Systematic Reviews and other evidence synthesis projects

Does a systematic review already exist on your topic? Is a systematic review currently in progress on the same topic? Once you have a reasonably well defined research question, it is important to make sure your project has not already been recently and successfully undertaken. This means it is important to find out if there are other knowledge syntheses that have been published or that are in the process of being published on your topic.

A few reasons to search:

• To reduce the likelihood that a publisher will have already published or received a similar manuscript recently.
• To make a good case that your review or synthesis is needed and not duplicating recent extant work when submitting your proposal for funding.
• Looking at other knowledge syntheses published around your topic may help you refocus your question or redirect your research toward other gaps in the literature.

It is also important to note that what is considered “recent” will depend on your discipline and the topic.
 

Some options if you find that there is already a systematic review or meta-analysis—or protocol for one—on your topic:

• If it is older, if a significant number of new results are available, if it uses different inclusion/exclusion principles or primary outcomes, or if a significant change has occurred in your field, you may wish to proceed. If you do, it is a good idea to not only cite, but discuss these previous publications in your own article.
• Adjust your project somewhat so that it is supplements the extant review instead of duplicating it.
• Significantly change your project

Run a search on a basic version of your search concepts in the following databases to check for extant protocols and/or systematic reviews.

• PROSPERO
  International prospective register of systematic reviews, rapid reviews, and umbrella reviews in health sciences and in social sciences where there is a health-related outcome.
• Cochrane Library
  Includes all Cochrane Reviews and protocols for Cochrane Reviews. Select the Reviews or Protocols tab to read the results.
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• Journals that publish protocols
  • BMC Systematic Reviews: https://systematicreviewsjournal.biomedcentral.com/
  • JMIR Research Protocols: https://www.researchprotocols.org/
  • JBI Evidence Synthesis: https://journals.lww.com/jbisrir/pages/default.aspx
  • BMJ Open: https://bmjopen.bmj.com/
• PubMed
  To find extant systematic reviews and meta-analyses, enter a basic version of your search concepts plus AND (systematic review*[tw] OR meta-analys*[tw]). This will not be a comprehensive search for all possible systematic reviews and meta-analyses, but it will locate many of them.
  Example: (smoking cessation) AND (hypnosis) AND (acupuncture) AND (systematic review*[tw] OR meta-analys*[tw])
• Embase
  To find extant systematic reviews and meta-analyses, enter a basic version of your search concepts plus AND ('systematic review*' OR 'meta-analys*'). This will not be a comprehensive search for all possible systematic reviews and meta-analyses, but it will locate many of them.
  Example: (smoking cessation) AND (hypnosis) AND (acupuncture) AND ('systematic review*' OR 'meta-analys*')
• Other databases
  If your research question may have articles in journals outside of health sciences, such as social science or engineering, a similar search string can be constructed for major databases in that field. Ask a librarian if you need assistance constructing it.