Adherence Tradeoff to Multiple Preventive Therapies and All-Cause Mortality After Acute Myocardial Infarction

Abstract

Background: Angiotensin-converting enzyme (ACE) inhibitors/angiotensin II receptor blockers (ARB), beta-blockers and statins are recommended after acute myocardial infarction (AMI). Patients may adhere to some, but not all, therapies.

Objectives: The authors investigated the effect of tradeoffs in adherence to ACE inhibitors/ARBs, beta-blockers, and statins on survival among older people after AMI.

Methods: The authors identified 90,869 Medicare beneficiaries ≥65 years of age who had prescriptions for ACE inhibitors/ARBs, beta-blockers, and statins, and survived ≥180 days after AMI hospitalization in 2008 to 2010. Adherence was measured by proportion of days covered (PDC) during 180 days following hospital discharge. Mortality follow-up extended up to 18 months after this period. The authors used Cox proportional hazards models to estimate hazard ratios of mortality for groups adherent to 2, 1, or none of the therapies versus group adherent to all 3 therapies.

Results: Only 49% of the patients adhered (PDC ≥80%) to all 3 therapies. Compared with being adherent to all 3 therapies, multivariable-adjusted hazard ratios (95% confidence intervals [CIs]) for mortality were 1.12 (95% CI: 1.04 to 1.21) for being adherent to ACE inhibitors/ARBs and beta-blockers only, 0.98 (95% CI: 0.91 to 1.07) for ACEI/ARBs and statins only, 1.17 (95% CI: 1.10 to 1.25) beta-blockers and statins only, 1.19 (95% CI: 1.07 to 1.32) for ACE inhibitors/ARBs only, 1.32 (95% CI: 1.21 to 1.44) for beta-blockers only, 1.26 (95% CI: 1.15 to 1.38) statins only, and 1.65 (95% CI: 1.54 to 1.76) for being nonadherent (PDC <80%) to all 3 therapies.

Conclusions: Patients adherent to ACE inhibitors/ARBs and statins only had similar mortality rates as those adherent to all 3 therapies, suggesting limited additional benefit for beta-blockers in patients who were adherent to statins and ACE inhibitors/ARBs. Nonadherence to ACE inhibitors/ARBs and/or statins was associated with higher mortality.

Keywords: medication adherence; myocardial infarction; older adults; secondary prevention.

Figure 1. Flow chart of the study population

ACEI/ARB = angiotensin converting enzyme inhibitors/angiotensin II receptor blockers; AMI = acute myocardial infarction.

Figure 2. Crude and adjusted rates and hazard ratios (95% confidence intervals) of all-cause mortality by adherence categories to preventive therapies in the whole study cohort

ACEI/ARB = angiotensin converting enzyme inhibitors/angiotensin II receptor blockers; K-M, Kaplan-Meier. Reference group: patients who were adherent to all 3 preventive therapies. Hazard ratios are adjusted for patient characteristics shown in Online Table 1.

Figure 3. Hazard ratios (95% confidence intervals) of all-cause mortality by adherence to various combinations of preventive therapies in subgroups stratified by presence heart failure, diabetes, and dementia and age and sex

Reference group: patients who were adherent to all 3 preventive therapies. Hazard ratios are adjusted for patient characteristics shown in Online Table 1 and total intensive care unit and inpatient days. ACEI/ARB = angiotensin converting enzyme inhibitors/angiotensin II receptor blockers.

Central Illustration. Adherence trade-off to preventive therapies and survival

Adjusted survival curves and hazard ratios (95% confidence intervals) of all-cause mortality by adherence categories to preventive therapies. ACEI/ARB = angiotensin converting enzyme inhibitors/angiotensin II receptor blockers; CI = confidence interval; HR = hazard ratio. Reference group: patients who were adherent to all 3 preventive therapies. Hazard ratios are adjusted for patient characteristics shown in Online Table 1.