Ability of Low Antihypertensive Medication Adherence to Predict Statin Discontinuation and Low Statin Adherence in Patients Initiating Treatment After a Coronary Event

Abstract

Low statin adherence and discontinuation of statins are common in patients with coronary heart disease. We hypothesized that low antihypertensive medication adherence would be associated with future statin discontinuation and low adherence in patients initiating statins. Using a 5% national sample of Medicare beneficiaries, we conducted a cohort study of Medicare beneficiaries initiating statins after hospitalization for acute myocardial infarction or coronary revascularization in 2007, 2008, and 2009. Antihypertensive medication adherence, defined using the average proportion of days covered across 5 classes during the 365 days before hospitalization, was categorized as ≥80% (high), 50% to <80% (medium), and <50% (low). Statin discontinuation was defined as failure to refill a statin within 365 days of hospital discharge, and low adherence was defined as proportion of days covered for statins <80%. In 2,695 Medicare beneficiaries who initiated statins after hospital discharge, 6.0%, 8.4%, and 14.5% with high, medium, and low antihypertensive medication adherence discontinued statins. After multivariable adjustment, the risk ratios (95% confidence interval) for statin discontinuation were 1.38 (0.98 to 1.95) and 2.41 (1.51 to 3.87) for beneficiaries with medium and low versus high antihypertensive medication adherence, respectively. In beneficiaries who did not discontinue statins, 36.2% had low statin adherence. Compared with high adherence, medium and low antihypertensive medication adherences were associated with multivariable adjusted risk ratios (95% confidence interval) for low statin adherence of 1.33 (1.14 to 1.55) and 1.62 (1.25 to 2.10), respectively. In conclusion, low antihypertensive medication adherence before initiating statins is associated with future statin discontinuation and low statin adherence.