Clinical Investigation
Coronary Artery Disease
Medication nonadherence is associated with a broad range of adverse outcomes in patients with coronary artery disease

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Background

Little is known about the effect of nonadherence among patients with coronary artery disease (CAD) on a broad spectrum of outcomes including cardiovascular mortality, cardiovascular hospitalizations, and revascularization procedures.

Methods

This was a retrospective cohort study of 15 767 patients with CAD. Medication adherence was calculated as proportion of days covered for filled prescriptions of β-blockers, angiotensin-converting enzyme (ACE) inhibitors, and statin medications. Multivariable Cox regression assessed the association between medication nonadherence as a time-varying covariate and a broad range of outcomes, adjusting for demographics and clinical characteristics. Median follow-up was 4.1 years.

Results

Rates of medication nonadherence were 28.8% for β-blockers, 21.6% for ACE inhibitors, and 26.0% for statins. In unadjusted analysis, nonadherence to each class of medication was associated with higher all-cause and cardiovascular mortality. In multivariable analysis, nonadherence remained significantly associated with increased all-cause mortality risk for β-blockers (hazard ratio [HR] 1.50, 95% CI 1.33-1.71), ACE inhibitors (HR 1.74, 95% CI 1.52-1.98), and statins (HR 1.85, 95% CI 1.63-2.09). In addition, nonadherence remained significantly associated with higher risk of cardiovascular mortality for β-blockers (HR 1.53, 95% CI 1.16-2.01), ACE inhibitors (HR 1.66, 95% CI 1.26-2.20), and statins (HR 1.62, 95% CI 1.124-2.13). The findings of increased risk associated with nonadherence were consistent for cardiovascular hospitalization and revascularization procedures.

Conclusions

Nonadherence to cardioprotective medications is common in clinical practice and associated with a broad range of adverse outcomes. These findings suggest that medication nonadherence should be a target for quality improvement interventions to maximize the outcomes of patients with CAD.

Section snippets

Study setting

Kaiser Permanente of Colorado (KPCO) is an integrated nonprofit Managed Care Organization that provides medical services to more than 430 000 members in the Denver, CO, metropolitan area. A CAD registry was previously established in 1998.10 Patients are identified by an algorithm applied to KPCO automated databases consisting of hospitalization records and outpatient diagnoses. Once a potential patient is identified, the diagnosis of CAD is validated by chart review before inclusion in the

Results

Baseline characteristics of adherent and nonadherent patients for each class of medication are shown in Table I. Among patients dispensed β-blockers (n = 11 865), 28.8% of the patients were nonadherent, as defined by a PDC <0.80. For patients dispensed ACE inhibitors or angiotensin receptor blocker (ACE inhibitors) medications (n = 10 021), 21.6% of patients were nonadherent. For statin medications (n = 13 596), 26.0% of the patients were nonadherent. Across the 3 classes of medications,

Discussion

The objective of this study was to assess the association between medication nonadherence and a broad range of outcomes among patients with known CAD in the outpatient setting. Over a median follow-up of 4.1 years, we found that medication nonadherence to statins, ACE inhibitors, or β-blockers was common, with about 1 in 4 patients being nonadherent to their prescribed β-blockers, statins, and/or ACE inhibitors. Medication nonadherence was associated with significantly increased risk for

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  • Cited by (0)

    This work was supported by an award from the American Heart Association (0535086N). Dr Ho is supported by a VA Research and Development Career Development Award (05-026-2). Dr Peterson is supported by an award from the American Heart Association (0670017N).

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