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Systematic Review Guide

The left column displays the Table of Contents. Depending on your familiarity, you can either methodically review the Guide in its entirety or go directly to one (or more) specific chapter(s) for a quick review.

The tabs along the top within each chapter include more material and are organized to help users find information efficiently.

Example of introduction

A systematic review is:

A scientific investigation that focuses on a specific question and that uses explicit, planned scientific methods to identify, select, assess, and summarize the findings of similar but separate studies. It may or may not include a quantitative synthesis of the results from separate studies (meta-analysis) depending on the available data.

IOM (Institute of Medicine), 2011

The following video prepared by the Cochrane Consumers and Communication Group provides a brief overview of systematic reviews.

Well-conducted systematic reviews systematically identify, select, assess, and synthesize the relevant body of research, and will help make clear what is known and not known about the potential benefits and harms of alternative drugs, devices, and other healthcare services. Thus, systematic reviews of comparative effectiveness research (CER) can be essential for clinicians who strive to integrate research findings into their daily practices, for patients to make well-informed choices about their own care, for professional medical societies and other organizations that develop clinical practice guidelines (CPGs), and for payers and policy makers. Systematic reviews can also inform medical coverage decisions and be used to set agendas and funding for primary research by highlighting gaps in evidence.

IOM (Institute of Medicine), 2011)

Not every review is a systematic review (SR). It is important to use the review type that best matches the purpose, scope, and time constraints of the project. For more information on different review types, see Types of Reviews.

Before you get started, ask yourself the following questions:

  1. Is there a need for a new review? It is important to make sure that the proposed systematic review is addressing novel issues, and not duplicating existing systematic reviews or other ongoing reviews. (IOM (Institute of Medicine), 2011)
  2. Do you have a specific and clearly defined question? A focused research question is critical – it determines other components of the review, including the search strategy for studies, data extraction, synthesis, and presentation of findings. Well-formulated systematic review questions often use a structured format to improve the scientific rigor, such as the PICO(M) mnemonic: population, intervention, comparison, outcomes, methodology. Don't be surprised if it takes time to finalize the research question – it is time well spent. (IOM (Institute of Medicine), 2011)
  3. Do you have a team to work on the systematic review? The systematic review team should be multidisciplinary, capable of defining the clinical question and proficient in performing the technical aspects of the review:

    • Develop systematic review protocol
    • Design search strategies to retrieve potentially relevant articles
    • Select studies based on explicit inclusion and exclusion criteria
    • Critically appraise the included studies
    • Perform data analysis and interpret the results

    Members include subject experts, reviewers, librarian, and statistician. Minimizing conflict of interest and bias are critical to credibility and scientific rigor. (IOM (Institute of Medicine), 2011)

  4. Do you have the time that it takes to properly conduct a systematic review? Planning and conducting a systematic review is a time-intensive research project. Time to completion will vary depending on the scope of the review and the size and availability of the review team. A well-designed systematic review may take a year or more to complete.(Higgins JPT, 2020 (updated September 2020))

    Green S, Higgins JPT (editors). Chapter 2: Preparing a Cochrane review in Cochrane Handbook for Systematic Reviews of Interventions Version 5.1.0 (updated March 2011).
    Note: the timeline has been archived.
  5. Can you meet all of the requirements for a systematic review as outlined in the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) checklist? Developed by a group of 29 review authors, methodologists, clinicians, medical editors and consumers, the checklist encompasses 27 items deemed essential for transparent reporting of a systematic review.

The questions are adapted from the Institute of Medicine's Finding What Works in Health Care: Standards for Systematic Reviews, Cochrane Handbook for Systematic Reviews of Interventions and PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses).

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