Association of Patient Enrollment in Medicare Part D with Outcomes after Acute Myocardial Infarction

Background-Little is known about whether enrollment versus nonenrollment in Medicare's prescription drug plan (Part D) is associated with better outcomes after acute myocardial infarction (AMI). Methods and Results-Using Medicare records linked to Acute Coronary Treatment and Intervention Outcomes Network Registry-Get With The Guidelines, we identified 59 149 Medicare beneficiaries (age ≥65 years) discharged after AMI between January 2007 and December 2010. We described trends in Medicare Part D enrollment, and compared the following 30-day and 1-year outcomes: All-cause death, all-cause readmissions, and major adverse cardiac events (a composite of all-cause death or readmission for AMI or stroke) between Part D enrollees and nonenrollees, after adjustment for patient and hospital factors. From 2007 to 2010, 29 264 (49.5%) patients with AMI enrolled in Medicare were also participating in Part D by hospital discharge. All-cause 30-day death was more common among enrollees versus nonenrollees (4.0% versus 3.3%), but this difference was not statistically significant after multivariable adjustment (adjusted hazard ratio, 1.06 [95% confidence interval, 0.97-1.17]). Enrollees also had higher unadjusted risks of 30-day all-cause readmissions or major adverse cardiac events, and 1-year mortality, all-cause readmissions, or major adverse cardiac events, but these were attenuated after multivariable adjustment. Adherence to key secondary prevention medications (statins, β-blockers, angiotensin-converting enzyme inhibitors or angiotensin receptor blockers, and P2Y12 antagonists) remained low (range, 55%-64%) at 1 year post discharge among Part D enrollees. Conclusions-Only half of Medicare-insured patients with AMI were enrolled in Part D by hospital discharge, and their 30-day and 1-year adjusted outcomes did not differ substantially from nonenrollees. There remain opportunities for improvement in medication adherence among patients with prescription drug coverage.