Antihypertensive and Statin Medication Adherence Among Medicare Beneficiaries

Abstract

Medication adherence is important for optimal management of chronic conditions, including hypertension and hypercholesterolemia. This study describes adherence to antihypertensive and statin medications, individually and collectively, and examines variation in adherence by demographic and geographic characteristics. The 2017 prescription drug event data for beneficiaries with Medicare Part D coverage were assessed. Beneficiaries with a proportion of days covered ≥80% were considered adherent. Adjusted prevalence ratios were estimated to quantify the associations between demographic and geographic characteristics and adherence. Adherence estimates were mapped by county of residence using a spatial empirical Bayesian smoothing technique to enhance stability. Analyses were conducted in 2019‒2021. Among the 22.5 million beneficiaries prescribed antihypertensive medications, 77.1% were adherent; among the 16.1 million prescribed statin medications, 81.9% were adherent; and among the 13.5 million prescribed antihypertensive and statin medications, 70.3% were adherent to both. Adherence varied by race/ethnicity: American Indian/Alaska Native (adjusted prevalence ratio=0.83, 95% confidence limit=0.82, 0.842), Hispanic (adjusted prevalence ratio=0.90, 95% confidence limit=0.90, 0.91), and non-Hispanic Black (adjusted prevalence ratio=0.87, 95% confidence limit=0.86, 0.87) beneficiaries were less likely to be adherent than non-Hispanic White beneficiaries. County-level adherence ranged across the U.S. from 25.7% to 88.5% for antihypertensive medications, from 36.0% to 93.8% for statin medications, and from 20.8% to 92.9% for both medications combined and tended to be the lowest in the southern U.S. This study highlights opportunities for efforts to remove barriers and support medication adherence, especially among racial/ethnic minority groups and within the regions at greatest risk for adverse cardiovascular outcomes.