Optimizing search strategies to identify randomized controlled trials in MEDLINE

Abstract

BackgroundThe Cochrane Highly Sensitive Search Strategy (HSSS), which contains three phases, is widely used to identify Randomized Controlled Trials (RCTs) in MEDLINE. Lefebvre and Clarke suggest that reviewers might consider using four revisions of the HSSS. The objective of this study is to validate these four revisions: combining the free text terms volunteer, crossover, versus, and the Medical Subject Heading CROSS-OVER STUDIES with the top two phases of the HSSS, respectively.MethodsWe replicated the subject search for 61 Cochrane reviews. The included studies of each review that were indexed in MEDLINE were pooled together by review and then combined with the subject search and each of the four proposed search strategies, the top two phases of the HSSS, and all three phases of the HSSS. These retrievals were used to calculate the sensitivity and precision of each of the six search strategies for each review.ResultsAcross the 61 reviews, the search term versus combined with the top two phases of the HSSS was able to find 3 more included studies than the top two phases of the HSSS alone, or in combination with any of the other proposed search terms, but at the expense of missing 56 relevant articles that would be found if all three phases of the HSSS were used. The estimated time needed to finish a review is 1086 hours for all three phases of the HSSS, 823 hours for the strategy versus, 818 hours for the first two phases of the HSSS or any of the other three proposed strategies.ConclusionThis study shows that compared to the first two phases of the HSSS, adding the term versus to the top two phases of the HSSS balances the sensitivity and precision in the reviews studied here to some extent but the differences are very small. It is well known that missing relevant studies may result in bias in systematic reviews. Reviewers need to weigh the trade-offs when selecting the search strategies for identifying RCTs in MEDLINE.

PubMed had a higher sensitivity than Ovid-MEDLINE in the search for systematic reviews

“…Most search strategies for topics such as RCT [4,11,12], prognostic study [13], or diagnostic study [7,14] were developed specifically to optimize the yield for searching MEDLINE via Ovid [4,11e14] or DataStar [7]. MEDLINE search strategies have been translated for use in PubMed [12,14], but these may not achieve the same sensitivity and precision compared with Ovid-MEDLINE because the syntax for searching in PubMed differs from the syntax in Ovid-MEDLINE.…”

Optimized search strategy for detecting scientifically strong studies on treatment through PubMed

“…Several approaches have been developed to improve retrieval of studies clinically relevant and scientifically sound from similar bibliographic databases [3][4][5][6][7][8][9][10].…”

Unloaded Movement Facilitation Exercise Compared to No Exercise or Alternative Therapy on Outcomes for People with Nonspecific Chronic Low Back Pain: A Systematic Review

“…Additional search words were McKenzie therapy, McKenzie method, McKenzie treatment, centralization, extension exercises, flexion exercises, stretching exercises, passive exercises, movement, tai chi, and yoga. Search strategies followed Cochrane Collaboration recommendations 16 and those of the current literature [22][23][24] and are available from the first author. Databases searched were Medline, Cinahl, Embase, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, PEDro, PubMed, Current Contents, Expanded Academic, Australian Medical Index, and Sport Discus.…”