Antihypertensive drug prescribing and persistence among new elderly users: Implications for persistence improvement interventions

Background: The objective of this study was to examine persistence rates and factors influencing persistence for new elderly users of antihypertensive drugs. Methods: We conducted a population-based cohort study in Ontario of adults aged 66 years or older to identify new users of antihypertensive medications between 1999 and 2010. Two-year therapy and class persistence were defined as persistence on any antihypertensive medication and persistence only on the same antihypertensive medication class, respectively. Results: From 1999-2010, the prevalence of antihypertensive drug use increased from 47.8%-60.5% (P < 0.0001). Persistence was evaluated in 420,148 new users of antihypertensive drugs. After 2 years, therapy persistence was 58.9% and varied according to initial class prescribed, from 52.3% for diuretics to 64.1% for angiotensin-converting enzyme inhibitors. Class persistence ranged from 25.3% for diuretics to 35.8% for angiotensin II receptor blockers. Therapy persistence rates were greater in new users from more recent years (adjusted odds ratio [aOR], 1.24; 95% confidence interval [CI], 1.21-1.27). Subgroups that demonstrated poorer persistence included patients older than 75 years (aOR, 0.95; 95% CI, 0.94-0.96), those with lowest neighbourhood income quintile (aOR, 0.81; 95% CI, 0.80-0.83 compared with the highest quintile), those from urban vs rural areas (aOR, 0.83; 95% CI, 0.81-0.84), and those who started on diuretics as initial monotherapy compared with all other drug classes. Conclusions: Although 2-year therapy and class persistence were low for new users of antihypertensive drugs, improvements have occurred over the past decade. Our data highlight subgroups to target for future persistence improvement interventions.