Downloaded from ebn.bmj.com on August 4, 2012 - Published by group.bmj.
com
Research made simple
What is a systematic review?
Jane Clarke
10.1136/ebn.2011.0049 A high-quality systematic review is described as the most The first step in a systematic review is a meticulous search
reliable source of evidence to guide clinical practice. The of all sources of evidence for relevant studies. The databases
purpose of a systematic review is to deliver a meticulous and citation indexes searched are listed in the methodology
Correspondence to: summary of all the available primary research in response section of the review. Next, using predetermined reproduc-
Jane Clarke
to a research question. A systematic review uses all the ible criteria to screen for eligibility and relevance assess-
4 Prime Road,
existing research and is sometime called ‘secondary ment of titles and the abstracts is completed. Each study is
Grey Lynn, Auckland,
New Zealand; research’ (research on research). They are often required then assessed in terms of methodological quality.
janeclarkehome@gmail.com by research funders to establish the state of existing Finally, the evidence is synthesised. This process may
knowledge and are frequently used in guideline develop- or may not include a meta-analysis. A meta-analysis
ment. Systematic review findings are often used within is a statistical summary of the findings of independent
the healthcare setting but may be applied elsewhere. studies.4 Meta-analyses can potentially present more pre-
For example, the Campbell Collaboration advocates the cise estimates of the effects of interventions than those
application of systematic reviews for policy-making in derived from the individual studies alone. These strate-
education, justice and social work. gies are used to limit bias and random error which may
Systematic reviews can be conducted on all types of arise during this process. Without these safeguards, then,
primary research. Many are reviews of randomised tri- reviews can mislead, such that we gain an unreliable
als (addressing questions of effectiveness), cross-sec- summary of the available knowledge.
tional studies (addressing questions about prevalence The Cochrane Collaboration is a leader in the produc-
or diagnostic accuracy, for example) or cohort studies tion of systematic reviews. Cochrane reviews are pub-
(addressing questions about prognosis). When qualitative lished on a monthly basis in the Cochrane Database of
research is reviewed systematically, it may be described Systematic Reviews in The Cochrane Library (see: http://
as a systematic review, but more often other terms such www.thecochranelibrary.com).
as meta-synthesis are used.
Systematic review methodology is explicit and precise Competing interests None.
and aims to minimise bias, thus enhancing the reliability
of the conclusions drawn.1 2 The features of a systematic References
review include: 1. Antman EM, Lau J, Kupelnick B, et al. A comparison of
results of meta-analyses of randomized control trials and
■ clear aims with predetermined eligibility and rel- recommendations of clinical experts. Treatments for myocardial
evance criteria for studies; infarction. JAMA 1992;268:240–8.
2. Oxman AD, Guyatt GH. The science of reviewing research. Ann
■ transparent, reproducible methods;
N Y Acad Sci 1993;703:125–33; discussion 133–4.
■ rigorous search designed to locate all eligible studies; 3. Higgins JPT, Green S, eds. Cochrane Handbook for Systematic
Reviews of Interventions: Version 5.1.0. The Cochrane
■ an assessment of the validity of the findings of the Collaboration, 2011. http://www.cochrane-handbook.org
included studies and (accessed).
4. Glass G. Primary, secondary, and meta-analysis of research.
■ a systematic presentation, and synthesis, of the Educational Researcher 1976;5:3–8.
included studies.3
64 Evidence-Based Nursing July 2011 | volume 14 | number 3 |
Downloaded from ebn.bmj.com on August 4, 2012 - Published by group.bmj.com
What is a systematic review?
Jane Clarke
Evid Based Nurs 2011 14: 64
doi: 10.1136/ebn.2011.0049
Updated information and services can be found at:
http://ebn.bmj.com/content/14/3/64.full.html
These include:
References This article cites 3 articles, 1 of which can be accessed free at:
http://ebn.bmj.com/content/14/3/64.full.html#ref-list-1
Article cited in:
http://ebn.bmj.com/content/14/3/64.full.html#related-urls
Email alerting Receive free email alerts when new articles cite this article. Sign up in
service the box at the top right corner of the online article.
Topic Articles on similar topics can be found in the following collections
Collections
Research made simple (4 articles)
Notes
To request permissions go to:
http://group.bmj.com/group/rights-licensing/permissions
To order reprints go to:
http://journals.bmj.com/cgi/reprintform
To subscribe to BMJ go to:
http://group.bmj.com/subscribe/
