Long-term persistence and adherence to blood pressure lowering agents among older Australians

Purpose: Poor adherence and persistence to blood pressure lowering (BPL) agents leads to increased risk of morbidity and mortality. The aim of this study was to investigate the long-term adherence, persistence, and re-initiation of BPL agents among older Australians (aged ≥65 years). Methods: We utilised the Pharmaceutical Benefits Scheme data covering a 10% random sample of Australians. We identified 31 088 older Australians (mean age, 75.4 years; 56% females) with newly initiated BPL therapy from 2008 to 2016. Adherence was assessed using the proportion of days covered (PDC) at 6-month intervals. Discontinuation was defined as ≥90 days without BPL coverage. Cox regression was applied to compare the time till the first discontinuation of BPL agents across different BPL categories and among various subgroups. Results: Over a mean follow-up of 3.8 years, 40% to 70% of older Australians received a BPL agent discontinued it. The median time to discontinuation ranged from 159 to 373 days. Persistence with fixed dose combinations was the best (68%, 58%, and 41% at 6, 12, and 36 months respectively), followed by angiotensin II receptor blockers (69%, 58%, and 40%), beta-blockers (67%, 54%, and 36%), angiotensin converting enzyme inhibitors (62%, 51%, and 34%), calcium channel blockers (57%, 47%, and 31%), and diuretics (59%, 41%, and 23%). Among those who discontinued, 30% to 50% re-initiated, with median days to re-initiation ranging from 177 to 302. Only 21% to 42% of the study population maintained “good” adherence (PDC ≥ 0.8) to BPLs over 3 years. Conclusion: Compliance to BPL agents is poor among older Australians. Interventions to enhance adherence and persistence to BPL agents are needed.