Comparison of literature searches on quality and costs for health technology assessment using the MEDLINE and EMBASE databases

However, there is considerable variation in the costs of accessing commerci al databases. We sought to measure the quality, amount of overlap, and cost s of information retrieved from two of the main database sources - MEDLINE and EM BASE. Librarians at two health technology assessment agencies ran a total of eight literature searches on various medical technologies, using b oth databases. All search results were independently reviewed by two resear chers. The researchers were asked to identify relevant references and to ra nk each of these according to a level of evidence scale. The results were t abulated to show the number of references identified by each database, the number of relevant references ranked by level of evidence, and the number o f these references that were unique to one or the other database. The cost of retrieving references from each source was also calculated. Each databas e contained relevant references not available in the other. Because of the longer time lag for indexing in MEDLINE, many of the references that origin ally appeared to be unique to EMBASE were subsequently available in MEDLINE as well. Since our study was conducted, MEDLINE has been made available wo rldwide, free of charge, via the Internet. Hence, the cost difference betwe en the databases is now even greater. However, notwithstanding the costs, i t appears that literature searches that rely on only one or the other datab ase will inevitably miss pertinent information.