Depression and medication adherence in outpatients with coronary heart disease: findings from the Heart and Soul Study

Abstract

Background: Depression leads to adverse outcomes in patients with coronary heart disease (CHD). Medication nonadherence is a potential mechanism for the increased risk of CHD events associated with depression, but it is not known whether depression is associated with medication nonadherence in outpatients with stable CHD.

Methods: We examined the association between current major depression (assessed using the Diagnostic Interview Schedule) and self-reported medication adherence in a cross-sectional study of 940 outpatients with stable CHD.

Results: A total of 204 participants (22%) had major depression. Twenty-eight (14%) of 204 depressed participants reported not taking their medications as prescribed compared with 40 (5%) of 736 nondepressed participants (odds ratio [OR], 2.8; 95% confidence interval [CI], 1.7-4.7; P<.001). Twice as many depressed participants as nondepressed participants (18% vs 9%) reported forgetting to take their medications (OR, 2.4; 95% CI, 1.6-3.8; P<.001). Nine percent of depressed participants and 4% of nondepressed participants reported deciding to skip their medications (OR, 2.2; 95% CI, 1.2-4.2; P = .01). The relationship between depression and nonadherence persisted after adjustment for potential confounding variables, including age, ethnicity, education, social support, and measures of cardiac disease severity (OR, 2.2; 95% CI, 1.2-3.9; P = .009 for not taking medications as prescribed).

Conclusions: Depression is associated with medication nonadherence in outpatients with CHD. Medication nonadherence may contribute to adverse cardiovascular outcomes in depressed patients.

Figures

Figure 1

Proportion of participants with and without depression who were medication nonadherent.

Figure 2

Proportion of participants who were medication nonadherent according to the depression severity score on the Patient Health Questionnaire (PHQ) (P=.003 for trend). Error bars represent SD.