A Two-Term MEDLINE Search Strategy for Identifying Randomized Trials in Obstetrics and Gynecology

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To develop and test a simple MEDLINE search strategy for identification of randomized controlled trials (RCTs) in obstetrics and gynecology.


To develop our search strategy, we asked clinicians in our department to indicate, from a list of search terms, the terms they would use to identify RCTs in MEDLINE. The two most common terms, controlled-clinical-trial (publication type) and randomized-controlled-trial (publication type), were combined with the link word, OR, and then used to identify RCTs in four obstetrics and gynecology journals for the years 1975, 1980, 1985, 1990, and 1995. Concurrently, a handsearch of these same journals and years was performed to identify RCTs. The sensitivity and precision of MEDLINE and handsearch were calculated using the total number of RCTs identified by both methods as a reference standard. Sensitivity is the RCTs identified by search strategy as a percentage of all RCTs identified by reference standard. Precision is the RCTs identified by a search strategy as a percentage of all articles identified by it.


The overall sensitivity of our MEDLINE search strategy was 72.5%, and the precision was 83.4%. Over 2 decades, sensitivity of our MEDLINE search increased from 0% to 94.9% (P < .001), while its precision dropped from 100% to 75.5% (P = .003). For 1990 and 1995 combined, sensitivity and precision of our MEDLINE search strategy were 90.3% and 79.6%, respectively. Overall sensitivity for handsearch was 96.5%; its precision was 5.0%. Over 2 decades, the sensitivity of handsearch dropped insignificantly from 100% to 92.3% (P = .05), while the precision increased from 2.6% to 6.3% (P < .001).


Our simple MEDLINE search strategy has a high sensitivity and precision, especially in more recent years. Obstetricians and gynecologists may use it to search quickly for RCTs to guide patient care.

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