A systematic review is a high-level overview of primary research on a particular research question that tries to identify, select, synthesize and appraise all high quality research evidence relevant to that question in order to answer it. – Definition from Cochrane Collaboration
A clearly stated set of objectives with pre-defined eligibility criteria for studies:
[Cochrane Handbook for Systematic Reviews of Interventions, 2011]
The systematic review process has been developed to minimise bias and ensure transparency. Methods should be adequately documented so that they can be replicated. The systematic review is an approach used in health, education and social policy (as part of evidence based policy or practice) and is much more than a 'literature review' because it follows a strict methodology which means it is 'transparent, rigorous and replicable.'
When conducted well, systematic reviews should give us the best possible estimate of any true effect. An assessment of the methodological quality of reviews should highlight the limitations of a review.
Systematic reviews are gaining in popularity at medical research institutions across Europe and America.
|1 – 2||Preparation of protocol|
|3 – 8||Searches for published and unpublished studies|
|2 – 3||Pilot test of eligibility criteria|
|3 – 8||Inclusion assessments|
|3||Pilot test of ‘Risk of bias’ assessment|
|3 – 10||Validity assessments|
|3||Pilot test of data collection|
|3 – 10||Data collection|
|3 – 10||Data entry|
|5 – 11||Follow up of missing information|
|8 – 10||Analysis|
|1 – 11||Preparation of review report|
|12 –||Keeping the review up-to-date|
Source: Higgins JPT, Green S (editors). Cochrane Handbook for Systematic Reviews of Interventions Version 5.1.0 [updated March 2011]. The Cochrane Collaboration, 2011. Browse the Handbook Online
Narrative reviews: Broad perspective on topic (like a textbook chapter), no specified search strategy, significant bias issues, may not evaluate quality of evidence
Structured reviews: Includes a structured, but limited search, less bias, but not comprehensive, usually evaluates quality of evidence; a partial systematic review
Systematic reviews: Comprehensive with minimized bias, based on specific question and criteria with a pre-planned protocol, evaluates quality of evidence
Scoping Reviews: An overview of the literature on a broader topic; often done to identify whether a systematic review is feasible.