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.