Abstract
OBJECTIVE: To determine the efficiency of the major bibliographic databases by assessing the percentage of references among the total literature available that can be retrieved from each database. We also evaluated the best database combinations to carry out an exhaustive search. METHODS: BIOSIS, EMBASE, MEDLINE, NIOSH-TIC, and TOXLINE were searched on two topics: allergy to latex and asbestos and mesothelioma, in the title, abstract, or keywords (textwords). This search was performed for the years 1994 and 1995. All the records were classified by journal and author's name and were verified for each record whether or not it was indexed in each database. Statistical analysis was performed with chi 2 test. RESULTS: 777 articles in 510 issues were found. The efficiency of each database (percentage of articles recovered) and of combinations varied between 11% and 63% for one database and between 42% and 86% for a combination of two databases. The reasons why these differences exist between databases, and within a database, between two different subjects or two different years are reported. CONCLUSION: Firstly, it is not advisable to assert that a bibliography is complete when only one database is searched. Secondly, the efficiency of the databases may be quite different. Finally, it is suggested that the best way to be as exhaustive as possible is to search two or more databases-for example, in EMBASE and TOXLINE, or to a lesser extent EMBASE and MEDLINE. This seems to be the best compromise solution between time consumed for searching and efficiency.