Appropriateness of omeprazole prescribing in Quebec's senior population

BACKGROUND: Prescribing omeprazole for the treatment of digestive disorders accounts for an important part of the costs in Quebec's drug benefit plan. In July 1993, the Quebec drug program listed omeprazole, with restriction, in its formulary. On January 1, 1994, this restriction was lifted; since t hen, omeprazole has been listed in the regular provincial formulary. OBJECTIVE: To describe the appropriateness of initial omeprazole prescribin g in the ambulatory senior population of Quebec in the 27 months after bein g listed without restriction. SUBJECTS AND METHODS: A retrospective population-based cohort study was per formed using prescription and medical services claims databases of the Queb ec drug program. Data were extracted for elderly patients who received thei r first omeprazole prescription between July 1, 1994 and March 31, 1996. RESULTS: Among the 47,140 first-time users of omeprazole identified, 7516 ( 15.9%) had had an endoscopy in the previous six months, 2308 (49%) were giv en an antimicrobial agent and omeprazole simultaneously, and 22,730 (48.2%) received omeprazole after prior use of an HZ receptor antagonist (H2RA) or a prokinetic drug. A total of 26,525 (56.3%) first-time users were prescri bed omeprazole based on at least one of the three criteria listed above. Am ong these users, 729 (2.8%) received an H2RA concurrently with omeprazole. Altogether, 25,796 (54.7%) first-time users received omeprazole appropriate ly. CONCLUSIONS: Although reimbursement for omeprazole prescriptions has not be en restricted in Quebec since January 1, 1994, it was prescribed appropriat ely for elderly patients in the majority of cases studied.