#3 Rationale - Describe the rationale for the review in the context of existing knowledge.
Cochrane Handbook for Systematic Reviews of Interventions [ebook] by Content experts on the systematic review team should work with the Librarian to determine if similar, recent systematic reviews exist. Content experts may use these recent studies to determine if the research question in Step 1 has been adequately addressed, or whether a different, specific research question needs to be investigated.
These sources are useful for determining whether a recent systematic review has already been performed on your topic. Considering checking these sites first to decide whether a new review is needed.
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Even if there is already a systematic review or meta-analysis on your topic, you may wish to proceed if it is older, if a significant number of new results are availble, if it uses different inclusion/exclusion principles or primary outcomes, or if a significant change has occurred in your field. If you do, it is a good idea to not only cite, but discuss these previous publications in your own article.