MEDLINE, EMBASE, and Cochrane index most primary studies but not abstracts included in orthopedic meta-analyses.
To test the hypothesis that all primary studies used in orthopedic meta-analyses are indexed in MEDLINE or EMBASE. Using MEDLINE from 1995 to 2005, we retrieved all published meta-analyses of orthopedic surgical interventions. The primary studies in each meta-analysis were defined as the "gold standard" set. MEDLINE and EMBASE were searched for each primary study, and a recall rate was calculated. Secondary searches were performed using Web of Science (WoS), the Cochrane databases, and CINAHL. High recall rates were achieved searching MEDLINE (90%) and EMBASE (81%) for the gold standard set, and the combined search retrieved 91%. Titles not indexed by MEDLINE or EMBASE included 45 abstracts, eight journal articles, and three unpublished studies. Searching the Cochrane databases yielded 36 titles not in MEDLINE or EMBASE. Using all three databases produced 97% recall of the primary studies; WoS and CINAHL did not increase the recall rate. These results suggest that a very high percentage of primary research in orthopedics can be found using the major databases. Additional database searches are unlikely to increase the yield of published manuscripts; however, conference proceedings and journal supplements should still be searched to ensure that relevant remaining reports are identified.