Objectives: An association between depression and coronary artery disease (CAD) is well established. Poor adherence to cardiac treatments may be one way depression could contribute to the increased risk of coronary events among depressed patients. We sought to evaluate whether adherence to antilipid medication, a therapy shown to be beneficial in secondary prevention of coronary events, differs among CAD patients with and without an ICD-9 depression diagnosis.
Methods: Patients were included if, at angiography, they were determined to have CAD (stenosis >or=70%), were discharged on an antilipid medication, and re-filled their prescriptions at a participating pharmacy. A patient was determined to have depression (ICD-9 codes 296.2-296.36, 311) if the diagnosis occurred prior to angiography or within 6 months of the CAD diagnosis. Adherence and long-term outcomes were evaluated at 6 months, 1 year, 18 months and 2 years.
Results: A total of 585 patients were included, with 73 (12.5%) having a diagnosis of depression prior to or within 6 months of CAD diagnosis. At all time-points, those with depression had a lower mean adherence compared to those without depression. Differences in adherence rates after adjustment were 7% (P=.001), 6% (P=.02), 13% (P<.0001) and 5% (P=.18) at 6 months, 1 year, 18 months, and 2 years, respectively. Though not statistically significant, there were clinically important associations between adherence and depression on the combined outcome of death, myocardial infarction, and revascularization.
Conclusion: Depression was the strongest predictor of antilipidemic medication adherence after 2 years of follow-up among CAD patients. Such results suggest that poor antilipid adherence may be one mechanism by which depression contributes to CAD events.
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