Health Science Specialist Evidence Synthesis Program Coordinating Center / Portland VA Health Care System Boise, Idaho
Objectives: Rapid reviews are often used to support healthcare decision-making and can include non-randomized studies (NRS) when randomized studies are not available. However, NRS can be more complex and resource-intensive to identify and synthesize than randomized studies. It is currently unclear if and how NRS complexity is managed over the shortened time frames of rapid reviews.
Methods: A sample of rapid reviews published in the last five years was extracted from Ovid MEDLINE by searching for “rapid review” in the title field; rapid reviews focused on a health care interventions were included in the sample. The sample of rapid reviews was assessed with descriptive statistics and thematic analysis for the following criteria: 1) inclusion of NRS versus randomized studies; 2) search strategy terms for NRS; 3) inclusion/exclusion criteria regarding NRS; 4) screening, assessment, and extraction of NRS; 5) strategies for prioritizing synthesis of NRS; and 6) conclusions drawn from NRS.
Results: The search retrieved 23 rapid reviews that met our inclusion criteria and of these reviews, 14 (61%) included NRS. Only one review used NRS-specific terms in its search strategy, but half of the reviews (n=14) used NRS-specific inclusion criteria. In terms of the approaches used for full-text screening, quality assessment and data extraction, rapid reviews with NRS display greater variability than rapid reviews with no NRS. Each of the rapid reviews with both RCTs and NRS (n=10) synthesized all study types together, rather than using a prioritization method that would exclude NRS from the final synthesis.
Conclusions: The results of this study highlight some of the areas of complexity that emerge when NRS are included in rapid reviews of health interventions. While there is greater variation in certain aspects of rapid review methods when NRS are included, the approach to synthesizing results of reviews with NRS is similar to reviews with no NRS. Given the inconsistency in whether NRS are included in rapid reviews and if so, how they are included and evaluated, there is a need for standardized methodology for including, evaluating and synthesizing NRS in rapid reviews. This would improve the impact of rapid reviews with NRS on decision-making in rapidly changing fields or situations.