Untangling the Relationship Between Medication Adherence and Post–Myocardial Infarction Outcomes: Medication Adherence and Clinical Outcomes

Study Questions:

What is the relationship between medication adherence and post–myocardial infarction (MI) adverse coronary events?

Methods:

This was a secondary analysis of the randomized MI FREEE trial. Patients who received full prescription coverage were classified as adherent (proportion of days covered ≥80%) or not based on achieved adherence in the 6 months after randomization. First major vascular event or revascularization rates were compared using multivariable Cox models adjusting for comorbidity and health-seeking behavior.

Results:

Compared with patients randomized to usual care, full coverage patients adherent to statin, beta-blocker, or angiotensin-converting enzyme inhibitor/angiotensin-receptor blocker were significantly less likely to experience the study’s primary outcome (hazard ratio [HR] range 0.64-0.81). In contrast, nonadherent patients derived no benefit (HR range 0.98-1.04, p ≤ 0.01 for the difference in HRs between adherent and nonadherent patients). Partially adherent patients had no reduction in clinical outcomes for any of the drugs evaluated, although their achieved adherence was higher than that among controls.

Conclusions:

The authors concluded that achieving high levels of adherence to each and all guideline-recommended post-MI secondary prevention medication is associated with improved event-free survival.

Perspective:

These data indicate that patients randomized to full prescription drug coverage who achieved full adherence to their prescribed secondary prevention medications had significantly better event-free survival. However, patients with more moderate levels of adherence had no protective benefit. The results highlight the importance of full adherence to post-MI secondary prevention, demonstrate that patients must adhere to all of these classes to derive maximal benefit, and provide empirical support for defining full adherence as a proportion of days covered of ≥80%. These findings underscore the importance of appropriate interventions that simplify treatment regimens, remind, and motivate patients about the importance of taking their therapies as prescribed to improve adherence and outcomes.

Clinical Topics: Dyslipidemia, Prevention, Nonstatins, Novel Agents, Statins

Keywords: Medication Adherence, Myocardial Infarction, Proportional Hazards Models, Secondary Prevention, Hydroxymethylglutaryl-CoA Reductase Inhibitors, Comorbidity, Disease-Free Survival


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