National evaluation of adherence to β-blocker therapy for 1 year after acute myocardial infarction in patients with commercial health insurance

Background Quality measures of evidence-based medications post–myocardial infarction have focused on prescription at hospital discharge. Yet survival benefits of these medications are best realized with sustained therapy. We sought to examine long-term β-blocker adherence over the first year after myocardial infarction in patients with commercial health insurance and prescription drug benefits. Methods This multicenter analysis examined health plan records from members of 11 health plans who had myocardial infarction in 2001, survived at least 1 year, and maintained insurance coverage (N = 17 035). The primary outcome measure was adherence to β-blockers (defined as prescription claims covering ≥75% of days) for 360 days post-discharge. We also examined associations with adherence—time from discharge, health plan product (commercial or Medicare + Choice [M + C]), age (35-64 or ≥65), sex, and region. Results For 360 days after discharge, only 45% of patients were adherent to β-blockers, with the biggest drop in adherence between 30 and 90 days. In a multivariable model, statistically significant predictors of lower adherence were participation in M + C product, residence in the Southeast, and age (driven by young participants in M + C and young females in commercial products). Conclusions In a population of patients with health insurance and prescription drug coverage, adherence to β-blocker therapy in the first year after myocardial infarction is poor, indicating that factors other than medication cost are important determinants of long-term adherence. Quality improvement initiatives focused on long-term adherence are needed to realize maximal benefit from medical therapy in post–myocardial infarction patients.