High-quality systematic reviews are important contributions to medical literature, but how do you know if your research question is the right fit for a systematic review? Here is a quick breakdown of the systematic review process, and what should be considered before embarking on your research journey.
Goal of a Systematic Review
A systematic review attempts to gather and compare all empirical evidence that fits pre-specified eligibility criteria in order to answer a specific research question (1). The Cochrane Handbook gives the following examples as motivation for undertaking a systematic review (2):
- Resolve conflicting evidence
- Address questions where clinical practice is uncertain
- Explore variations in practice
- Confirm the appropriateness of current practice
- Highlight a need for future research
Conducting a systematic review takes time because the methods must be replicable and systematic to minimize bias (1). The PRISMA checklist gives an overview of the steps, including screening the studies for eligibility, assessing risk of bias, and synthesizing the results (3). The Cochrane Handbook gives an estimated timeline for conducting a systematic review as 12 months (4).
Define Your Question
Systematic reviews usually evaluate randomized trials or interventions. One way to outline your research question is the PICO format:
- Comparison intervention
The question does not necessarily have to evaluate RCTs, and can even be qualitative, but the homogeneity of the studies will need to be evaluated to see if the evidence can be collated properly.
Conduct a Preliminary Search
- Make sure there are studies that you can include in your analysis.
- Are there too many studies or results? Although not always the case, it’s possible that your question is too broad.
- Determine if a systematic review has already been published on your topic.
- If there is a systematic review published, does your question or inclusion/exclusion criteria improve on what’s been done? Or is there more evidence available since the existing systematic review was published?
Please contact Becker Library if you would like help with your preliminary search. We are happy to help search databases to find example articles and or to check for existing systematic reviews.
Most guidelines suggest using a librarian to design and run the searches for systematic reviews. Find out more at https://becker.wustl.edu/services/systematic-reviews.
Not A Systematic Review?
If there are not enough/too many studies to include, or if the existing systematic review cannot be improved, you might want to rethink your question or study type.
There are other kinds of reviews that might fit your question. There are at least 14 different review types defined by Grant and Booth (5). For example, scoping reviews map the key concepts that are the foundation of a research area (6), while rapid reviews assess what is known about a policy or practice. Becker librarians can also help you with searching the literature for these kinds of reviews, or help you navigate which type is right for you.
1. Higgins JPT, Green S (editors). Cochrane Handbook for Systematic Reviews of Interventions Version 5.1.0 [Updated March 2011]. The Cochrane Collaboration, 2011. Available from www.cochrane-handbook.org., Section 1.2.2
2. Higgins JPT, Green S (editors). Cochrane Handbook for Systematic Reviews of Interventions Version 5.1.0 [Updated March 2011]. The Cochrane Collaboration, 2011. Available from www.cochrane-handbook.org., Section 2.3.1
3. Moher D, Liberati A, Tetzlaff J, Altman DG, PRISMA Group. Preferred Reporting Items for Systematic Reviews and Meta-analyses: The PRISMA Statement. PLoS Med. 2009 Jul 21; 6(7):e1000097.
4. Higgins JPT, Green S (editors). Cochrane Handbook for Systematic Reviews of Interventions Version 5.1.0 [Updated March 2011]. The Cochrane Collaboration, 2011. Available from www.cochrane-handbook.org., Box 2.3.b
5. Grant MJ, Booth A. A typology of reviews: an analysis of 14 review types and associated methodologies. Health information and libraries journal. Jun 2009;26(2):91-108.
6. The Joanna Briggs Institute. Joanna Briggs Institute Reviewers’ Manual: 2015 edition / Supplement. The Joanna Briggs Institute, 2015.