Symptoms of depression are strongly linked to cardiovascular events, and Whooley and colleagues examined this relationship in outpatients with stable coronary heart disease. This prospective cohort study analyzed the association of depressive symptoms and cardiovascular events in 1,017 patients followed for a mean of 4.8 years.

According to scores on the Patient Health Questionnaire, 199 of the 1,017 patients had depressive symptoms. These 199 patients were more likely than the other patients to smoke, be less physically active, have a higher mean body mass index, and be less compliant with medications. The annual rate of cardiovascular events in patients with depressive symptoms was 10%, compared with 6.7% in the group without these symptoms. The depressive symptom group had a 50% greater chance of experiencing a cardiovascular event than the group without depressive symptoms; after adjusting for comorbid conditions and severity of heart disease, this rate decreased to 31%. The authors noted a direct relationship between higher depressive symptom scores and cardiovascular events.

After adjusting for depressive symptoms and other factors, physical inactivity increased the risk of a cardiac event by 44%. Also, some patients didn't have major depressive disorder as defined by the Diagnostic and Statistical Manual of Mental Disorders, 4th edition, yet they had high scores for depressive symptoms because they frequently experienced symptoms. The authors suggest that, compared with meeting major depressive disorder criteria, a high frequency of depressive symptoms may be a stronger indicator of physical inactivity and, in turn, cardiovascular events. Thus, increasing physical activity and decreasing depressive symptoms may reduce the risk of cardiovascular events in patients with a history of heart disease.

Whooley MA, et al. JAMA 2008;300(20): 2379-88.