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Health Science and Nutrition: Systematic Reviews

Systematic reviews

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Summary points

A systematic review is an overview of primary studies that used explicit and reproducible methods

A meta-analysis is a mathematical synthesis of the results of two or more primary studies that addressed the same hypothesis in the same way

Although meta-analysis can increase the precision of a result, it is important to ensure that the methods used for the review were valid and reliable

A systematic review is an overview of primary studies which contains an explicit statement of objectives, materials, and methods and has been conducted according to explicit and reproducible methodology 

See also

Systematic Review explained


Prospero: International prospective register of systematic reviews


Guidance on performing a systematic review from the CRD (Centre for Reviews and Dissemination)

A Guide to Conducting Systematic Reviews: Steps in a Systematic Review

Systematic Review: overview

Systematic Review: UCD guide (link added with permission)

Centre for Reviews and Dissemination

National Institute for Health and Care Excellence


Cochrane Handbook for Systematic Reviews of Interventions

Grey Literature Sources

INIST in France (Institute for Scientific and Technical Information) has launched OpenSIGLE, which provides access to all the former SIGLE records

WHO International Clinical Trials Registry Platform

Although conference proceedings are not indexed in MEDLINE and a number of other major databases, they are indexed in the BIOSIS databases

Many conference abstracts are published free of charge on the internet, such as those of the American Society of Clinical Oncology (ASCO):

LENUS: Irish Material

Where to search for Clinical trials: Medline, Embase, Cochrane, Web of Science, Scopus (EMBASE 90), Science Direct, CINAHL , Clinical trials registers, Grey Literature, Subject Specific Databases

How to report a study:  PRISMAEQUATOR, CONSORT

How to assess a study:  GRADE, Newcastle-Ottowa, JADAD

A systematic review attempts to collate all empirical evidence that fits pre-specified eligibility criteria in order to answer a specific research question.  It  uses explicit, systematic methods that are selected with a view to minimizing bias, thus providing more reliable findings from which conclusions can be drawn and decisions made. The key characteristics of a systematic review are:

  •     a clearly stated set of objectives with pre-defined eligibility criteria for studies;
  •     an explicit, reproducible methodology;
  •     a systematic search that attempts to identify all studies that would meet the eligibility criteria;
  •     an assessment of the validity of the findings of the included studies, for example through the assessment of risk of bias; and
  •     a systematic presentation, and synthesis, of the characteristics and findings of the included studies.

(Cochrane Handbook for Systematic Reviews of Interventions, 2011)