Objective: To determine the reasons for the loss of sensitivity and specificity of methodologic MeSH terms and textwords in MEDLINE for identifying sound clinical studies of the etiology, prognosis, diagnosis, prevention, or treatment of disorders in adult general medicine.

Design: Analytic survey of the information retrieval properties of methodologic MeSH terms and textwords selected to detect studies meeting basic methodologic criteria for direct clinical use in general adult medicine.

Measures: Frequency of non-use and misuse of relevant methodologic MeSH terms and textwords among studies meeting and not meeting the basic criteria for clinical practice as determined by the manual review (the gold standard) of all articles in 10 internal and general medicine journals for 1986 and 1991.

Results: Loss of sensitivity due to the non-use of relevant methodologic terms among articles meeting basic methodologic criteria was more pronounced in the areas of diagnosis, prognosis, and etiology than treatment in 1991 and 1986. The use of relevant methodologic terms has improved from 1986 to 1991 in all areas except prognosis. Loss of specificity due to the use of relevant methodologic terms among articles not meeting basic methodologic criteria occurred most frequently in the areas of treatment and etiology.

Conclusions: Although the appropriate use of methodologic MeSH and textwords has improved from 1986 to 1991 among studies meeting basic methodologic criteria for direct clinical use in general adult medicine much improvement is still needed in the areas of diagnosis, prognosis, and etiology. Improvement is needed in assigning the relevant methodologic index terms to studies that meet the methods criteria and in having the authors use the relevant methodologic textwords in the title or abstract. Some improvement is also needed in not using methodologic terms when the study clearly does not meet the methods criteria.