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Systematic Reviews in the Health Sciences

A guide to systematic reviews in the health sciences.

Defining Systematic Reviews

“A systematic review attempts to collate all the empirical evidence that fits pre-specified eligibility criteria in order to answer a specific research question. It uses explicit, systematic methods that are selected with a view to minimizing bias, thus providing more reliable findings from which conclusions can be drawn and decisions made (Antman et al 1992, Oxman and Guyatt 1993).”

Chapter 1: Starting a review. In: Higgins JPT, Thomas J, Chandler J, Cumpston M, Li T, Page MJ, Welch VA (editors). Cochrane Handbook for Systematic Reviews of Interventions version 6.2 (updated February 2021). Cochrane, 2021. Available from www.training.cochrane.org/handbook.

To put this in other words, a systematic review:

  • Seeks to answer a narrowly focused research question
  • Involves a comprehensive literature search to identify all studies that meet eligibility criteria
  • Uses explicit, systematic, and reproducible methods to minimize bias
  • Critically appraises and synthesizes included studies
  • May use statistical methods to analyze and summarize the results in a meta-analysis

A systematic review is a study of studies and it follows a prescribed research methodology.

There are other review types that do this, but do not follow the exact process of a systematic review. These are listed in the table below with further resources. 

Scoping Review Rapid Review Narrative Review
  • Assesses the size and scope of available research literature in order to identify gaps and research needs
  • The extent of the literature search depends on the reviewers’ time and resource constraints
  • Quality of existing evidence may be described but the review does not usually include a formal quality appraisal
  • Uses methods of systematic reviewing in a shorter time frame for an immediate answer to an urgent or emerging topic
  • Supports policy decisions
  • Takes three weeks to six months
  • Focuses on more easily retrievable evidence
  • Summary of research that covers a wide area
  • Lacks explicit descriptions of systematic methods
  • May not have complete evidence
  • Relevance and validity of studies not necessarily discussed
  • Cannot be easily replicated

For More Information on Reviews, consider the following: 

  • Sutton A, Clowes M, Preston L, Booth A. Meeting the review family: exploring review types and associated information retrieval requirements. Health Information & Libraries Journal. 2019 Sep;36(3):202-222. https://doi.org/10.1111/hir.12276

  • Munn Z, Peters MDJ, Stern C, Tufanaru C, McArthur A, Aromataris E. Systematic review or scoping review? Guidance for authors when choosing between a systematic or scoping review approach. BMC Medical Research Methodology. 2018 Nov 19;18(1):143. https://doi.org/10.1186/s12874-018-0611-x

  • What Review is Right for You? Quiz-Based Decision Tool

Systematic Review Standards

There are a variety of organizations that help inform evidence-based decision making, specifically in the area of systematic reviews. The Cochrane Collaboration is one of the best known in medicine, but there are others as well, including:

There are several guide books for conducting systematic reviews. Two of the ones we refer to most often are the Cochrane Handbook for Systematic Reviews of Interventions, and Finding What Works in Health Care: Standards for Systematic Reviews. The Cochrane Handbook is quite a thick volume, so you might want to go to Finding What Works in Health Care if you’re looking for something more manageable (it’s about 230 pages, not including appendices). That being said, Cochrane is the gold standard.

For an online guide, the Centre for Reviews and Dissemination at the University of York has an online guide called Systematic Reviews: CRD's guidance for undertaking reviews in health care