Basics of Systematic Reviews

A guide to evidence synthesis

Types of Reviews

Literature Review (Narrative Review)

Collects key sources on a topic and discusses those sources in conversation with each other

  • Standard for research articles in most disciplines
  • Tells the reader what is known, or not known, about a particular issue, topic, or subject
  • Demonstrates knowledge and understanding of a topic
  • Establishes context or background for a case or argument
  • Helps develop the author’s ideas and perspective

Rapid Review

Thorough methodology but with process limitations in place to expedite the completion of a review.

  • For questions that require timely answers
  • 3-4 months vs. 12-24 months
  • Limitations - scope, comprehensiveness bias, and quality of appraisal
  • Discusses potential effects that the limited methods may have had on results

Scoping Review

Determine the scope or coverage of a body of literature on a given topic and give clear indication of the volume of literature and studies available as well as an overview of its focus.

  • Identify types of available evidence in a given field
  • Clarify key concepts/definitions in the literature
  • Examine how research is conducted on a certain topic or field
  • Identify key factors related to a concept
  • Precursor to a systematic review
    • Key difference is focus
  • Identify and analyze knowledge gaps

Systematic Review

Attempts to identify, appraise, and summarize all empirical evidence that fits pre-specified eligibility criteria to answer a specific research question.

  • clearly defined question with inclusion/exclusion criteria
  • rigorous and systematic search of the literature
  • thorough screening of results
  • data extraction and management
  • analysis and interpretation of results
  • risk of bias assessment of included studies

Meta-Analysis

Used to systematically synthesize or merge the findings of single, independent studies, using statistical methods to calculate an overall or ‘absolute’ effect.

  • Combines results from multiple empirical studies
  • Requires systematic review first
  • Use well recognized, systematic methods to account for differences in sample size, variability (heterogeneity) in study approach and findings (treatment effects)
  • Test how sensitive their results are to their own systematic review protocol

Umbrella Reviews

This type of review is conducted to compile, synthesize, and assess the quality of systematic reviews and meta-analyses.  I could be described as a "review of reviews". The process for undertaking an umbrella review is similar to systematic reviews.  

  • Useful when there are many systematic reviews that exist on a particular topic or question.
  • Conducted to synthesize the highest levels of evidence available for a given topic.
  • Should only be undertaken if the selected intervention of interest has already been discussed in reviews.

For information on these and additional types of reviews, please see the below articles: