Profile of inappropriate prescription drug use among British Columbia seniors (1991–2001)

Purpose The aim of this study was to quantify British Columbia medication utilization among seniors over 10 years (1991–2001) using the provincial Pharmacare database, with a focus on inappropriate prescription drug use. Inappropriate medications were determined using Beersʹ Explicit Criteria (Beers, 1997) for inappropriate drugs for seniors. Methods Ten years of the British Columbia prescription drugs claims database for seniors were analyzed. Complete records for all prescription drugs filled by British Columbia seniors are recorded and maintained by the PharmaNet program; only seniors in hospitals are not covered by this database. Using the American Hospital Formulary System (AHFS) therapeutic classification system, drugs defined by Beersʹ Explicit Criteria as being inappropriate for seniors were identified and their frequencies and patterns of usage defined. Results In 1991/1992, a total 5,894,085 prescriptions were filled by 420,903 seniors in BC, resulting in an average of 14.0 prescriptions per senior. In 2000/01, 8,223,200 were filled by 523,824 seniors, corresponding to an average of 15.7 prescriptions per senior. For these two time periods, 84.2% and 83.2% of seniors (respectively) filled at least one prescription. In 1991/1992, 28.1% of the senior population in BC received at least one prescription deemed inappropriate according to the Beers criteria, compared to 23.5% in 2000/2001. In 1991/92, 8.2% of all medications prescribed were inappropriate, compared to 5.9% in 2000/2001. The average number of inappropriate prescriptions per senior for those who received at least one for these two time periods was 4.1 and 3.9, respectively. The rate of inappropriate prescriptions per 100 seniors in 1991/1992 was 115.4, and 92.5 in 2000/2001. Conclusion This study suggests that inappropriate medications are prescribed at significant levels to BC seniors. Although there was a decrease in the mid-90s, inappropriate prescribing is once again on the rise. Further investigation is needed to explain the decrease and subsequent rise.