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Evidence Synthesis : Types of Reviews

Useful resources and tools for planning and conducting systematic reviews

Quick look at review types

Image of review types in columns. Across the top it reads Speed Methodological detail, risk of bias, comprehensiveness. From top to bottom the row labels read Narrative review, critically appraised topic (CAT), scoping review, rapid review, systematic review with or without meta analysis

Brennan, M. L., Arlt, S. P., Belshaw, Z., Buckley, L., Corah, L., Doit, H., Fajt, V. R., Grindlay, D., Moberly, H. K., Morrow, L. D., Stavisky, J., & White, C. (2020). Critically Appraised Topics (CATs) in Veterinary Medicine: Applying Evidence in Clinical Practice. Frontiers in veterinary science, 7, 314. https://doi.org/10.3389/fvets.2020.00314

Types of Reviews

Is a systematic review right for your research? There are many different types of reviews, a systematic review is one of many to choose from. 

Type of Review Description Search Appraisal Synthesis Analysis
Literature/Narrative Review Generic term: published materials that provide examination of recent or current literature. Can cover wide range of subjects at various levels of completeness and comprehensiveness. May include research findings. May or may not include comprehensive searching. May or may not include quality assessment. Typically narrative. Analysis may be chronological, conceptual, thematic, etc.
Rapid Review Assessment of what is already known about a policy or practice issue, by using systematic review methods to search and critically appraise existing research. Completeness of searching determined by time constraints. Time-limited formal quality assessment. Typically narrative and tabular. Quantities of literature and overall quality/direction of effect of literature.
Scoping Review Preliminary assessment of potential size and scope of available research literature. Aims to identify nature and extent of research evidence (usually including ongoing research). Completeness of searching determined by time/scope constraints. May include research in progress. No formal quality assessment. Typically tabular with some narrative commentary. Characterizes quantity and quality of literature, perhaps by study design and other key features. Attempts to specify a viable review.
Systematic Review Seeks to systematically search for, appraise and synthesis research evidence, often adhering to guidelines on the conduct of a review. Aims for exhaustive, comprehensive searching. Quality assessment may determine inclusion/exclusion. Typically narrative with tabular accompaniment. What is known; recommendations for practice. What remains unknown; uncertainty around findings, recommendations for future research.
Meta-Analysis  Technique that statistically combines the results of quantitative studies to provide a more precise effect of the results. Aims for exhaustive searching. May use funnel plot to assess completeness. Quality assessment may determine inclusion/exclusion and/or sensitivity analyses. Graphical and tabular with narrative commentary. Numerical analysis of measures of effect assuming absence of heterogeneity.

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(2), 91–108. https://doi.org/10.1111/j.1471-1842.2009.00848.x