PURPOSE: To determine the rates of patient adherence to key evidence-based therapies at 6 months after hospital discharge for an acute coronary syndrome.

METHODS: In this nonrandomized, prospective, multinational, multicenter study, adherence to aspirin, beta-blockers, statins, or angiotensin-converting enzyme (ACE) inhibitors 6 months after discharge for myocardial infarction or unstable angina was assessed in 21,408 patients aged 18 years or older. Patients were enrolled at 104 tertiary and community hospitals representing a broad range of care facilities and practice settings (e.g., teaching vs. nonteaching).

RESULTS: Of 13,830 patients, discontinuation of therapy was observed at 6-month follow-up in 8% of those taking aspirin on discharge, 12% of those taking beta-blockers, 20% of those taking ACE inhibitors, and 13% of those taking statins. In a multivariate analysis, adherence to beta-blocker therapy was higher in patients with a myocardial infarction (odds ratio [OR] = 1.25; 95% confidence interval [CI]: 1.06 to 1.47), hypertension (OR = 1.33; 95% CI: 1.15 to 1.54), ST-segment elevation myocardial infarction (OR = 1.33; 95% CI: 1.11 to 1.61), or non-ST-segment elevation myocardial infarction (OR = 1.25; 95% CI: 1.08 to 1.45). Aspirin adherence was higher among patients cared for by cardiologists (OR = 1.45; 95% CI: 1.19 to 1.75; P <0.001) than among those cared for by nonspecialists. Male sex and prior heart failure were associated with improved adherence to ACE inhibitor therapy. Hypertension was associated with poorer adherence to statin therapy (OR = 0.85; 95% CI: 0.74 to 0.99; P = 0.04).

CONCLUSION: Among patients prescribed key evidence-based medications at discharge, 8% to 20% were no longer taking their medication after 6 months. The reasons for noncompliance are complex, and may be elucidated by future studies of medical and social determinants.