Designing a search strategy to identify and retrieve articles on evidence-based health care using MEDLINE.

The practice of evidence-based health care requires that information on methodology be identified from databases such as MEDLINE. Up until this year there have been no designated medical subject headings (MeSH) for evidence-based health care. 'EVIDENCE-BASED MEDICINE' appears as a MeSH term from 1997. The absence of designated MeSH for this concept prior to 1997 provides a challenge to the searcher. This paper describes the creation of a MEDLINE search strategy to retrieve articles on the methods of evidence-based health care published prior to the introduction of the new term, where an optimal combination of free-text and MeSH terms is required to identify relevant material. The study examines both free-text and subject heading searching and attempts an optimal balance of sensitivity and specificity. It begins by examining separate free-text and subject heading searches. Sensitivity of the subject heading search was 33% and specificity 80%, while the free-text search produced a sensitivity of 50% and a specificity of 67%. The final strategy, combining both approaches, was more successful with sensitivity reaching between 82 and 90% and specificity 83%. It is therefore possible to devise a search strategy to retrieve articles on the methods of evidence-based health care with relatively successful rates of sensitivity and specificity. The limitations of MEDLINE, however, necessitate the use of additional approaches in identifying articles on the methods of evidence-based health care.