The efficiency of database searches for creating systematic reviews was improved by search filters.

Objectives: To compare Clinical Queries (CQs) for randomized trials of therapy 'methods' and 'NOT' limits search filters with Cochrane methods filters.

Study Design And Setting: Analytic survey of Cochrane reviews as the reference standard for retrieving studies included in the reviews ("included studies [ISs]"). The sensitivity and precision of Cochrane content terms + Cochrane methods terms were compared in MEDLINE and Embase with Cochrane content terms + CQs maximally sensitive filter for therapy studies, without and with additional 'NOT' limits (CQ-S [CQ sensitive]; CQ-S + limits) and a balanced filter without and with additional NOT limits (CQ-B [CQ balanced]; CQ-B + limits).

Results: Cochrane or CQ methods terms reduced, by 64-96%, the overall retrieval of articles with minimal loss of ISs. Sensitivity was high and similar for the 4 filters. However, CQ-B + limits had the highest precision (2.64%, number needed to be read to find one eligible study [NNR] 38) followed by the CQ-B (1.05%, NNR 95), Cochrane search (0.51%, NNR 198), CQ-S + limits (0.34%, NNR 296), and CQ-S filters (0.31%, NNR 325).

Conclusion: For systematic reviews of therapeutic interventions, the efficiency of searches in MEDLINE and Embase was better served by the CQs for therapy studies with balanced methods filter and NOT limits.