Written by Julie Fricke (Systematic Review Analyst) and Neil Webb (Head of Systematic Review)
As described in the Cochrane Collaboration Handbook, a systematic literature review (SLR) attempts to collate all empirical evidence that fits pre-specified eligibility criteria in order to answer a specific research question (primarily to aid in decision-making). It uses explicit, systematic methods that are selected with a view to minimizing bias, thus providing more reliable findings from which conclusions can be drawn [1, 2]. Although considered the gold standard of quality research, SLRs are very resource-intensive. According to Petticrew et al. (2006), SLRs take an average of 1,139 hours (range 216 to 2,518 hours) to complete and usually require a budget of at least $100,000 .
What is a rapid review?
Driven by a need for fast and low-cost evidence synthesis for timely health care and policy decisions, an evolving alternative to the SLR is the rapid review, which is usually conducted in 1-12 weeks. There is not yet a formal definition of a rapid review, but it can be considered a “form of knowledge synthesis in which components of the systematic review process are simplified or omitted to produce information in a timely manner” . Rapid reviews are primarily commissioned by government agencies and health ministries , and are increasingly used within health technology assessment (HTA) .
Approaches and value of rapid reviews
There are various approaches for simplifying the review components. Tricco et al. (2015) conducted a scoping review of rapid review methods which identified 100 articles reporting on these approaches . Identified approaches included:
- limiting the literature search to published literature or one database
- limiting inclusion criteria by date or language
- having one reviewer screen and abstract data and another verify
- not conducting risk of bias/quality appraisal
- having only one reviewer conduct the appraisal
- presenting results as a narrative summary
However, given that rapid reviews are relatively new, there is still an ungainly collection of different techniques used with varying terminology . There are many published articles on rapid review methods, but little pragmatic guidance on which methods to select.
Considering this lack of guidance, researchers from the University of Sheffield within the School of Health and Related Research (ScHARR) developed a tool to outline high-level approaches to the rapid review process, rather than defining detailed review methods . The tool covers interaction with review commissioners, understanding the evidence base, data extraction and synthesis methods, and reporting of rapid review methods.
Implementation and words of caution
Notably, because rapid reviews streamline the review process, they must remain systematic by adhering to the core principles of SLRs that avoid bias in the inclusions, assessment, and synthesis of studies . Deviations from traditional SLR methods should be laid out clearly in the methods section. Speed is not a predictor of the quality of a review if conduct is maintained, and there is no evidence available to suggest that rapid reviews should not be done or that they are misleading in any way .
As the use of rapid reviews continues to grow, a standardised and transparent approach is needed with a rigorous method of evaluation. In situations with a limited budget and timeframe, rapid reviews may provide a viable alternative to an SLR.
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- Oxman, A.D. and G.H. Guyatt, The science of reviewing research. Ann N Y Acad Sci, 1993. 703: p. 125-33; discussion 133-4.
- Petticrew, M., Systematic Reviews in the Social Sciences: A Practical Guide. Counselling and Psychotherapy Research, 2006. 6(4): p. 304-305.
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- Tricco, A.C., et al., A scoping review of rapid review methods. BMC Med, 2015. 13: p. 224.
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- Haby, M.M.C., E; Clark, R; Barreto, j; Reveiz, L; Lavis, J.N., What are the best methodologies for rapid reviews of the research evidence for evidence-informed decision making in health policy and practice: a rapid review. Health Research Policy and Systems, 2016. 14(83).