Major depression is one of the risk factors identified for increased morbidity and mortality in patients with coronary heart disease (CHD). Recently, psychological factors were found to be one of the modifiable risk factors for myocardial infarction. Several biological mechanisms could account for the increased risk of CHD events in patients with depression. However, one factor that has not been well researched is whether patients with depression are less likely to participate in cardiac prevention and treatment regimens. With other diseases, depression has been shown to decrease patients’ compliance with medication regimens. Gehi and associates assessed the effect of depression on adherence to treatment regimens in patients with CHD in the outpatient setting.

This cohort study was multicentered and included outpatients with known stable CHD. All of the participants received a baseline examination that included being assessed for major depression using a computerized interview and the nine-item Patient Health Questionnaire. The participants were divided into three groups based on survey results: none or minimal, mild to moderate, or severe depressive symptoms. Overall medication adherence was assessed by the following questions: (1) “In the past month, how often did you take your medications as the doctor prescribed?”; (2) “In the past month, how often did you forget to take one or more of your prescribed medications?”; (3) “In the past month, how often did you decide to skip one or more of your prescribed medications?”

There were 940 participants who met the inclusion criteria and completed the study. Of these participants, 22 percent were categorized as having major depression. Fourteen percent of depressed participants recounted that they were not taking their medications compared with 5 percent of those without major depression. The odds ratio for depressed patients not adhering to their medication regimen was 2.8 (95% confidence interval, 1.7 to 4.7). When compared with those without major depression, twice as many of the depressed patients forgot to take their medications. In addition, a significant number of depressed participants reported that they decided to skip their medication. When compounding variables were controlled in the data analysis, participants with depression were significantly more likely to be nonadherent to their medication regimens.

The authors concluded that patients with stable CHD and depression were less likely to adhere to their medication regimens. They add that this may be a factor in the increased risk of poor cardiovascular outcomes in depressed patients with CHD.