Treatment, outcomes, and adherence to medication regimens among dual Medicare-Medicaid–eligible adults with myocardial infarction

IMPORTANCE: Patients with dual Medicare-Medicaid eligibility have a higher burden of chronic disease conditions and increased health care utilization compared with patients with Medicare coverage alone, but the treatment patterns and outcomes of dual-eligible patients with myocardial infarction (MI) are unknown. OBJECTIVE: To examine the association of dual-eligible status with clinical outcomes and adherence to medication regimens (hereinafter “medication adherence”) among older adults after MI. DESIGN, SETTING, AND PARTICIPANTS: In this retrospective study conducted from February 2015 to April 2016, we linked patients 65 years or older enrolled in a national myocardial infarction registry (the Acute Coronary Treatment Intervention Outcomes Network Registry–Get With the Guidelines [ACTION Registry-GWTG]) from July 1, 2007, to December 31, 2009, to Medicare claims data to obtain 1-year follow-up and medication adherence data. The ACTION Registry-GWTG is the largest quality-improvement registry of patients with MI in the United States. Included patients were all 65 years or older; had Medicare Parts A, B, and D; presented with MI; and survived to hospital discharge. EXPOSURES Dual Medicare and Medicaid eligibility. MAIN OUTCOMES AND MEASURES: Death, readmission, major adverse cardiovascular events (death, recurrent MI, stroke), and medication adherence at 1 year. RESULTS: Of 17 419 Medicare patients discharged alive after MI, 4674 (27%) were dual eligible. Dual-eligible patients were more likely to be female (64% vs 49%) and nonwhite (29% vs 6%), with a higher prevalence of comorbid conditions and more frequent presentation with non-ST elevation MI (non-STEMI) (75% vs 69%). Dual-eligible patients were less likely to receive primary percutaneous coronary intervention for STEMI (77% vs 81%), revascularization for non-STEMI (58% vs 65%), and prescription of secondary prevention medications at discharge. After multivariable adjustment, dual eligibility status was associated with a higher risk of readmission at 30 days (hazard ratio [HR], 1.16; 95% CI, 1.06-1.26), death at 1 year (HR, 1.24; 95% CI, 1.14-1.36), and major adverse cardiac events at 1 year (HR, 1.21; 95% CI, 1.12-1.31). Dual-eligible patients had higher 1-year adherence to medications prescribed at discharge (HR, 1.55; 95% CI, 1.39-1.74) than Medicare-only patients. CONCLUSIONS AND RELEVANCE: Compared with Medicare-only patients, older adults with dual Medicare-Medicaid eligibility presenting with MI have superior rates of medication adherence but higher rates of postdischarge readmission and adverse cardiovascular outcomes.