A systematic review is just one type of evidence synthesis. It differentiates itself from these others in that it appraises the quality of included studies, provides a synthesis and often a meta-analysis of the literature, takes great pains to mitigate bias, and follows certain reporting standards and protocols. While systematic reviews are comprehensive and one of the most rigorous forms of evidence synthesis, they may not always be the best fit for your research.
Other evidence synthesis methods include, but are not limited to:
Literature (Narrative) Review
- A broad term referring to reviews with a wide scope and non-standardized methodology.
- Search strategies, comprehensiveness, and time range covered will vary and do not follow an established protocol.
- Explains how one piece of literature fits in amongst others on the same research question.
Scoping Review
- Collection and categorization of existing evidence in order to assess the size and scope of available literature on a broad research question. It does not attempt to synthesize the results in a comprehensive manner.
- Seeks to identify research gaps and opportunities for evidence synthesis rather than searching for the effect of an intervention.
Systematic Review
- Systematically and transparently collect and categorize existing evidence on a broad question of scientific, policy or management importance.
- Compares, evaluates, and synthesizes evidence in a search for the effect of an intervention.
- Time-intensive and often take months to a year or more to complete.
- The most commonly referred to type of evidence synthesis. Sometimes confused as a blanket term for other types of reviews.
Umbrella Review
- Reviews other systematic reviews on a topic.
- Often defines a broader question than is typical of a traditional systematic review.
- Most useful when there are competing interventions to consider.
Meta-analysis
- Statistical technique for combining the findings from disparate quantitative studies.
- Uses statistical methods to objectively evaluate, synthesize, and summarize results.
- May be conducted independently or as part of a systematic review.
- All meta-analyses should be part of a systematic review, but not all systematic reviews will include a meta-analysis.
Rapid Review
- Applies Systematic Review methodology within a time-constrained setting.
- Employs methodological "shortcuts" (limiting search terms for example) at the risk of introducing bias.
- Useful for addressing issues needing quick decisions, such as developing policy recommendations.
- See Evidence Summaries: The Evolution of a Rapid Review Approach
Adapted from:
Grant, M.J., & Booth, A. (2009). A typology of reviews: An analysis of 14 review types and associated methodologies. Health Information &
Libraries Journal, 26, 91–108.
Khangura, S., Konnyu, K., Cushman, R., Grimshaw, J., & Moher, D. (2012). Evidence summaries: The evolution of a rapid review approach. Systematic Reviews, 1(1), 10-10
Samnani, S. S., Vaska, M., Ahmed, S., & Turin, T. C. (2017). Review typology: The basic types of reviews for synthesizing evidence for the purpose of knowledge translation. Journal of the College of Physicians and Surgeons--Pakistan, 27(10), 635-641
