Crossover Comparison of Drug Information Online Database Vendors: Dialog and Medlars

Abstract

OBJECTIVE: To compare Dialog EMBASE with the National Library of Medicine's (NLM's) MEDLARS MEDLINE, TOXLINE, and TOXLIT to evaluate differences among the databases and vendors in a method consistent with routine drug information practice. DESIGN: Crossover comparison. METHODS: NLM MEDLARS databases MEDLINE, TOXLINE, and TOXLIT were searched directly. EMBASE was searched via Dialog Information Services. MEDLINE was searched back to 1980; TOXLINE and TOXLIT were searched back to 1981, reflecting the different database structures. EMBASE was searched back to 1980. To control bias, searches were randomized; identical strategies were used during the same session and were performed by the same trained searcher. RESULTS: Twenty-six drug information requests were compared. The MEDLARS and Dialog databases were generally similar, with no significant differences in the number of potentially relevant references, English references, clinically relevant references, available abstracts, unique citations, time online, and number of questions answered. EMBASE searches were more costly (p=0.0005). TOXLIT was costlier than TOXLINE and MEDLINE (p=0.0018). CONCLUSIONS: NLM MEDLARS databases were comparable to Dialog EMBASE. Although MEDLARS provided more total and English-language citations, the differences were small and did not influence the proportion of questions answered. The greatest difference between the vendors was the significantly lower cost of searching on MEDLARS. Although this difference may be partially offset by the significantly shorter search times on EMBASE, the mean 1.9 minutes saved would not recoup the mean $7.89 difference in cost. MEDLARS databases are less expensive for routine drug information requests.