Donepezil Adherence, Persistence and Time to First Discontinuation in a Three-Year Follow-Up of Older People

BACKGROUND Donepezil is indicated for the management of mild to moderate dementia, particularly in Alzheimer's disease. Several studies have described low adherence rates with donepezil. AIM To examine and measure donepezil adherence, persistence and time to first discontinuation in older New Zealanders. METHODS An inception cohort of 1,999 new users of donepezil, aged 65 years or older, were identified from the Pharmaceutical Collections and National Minimum Dataset from 1 November 2010 to 31 December 2013. Kaplan-Meier curves and Cox regression analysis were used to estimate the cumulative probability and risk of time to first discontinuation of donepezil therapy. RESULTS The mean age of the cohort was 79.5 ± 6.4 years and included 42.7% females. Adherence was high (89.0%), while the proportion of donepezil dispensings (81.0-32.5%) declined between 6 and 36 months. Persistence between the 1st and 6th dispensing visit decreased by 19.0%, and 11.0% of the total cohort had a gap of 31 days or more. The adjusted risk of time to first discontinuation in the non-adherent group was 2.2 times (95% CI 1.9-2.6) that of the adherent group. CONCLUSIONS The non-adherent new donepezil users, on average, discontinued faster than the adherent group. Time to first discontinuation in this study was higher compared to discontinuation rates observed in clinical trials.