Compliance, Persistence, and Switching Patterns for ACE Inhibitors and ARBs

Objectives: To investigate compliance, persistence, and switching patterns for angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs). Study Design: Drug-utilization analysis using a large prescription database. Methods: Prescription data for more than 50,000 incident users of ACE inhibitors or ARBs were collected, cumulating close to 200,000 patient-years of medication use. Incidence, drug dosage, 1-year compliance, long-term persistence, and switching patterns were analyzed. The specific drugs investigated were captopril, enalapril, lisinopril, perindopril, ramipril, and fosinopril (ACE inhibitors), and losartan, valsartan, irbesartan, candesartan, and olmesartan (ARBs). Results were adjusted for age, sex, starting date, and comorbidities. Results: The 1-year compliance (88.3% vs 88.3%, P = .996) and 3-year persistence (81.9% vs 82.4%, P = .197) rates were similar between ACE inhibitors and ARBs. Users of ACE inhibitors more often switched therapy (24.2% vs 13.1%, P < .001), primarily to an ARB. Variations in compliance, persistence, and switching behavior were detected between specific ACE inhibitors, but not between specific ARBs. Conclusions: Although residual confounding and indication bias cannot be ruled out, this study showed that compliance, persistence, and switching behavior varied between specific ACE inhibitors but not between specific ARBs. These results support prescribing of cheap generic ARBs as opposed to expensive ARBs. Apart from factors leading to therapy switches, compliance and persistence were similar between ACE inhibitors and ARBs. (Am J Manag Care. 2011; 17(9): 609-616)