Determinants of initiation and suboptimal use of anti-ulcer medication: a study of the Quebec older population.

Abstract

To describe the use of anti-ulcer medication in the Quebec older population; to examine determinants of initiation, suboptimal use, and switches between products. Population-based retrospective cohort study. Universal health program for older adults in Quebec. 5000 users and 5000 non-users of anti-ulcer medications were selected randomly. Use was defined as the presence in the 1991 prescription database of an anti-ulcer prescription. Among users, 1697 (34%) were new users and were considered as the exposure group. Subjects were followed for 365 days after inclusion. Measured were patient's age, gender, prescribed duration of anti-ulcer medication, concomitant medications, and gastrointestinal diagnostic procedures. A total of 17% of new users had unusually short courses; 18% were long-term users. There was no difference in duration for omeprazole compared with other anti-ulcer medications. First-time use of NSAIDs was the strongest predictor of initiation of anti-ulcer medication (odds ratio = 3.21; 95% CI, 2.66-3.88). Twenty-six percent of users switched brands. Only 9.5% of new users underwent a diagnostic procedure before initiation of therapy, and 49% of long-term users ever underwent such procedure. Despite a relatively homogeneous recommended duration of therapy, patterns of use of anti-ulcer medication among older people are highly variable, and treatment is often not accompanied by a diagnostic procedure.