2atoolkit/source/identify-what-you-need-to-know/spice.aspx
Cooke A., Smith D, Booth A. Beyond PICO: The SPIDER tool for qualitative evidence synthesis. Qualitative Health Research. 2012;22:1435–43.
Booth A, Noyes J, Flemming K, et al. Formulating questions to explore complex interventions within quali-tative evidence synthesis. Accessed October 01, 2020. Available from: https://library.nd.edu.au/evidencebasedpractice/ask/question
Infolibrarian. Bibliographic databases. Accessed October 01, 2020. Available from: http://infolibrarian.com/edb.html
E-Resources for China Studies. Accessed October 01, 2020. Available from: http://www.wanfangdata.com
LILACS, health information from Latin America and the Caribbean countries. Accessed October 01, 2020. Available from: https://lilacs.bvsalud.org/en/
OpenGrey. System for information on grey literature in Europe. Accessed October 01, 2020. Available from: http://www.opengrey.eu
Sterne JAC, Savoviæ J, Page MJ, et al. RoB 2: A revised tool for assessing risk of bias in randomised trials. BMJ. 2019;366:14898.
Cochrane Training. RevMan 5. Accessed October 01, 2020. Available from: https://training.cochrane.org/online-learning/core-software-cochrane-reviews/revman/revman-5-download.
Wells GA, Shea B, O’Connell D, et al. The Newcastle-Ottawa Scale (NOS) for assessing the quality of non-randomised studies in meta-analyses. Accessed October 02, 2020. Available from: http://www.ohri.ca/programs/clinical-epidemiology/oxford.asp
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.
Sterne JA, Hernan MA, Reeves BC, et al. ROBINS-I: A tool for assessing risk of bias in non-randomised studies of interventions BMJ. 2016;355:i4919.
University of Bristol. QUADAS-2. Accessed October 01, 2020. Available from: https://www.bristol.ac.uk/population-health-sciences/projects/quadas/quadas-2/
OHAT Risk of Bias Rating Tool for Human and Animal Studies. Accessed February 27, 2021. Available from: https://ntp.niehs.nih.gov/ntp/ohat/pubs/riskofbiastool_508.pdf
Hooijmans CR, Rovers MM, De Vries RB, et al. SYRCLE’s risk of bias tool for animal studies. BMC Med Res Meth. 2014;14:1–9.
Cochrane Methods. About IPD meta-analyses. Accessed October 01, 2020. Available from: https://methods.cochrane.org/ipdma/about-ipd-meta-analyses
Borenstein M, Hedges L, Rothstein H. Meta-analysis. Fixed effect vs. random effects. Accessed October 01, 2020. Available from: https://www.meta-analysis.com/downloads/M-a_f_ejv_r_e_sv.pdf
Heterogeneity in Meta-analysis. Accessed October 01, 2020. Available from: https://www.statsdirect.com/help/meta_analysis/heterogeneity.htm
Dalton JE, Bolen SD, Mascha EJ. Publication bias: The elephant in the review. Anesth Analg. 2016;123:812–3.
Begg CB, Mazumdar M. Operating characteristics of a rank correlation test for publication bias. Biometrics. 1994; 50:1088–101.
Egger M, Smith GD, Schneider M, et al. Bias in meta-analysis detected by a simple, graphical test. BMJ. 1997;315:629–34.
Duval S, Tweedie R. Trim and fill: A simple funnel-plot—based method of testing and adjusting for publication bias in metaanalysis. Biometrics. 2000;56:455–63.
Rosenthal R. The file drawer problem and tolerance for null results. Psycholog Bulletin. 1979;86:638–41.
Schünemann HJ, Higgins JPT, Vist GE, et al. Chapter 14: Completing ‘Summary of findings’ tables and grading the certainty of the evidence. Accessed October 01, 2020. Available from: www.training.coachrane.org/handbook/current/chapter-14
Drucker AM, Fleming P, Chan AW. Research techniques made simple: Assessing risk of bias in systematic reviews. J Invest Dermatol. 2016;136:e109–e14.
Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA). Accessed October 01, 2020. Available from: http://www.prisma-statement.org
Moher D, Liberati A, Tetzlaff J, Altman DG, The PRISMA Group. Preferred Reporting Items for Systematic reviews and Meta-Analyses: The PRISMA Statement. PLoS Med. 2009;6:e1000097.
Critical Appraisal Skills Programme. 10 questions to help you make sense of a Systematic review. Accessed October 01, 2020. Available from: https://casp-uk.net/wp-content/uploads/2018/01/CASP-Systematic-Review-Checklist_ 2018.pdf
Author information
Authors and Affiliations
Corresponding author
Additional information
Note
Additional material related to this paper is available with the online version at www.indianpediatrics.net
Rights and permissions
About this article
Cite this article
Mathew, J.L. Systematic Reviews and Meta-Analysis: A Guide for Beginners. Indian Pediatr 59, 320–330 (2022). https://doi.org/10.1007/s13312-022-2500-y
Published:
Issue Date:
DOI: https://doi.org/10.1007/s13312-022-2500-y