Development of a highly sensitive search strategy for the retrieval of reports of controlled trials using PubMed.

OBJECTIVE To develop, through revision of the Cochrane Collaboration search strategy for OVID-MEDLINE, a highly sensitive search strategy to retrieve reports of controlled trials using PubMed. METHODS The original highly sensitive Cochrane strategy was revised to take into account additional Medical Subject Headings (MeSH) and other terminology as well as the current unique features of PubMed. We compared the retrieval of the revised strategy with that of the original Cochrane strategy before and after translation of the strategies into PubMed format. Finally, we used a gold standard database of reports of controlled trials identified by electronic and hand search of selected journals to test the revised strategy in PubMed format. RESULTS The revised strategy included a search statement modified for increased precision, and added 'Cross-over Studies' as a MeSH term and the term 'latin square' as a text word. Compared to the original Cochrane strategy, the revised strategy identified 53 additional reports of controlled trials accessing MEDLINE through OVID. When the revised strategy and original Cochrane strategy were translated into PubMed format, the revised strategy retrieved 90 reports of controlled trials not identified by the original strategy. Finally, the revised strategy in PubMed format retrieved all of the reports of controlled trials in the gold standard database. Ninety-eight per cent of the gold standard reports of controlled trials were retrieved by Phase 1 of the optimal PubMed search strategy. CONCLUSIONS Failure to identify all relevant trials for systematic review could result in bias. We developed a highly sensitive search strategy for the retrieval of reports of controlled trials for use with PubMed that retrieves more relevant citations (greater sensitivity) and fewer non-relevant citations (greater precision) than the original Cochrane search strategy.