In 2013 I presented “If Rapid Reviews are the Answer, What is the Question?” at the Guidelines International Network (G-I-N) conference in San Francisco. My interest in rapid review began in New York the year before at the Evidence-Based Guidelines Affecting Policy Practice and Stakeholders (EGAPPS) conference. Several colleagues shared that they were also concerned about confusion from adding rapid review to our nomenclature so soon after the Institute of Medicine standardization of systematic review methods. This prompted me to search for standards describing:
o What is a rapid review?
o When should it, or shouldn’t it, be used?
o How does it differ from systematic or other evidence reviews?
I shared what I learned at the conference.
Now two years later, I wondered if we are closer to answers.
If you start with the simplest question, “What defines a rapid review?” it’s tempting to provide the simplest answer. It must be speed in completing the review, right? But this doesn’t address how the speed is achieved. What parts of the review become rapid? And what is meant by rapid? As you’ll see, that too is relative.
Several others have looked at what a rapid review might be. At the time of my presentation, I included three systematic looks at rapid review. (References 1,2,3)
Watt defined rapid review as a health technology assessment or systematic review that takes one to six months to produce. Ganaan defined it as literature review that accelerates systematic review and Harker was most generous allowing anything that calls itself a rapid review. The results were uniform in finding variability in:
o Time to completion
Most surprising was the finding that the time frame for “rapid” varies considerably and is relative. Harker reported a mean time for completion (10.42 months) that was not much shorter than that for systematic review!
All authors found that rapid review developers made different choices about where to achieve speed. Choices such as:
o Narrowing breadth of review question
o Limiting sources searched
o Limiting time-frame for search
o Eliminating or limiting quality review
o Limiting depth of analysis
In many instances, the rapid review developers were not fully transparent about the potential for introducing bias resulting from each of these short cuts.
All three of these authors had built an assumption into their assessments - that rapid review is a faster systematic review. But is it? I'd heard presentations by organizations that have implemented rapid reviews using a technique considered by others, like Cochrane, to be an overview of reviews. Instead of rapid assessment of primary literature, they find and synthesize secondary literature, specifically existing systematic reviews.
That led me to conduct an internet search for rapid reviews created by various organizations. I confirmed that many developers of rapid review products were not reviewing primary literature, but were evaluating secondary literature. So it wasn’t always about speedy creation of a de novo systematic evidence review, but was often about creating a user-friendly assessment of existing evidence, usually from prior systematic review. The commonality was what precipitated the rapid review, generally a user request for a quick answer and often to support policy decisions.
So a Rapid Review could be a:
o Type of review that uses shortcuts reducing rigor and increasing the risk of introducing bias
o Translated, user-friendly product using existing systematic reviews
o Transformed systematic review process that shortens time spent in production without sacrificing rigor
Rapid review may be a label attached to a quick and dirty process that introduces selection bias in the search for and information bias in the evaluation of evidence.
Or it may mean a systematic appraisal of secondary research designed to meet user needs.
Or it may mean improved process methods that can accelerate SR timeline without reducing rigor. Things like increasing available resources, or implementing leaner processes during the development phase, or automating steps where the technology is ready.
Is rapid review a phase of the systematic review process?
To further complicate the issue, I did find that some organizations use the label rapid review when describing a kind of quick scoping review, used to look for major trends or patterns in research. These developers generally acknowledge that their review was not systematic but rather a pre-systematic review that indicated need for or ability to conduct thorough review. In that context, the rapid review could fit before a systematic review. The more common use by organizations was as a translated or aggregated product based on existing systematic review. In that use, the rapid review was more like a knowledge translation product built from existing systematic review.
In February of this year, the Agency for Healthcare Research and Quality Evidence-based Practice Centers’ Methods Workgroup released “An Exploration of Methods and Context for the Production of Rapid Reviews” (reference 4) to address these issues. They combined literature review with key informant interviews and confirmed previous findings that rapid review has no standard meaning and the products are highly variable.
Here are my suggestions based on what I’ve learned.
1. Stop using the label rapid review. It has no meaning and adds to confusion about evidence reviews.
2. Use the label scoping review when a user wants a quick first look at what evidence may exist for their question.
3. Use either the label "overview of reviews" or "systematic review of systematic reviews" when describing an evaluation of existing systematically derived evidence summaries.
4. Work together to improve systematic review processes so we can create evidence reviews in shorter time frames without sacrificing rigor.
1. Watt A et al. Rapid Reviews vs. Full Systematic Reviews. International Journal of Technology Assessment in Health Care, 24:2 (2008), 133–139.
2. Ganann R, Ciliska D, Thomas H. Expediting systematic reviews: methods and implications of rapid reviews. Implement Sci. 2010;5:56.
3. Harker J, Kleijnen J. What is a rapid review? A methodological exploration of rapid reviews in Health Technology Assessments. Int J Evid Based Healthc. 2012;10:397–410.
4. Hartling L et al. EPC Methods: An Exploration of Methods and Context for the Production of Rapid Reviews. Research White Paper. AHRQ Publication No. 15-EHC008-EF. Rockville, MD: Agency for Healthcare Research and Quality; February 2015. www.effectivehealthcare.ahrq.gov/reports/final.cfm.
TheEvidenceDoc July 2015