A systematic review attempts to identify, appraise and synthesize all available relevant evidence that to answer a specific, focus research question. Researchers conducting systematic reviews use standardized, systematic methods and pre-selected eligibility criteria to reduce the risk of bias in identifying, selecting and analyzing relevant studies.
Prepared by the Cochrane Consumers and Communication Group, La Trobe University and generously support by Cochrane Australia. Written by Jack Nunn and Sophie Hill.
Traditional literature reviews differ from systematic reviews in many ways, and especially on how they are conducted and time commitment required.
When systematic reviews SHOULD be done:
When Systematic reviews SHOULD NOT be done:
Systematic reviews require time and effort to complete. It should not be expected to be complete a systematic review in a matter of months. An average time to complete a systematic review is between 12-18 months. The Cochrane Handbook for Systematic Reviews of Interventions suggests the following timeline to complete a review:
|1 - 2||Preparation of protocol|
|3 - 8||Searches for published & unpublished studies|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|
Cochrane Handbook for Systematic Reviews of Interventions Version 5.1.0 [updated March 2011]. The Cochrane Collaboration, 2011. Available from www.cochrane-handbook.org.
A systematic review can't be done alone. You should carefully consider all of the expertise you will need to define your research question, search for evidence, appraise/grade the evidence, and potentially complete a statistical meta-analysis of the data. A recommended systematic review team would consist of the following: