Long-term persistence to mono and combination therapies with angiotensin converting enzymes and angiotensin II receptor blockers in Australia.

Abstract

The purpose of this study was to compare the impact of initial antihypertensive therapy including angiotensin converting enzyme inhibitors (ACE) or angiotensin II receptor blockers (ARB) on long-term persistence to therapy. A retrospective cohort study using prescription claims data from the Australian Pharmaceutical Benefit Scheme (PBS). Kaplan-Meier analysis of prescription refills and cox proportional hazard models were used to compare the time on therapy (persistence) in people newly initiated to monotherapy or combination therapy including ACE or ARB, between April 2007 and March 2008. Differences in persistence to initial drug class or any antihypertensive therapy were reported at 4-year follow-up. About 119,500 persons initiated ACE or ARB: 47% initiated ACE monotherapy; 32% ARB monotherapy; 13% ACE combinations; and 8% ARB combinations. Persistence (% on treatment at 4years) to index therapy was lower in people starting ACE and ARB combinations compared to ACE or ARB monotherapies: ACE combination (12%) versus ACE monotherapy (25%) and ARB combinations (22%) versus ARB monotherapy (35%). Persistence was higher in those initiating fixed dose combinations (FDC) versus separate pill combinations of ACEs (19 vs. 10%) and ARBs (25 vs. 14%). Persistence at 4years to any antihypertensive therapy was similar between initiators to ACE or ARB monotherapy (60 and 61%, p=0.08), ACE or ARB combinations (56%, p=0.99), and was slightly higher for separate pill combinations (57-59%) versus FDC (55%). Choice of initial antihypertensive may have little impact on long-term persistence to therapy.