Appropriateness of omeprazole prescribing in Quebec's senior population

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 then, omeprazole has been listed in the regular provincial formulary.

To describe the appropriateness of initial omeprazole prescribing in the ambulatory senior population of Quebec in the 27 months after being listed without restriction.

A retrospective population-based cohort study was performed using prescription and medical services claims databases of the Quebec drug program. Data were extracted for elderly patients who received their first omeprazole prescription between July 1, 1994 and March 31, 1996.

Among the 47,140 first-time users of omeprazole identified, 7516 (15.9%) had had an endoscopy in the previous six months, 2308 (4.9%) were given an antimicrobial agent and omeprazole simultaneously, and 22,730 (48.2%) received omeprazole after prior use of an H2 receptor antagonist (H2RA) or a prokinetic drug. A total of 26,525 (56.3%) first-time users were prescribed omeprazole based on at least one of the three criteria listed above. Among these users, 729 (2.8%) received an H2RA concurrently with omeprazole. Altogether, 25,796 (54.7%) first-time users received omeprazole appropriately.

Although reimbursement for omeprazole prescriptions has not been restricted in Quebec since January 1, 1994, it was prescribed appropriately for elderly patients in the majority of cases studied.