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Systematic Reviews

What is a systematic review?

A systematic review collates and summarizes all results from research studies, based on strict eligibility criteria, to provide a high level of evidence on the effectiveness of an intervention. Key components of a systematic review include a clear and well-defined question, inclusion & exclusion criteria, a thorough search of the available literature, screening for eligibility, a critical appraisal of all included studies, data extraction and management, results analysis and synthesis, and dissemination of results.

To be sure of the type of review that you are doing, check this typology of review types (Grant & Booth 2009).

What does it take to do a systematic review?

Time. In most cases it takes 12-18 months to complete a systematic review.

People. You will need a team comprised of people with different areas of expertise. At the very least this includes subject experts, librarians, screeners/reviewers, and a biostatistician. Cochrane review teams are encouraged to include consumers and clinicians representing different regions and settings. One person should be identified as the primary contact and project lead.

A research question. A clearly defined question is essential. Use the PICO (Population, Intervention, Comparison, Outcome) formula to identify key components of your question. This will also inform your inclusion/exclusion criteria.

A gap in the literature. Once you have your question, a search of the literature is required to ensure that this topic has not already been addressed in a systematic review or that an existing review on the topic could be updated.

A protocol. This is your plan. It should include your research question including PICO components, eligibility criteria, literature search parameters (published and nonpublished literature), screening methods, data extraction/abstraction methods, critical appraisal method, data analysis/synthesis methods, data management plan, and evidence grading. Cochrane protocols have additional requirements. It is a good idea to register your protocol with Prospero, an international database of registered systematic reviews that have a health related outcome. It's free to register.

An exhaustive literature search. This includes database selection as well as identification of key concepts, terms and phrases for search strategies. Normally this is done by a librarian with specific training and expertise in search strategies for systematic reviews. You can expect this to take at least three weeks. Search results are normally exported into a citation management tool such as Endnote, Refworks, Mendelay, etc. PRESS (Peer Review of Electronic Search Strategies) outlines expectations for systematic review searches.

Review management software. While you can do a systematic review without it, review management software makes it much easier. The HSL has purchased Covidence for your use if that is your preference.

Reporting. Best practice for systematic review reporting is outlined in PRISMA.

Systematic Review Guides

What Support Do You Need?

What level of support do you need?

  • We will look after all aspects of the literature search including database selection, design and translation of search strategies, citation management, PRISMA flowchart, and a written search methodology. For this level of support we are a named author.
  • We will provide consultative support while your team develops and performs all search strategies and related activities. For this level of support we are delighted to be acknowledged in the final paper for our contribution.
  • We will answer any questions you have on how to do systematic review.
  • Further information can be found in our Systematic Reviews Policy.