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Systematic Reviews

A guide for finding standards, procedures, resources, and assistance in supporting systematic searches of the biomedical literature.


What is a systematic review?
A review of a clearly formulated question that uses systematic and explicit methods to identify, select and critically appraise relevant research, and to collect and analyse data from the studies that are included in the review. (

How is a systematic review different from traditional review articles?

  • Systematic reviews attempt to identify all relevant studies, including unpublished studies
  • Systematic reviews describe their methodology in detail and include the literature search strategy, study selection criteria, assessment of study quality, and data synthesis
  • A systematic review may also include a meta-analysis, a quantitative analysis of pooled data

Systematic Reviews and Traditional Narrative Reviews Compared:

  Good Quality Systematic Reviews Traditional Narrative Reviews

Deciding on review question

Start with clear question to be answered or hypothesis to be tested

May also start with clear question to be answered, but they more often involve general discussion of subject with no stated hypothesis

Searching for relevant studies

Strive to locate all relevant published and unpublished studies to limit impact of publication and other biases

Do not usually attempt to locate all relevant literature

Deciding which studies to include and exclude

Involve explicit description of what types of studies are to be included to limit selection bias on behalf of reviewer

Usually do not describe why certain studies are included and others excluded

Assessing study quality

Examine in systematic manner methods used in primary studies, and investigate potential biases in those studies and sources of heterogeneity between study results

Often do not consider differences in study methods or study quality

Synthesizing study results

Base their conclusions on those studies which are most methodologically sound

Often do not differentiate between methodologically sound and unsound studies

Reference: Systematic reviews from astronomy to zoology: myths and misconceptions. BMJ. 2001 Jan 13;322(7278):98-101.

Literature Reviews & Systematic Reviews - NYU Washington Square:

Guidelines for Conducting & Reporting Systematic Reviews

IOM Standards

Finding What Works in Health Care: Standards for Systematic Reviews. Consensus Report. Institute of Medicine of the National Academies, 2011 March 23.

The PRISMA Statement

Moher D, Liberati A, Tetzlaff J, Altman DG, The PRISMA Group (2009). Preferred Reporting Items for Systematic Reviews and Meta-Analyses: The PRISMA Statement. PLoS Med 6(6): e1000097. doi:10.1371/journal.pmed1000097