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WHSL Clinical Questions using PubMed: Systematic Reviews

The first in a series of evidence-based medicine guides


  1. The consolidation of research evidence that incorporates a critical assessment and evaluation of the research (not simply a summary) and addresses a focused clinical question using methods designed to reduce the likelihood of bias.
  2. The identification, selection, appraisal, and summary of primary studies addressing a focused clinical question using methods to reduce the likelihood of bias.

JAMAevidence Glossary. Available:

[Accessed 22.02.2011]

What is a Systematic Review?

Systematic Reviews are not the same as Reviews. A review is a narrative article, whereas a systematic review has rigorous requirements for use in evidence-based medicine (see Definitions). A systematic review is a thorough, comprehensive and explicit way of interrogating the medical literature.

Systematic reviews include several steps:

  1. A precise formulation of the problem
  2. Identification of one or more databases to search
  3. Efficient search strategies
  4. Rigorous appraisal of the research designs, implementations and analyses
  5. Systematic (not merely selective) synthesis of information
  6. Justified conclusions
  7. Identification of gaps in present knowledge
  8. Abstracting the data in a standardised format

Systematic reviews are regarded as the "Gold Standard" of evidence in the literature.


A meta-analysis is a statistical approach to combine the data derived from a systematic-review. Therefore, every meta-analysis should be based on an underlying systematic review, but not every systematic review leads to a meta-analysis.