Systematic Reviews

What is a Systematic Review?

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.
(Chapter 1.2.2, Higgins JPT, Green S (editors). Cochrane Handbook for Systematic Reviews of Interventions Version 5.1.0 [updated March 2011]. The Cochrane Collaboration, 2011. Available from www.cochrane-handbook.org.)

What is a Systematic Review? (.pdf)
(From Bandolier and Oxford University)

A practical guide to understanding systematic reviews and meta-analyses.
Neely JG, et al. Otolaryngol Head Neck Surg. 2010 Jan;142(1):6-14. doi: 10.1016/j.otohns.2009.09.005.

What is in a Systematic Review
Systematic review product diagram from YourHealthNet, "Navigating Effective Treatments With Systematic Reviews: An online toolkit that will help you understand and develop the skills to explore health research" developed and published by the Centre for Health Communication and Participation with support from the Australasian Cochrane Centre.

What is a Meta-analysis?

Many systematic reviews contain meta-analyses. Meta-analysis is the use of statistical methods to summarize the results of independent studies (Glass 1976). By combining information from all relevant studies, meta-analyses can provide more precise estimates of the effects of health care than those derived from the individual studies included within a review (see Chapter 9, Section 9.1.3). They also facilitate investigations of the consistency of evidence across studies, and the exploration of differences across studies.
(Chapter 1.2.2, Higgins JPT, Green S (editors). Cochrane Handbook for Systematic Reviews of Interventions Version 5.1.0 [updated March 2011]. The Cochrane Collaboration, 2011. Available from www.cochrane-handbook.org.)

What is a meta-analysis? (.pdf)
Meta-analysis is a statistical technique for combining the findings from independent studies.  Meta-analysis is most often used to assess the clinical effectiveness of healthcare interventions; it does this by combining data from two or more randomised control trials.
(From Bandolier and Oxford University)

Meta-analysis in medical research.
Haidich AB. Hippokratia. 2010 Dec; 14(Suppl 1):29-37.

What is a Literature Review?

A literature (sometimes known as a narrative) review intends to provide an overview of a subject. It does not include a systematic search of the literature or a description of the methods used in the review and is sometimes based on author experience.  These reviews may be subject to bias.
 

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