Extent and variation of omeprazole prescribing in an elderly population of Ontario

Abstract

Objective: To determine the extent of omeprazole prescribing in the senior population of Ontario over a 1-year period; the variation in omeprazole prescribing for this population according to age group, gender, and geographic region: and the extent of inappropriate prescribing of omeprazole for this population.

Design: Retrospective drug utilization review of prescription drug insurance claims.

Data source: The Ontario Drug Benefit (ODB) program claims database.

Outcome measures: The following outcomes were measured: the proportion of seniors in Ontario who received a prescription for omeprazole from April 1, 1992 to March 31, 1993: effects of age group, gender, and geographic region of residence on omeprazole prescribing; and the extent of inappropriate omeprazole prescribing according to the ODB criteria for use. Prescribing of omeprazole was defined as inappropriate if a first-line antiulcer drug (i.e., histamine2-receptor antagonist) was not prescribed within 1-6 months of the first prescription claim for omeprazole.

Results: A total of 29,936 seniors in Ontario received omeprazole from April 1, 1992 to March 31, 1993 (2.53 recipients per 100 eligible population). The age-gender group most frequently prescribed omeprazole was women 65-74 years, followed by women and men 75 years or older, and then men 65-74 years. Omeprazole prescribing varied widely among the 48 provincial counties (range of 1.66 recipients per 100 eligible population to 4.52 recipients per 100 population, p < 0.001). There was no evidence of a clustering effect in omeprazole prescribing at the county level. Prescribing of omeprazole was considered to be inappropriate for 80.5% of recipients.

Conclusions: This study demonstrated the ineffectiveness of the ODB limited-use program in controlling omeprazole prescribing. Further study should be done to examine determinants of variation in prescribing by geographic region.