Abstract P173: Improvements in Adherence to Antihypertensive Medication Among Medicare Beneficiaries Initiating Treatment Between 2007 and 2012

Abstract

Introduction: Low antihypertensive medication adherence has been reported, leading to recommendations for interventions to improve adherence. We evaluated trends in low medication adherence and discontinuation among Medicare beneficiaries initiating antihypertensive medication from 2007 to 2012. Hypothesis: Low antihypertensive medication adherence has decreased over time. Methods: We analyzed data on beneficiaries with ≥ 2 diagnoses for hypertension (ICD-9, 401.xx) in the Medicare 5% random sample initiating antihypertensive medication. Initiation was defined by a pharmacy claim for antihypertensive medication with no claims within the previous 365 days. Beneficiaries were required to have full Medicare fee-for-service coverage (Parts A, B and D) for the 365 days prior to and following the date of initiation. Low adherence was defined as having a proportion of days covered <80% during the 365 day following initiation. Discontinuation was defined as having no days of supply or fills during the final 73 days in the year following initiation. Results: Between 2007-2012, 44,147 Medicare beneficiaries initiated antihypertensive medication. In the overall sample, low adherence decreased from 36.4% in 2007 to 31.7% in 2012 (p<0.001) (Table). After multivariable adjustment, the relative risk (RR) of low adherence for beneficiaries initiating treatment in 2012 compared with those initiating treatment in 2007 was 0.84 (95% CI 0.79-0.89). Throughout the study period, low adherence was more common in beneficiaries that were black (RR 1.41; 95% CI 1.35-1.48), Hispanic (RR 1.40; 95% CI 1.30-1.50), had low income (RR 1.19; 95% CI 1.08-1.32), depression (RR 1.06; 95% CI 1.01-1.12), or a serious fall injury following antihypertensive medication initiation (RR 1.34; 95% CI 1.23-1.47). Discontinuation did not decrease over time. Conclusion: Low adherence to antihypertensive medication among Medicare beneficiaries has decreased over time. Higher rates of low adherence remain for blacks compared with whites.