Depressive symptoms and survival of patients with coronary artery disease.

OBJECTIVE: Multiple studies have shown that high levels of depressive symptoms increase the mortality risk of patients with established coronary disease. This investigation divided depressive symptoms into groups to assess their relative effectiveness in predicting survival.
METHODS: Questionnaires about the presence of depressive symptoms were administered to 1250 patients with significant coronary disease while they were hospitalized for diagnostic coronary angiography. Follow-up for mortality due to cardiac disease was conducted annually for up to 19.4 years. Factor analysis was used to divide items on the Zung Self-Rating Depression Scale into four groups: Well-Being, Negative Affect, Somatic, and Appetite. In addition, responses to a single item regarding feelings of hopelessness were available for 920 patients.
RESULTS: Well-Being and Somatic symptoms significantly predicted survival (p < or = .01). Negative Affect items were also related to survival (p = .0001) and interacted with age. A 2-SD difference in the Negative Affect term was associated with a relative risk of 1.29 for patients >50 years old and 1.70 for younger ones. Only Negative Affect remained significant in a model with the other symptom groups. Hopelessness also predicted survival with a relative risk of 1.5. Both the Hopelessness and Negative Affect items remained as independent predictors in the same model. All models controlled for severity of disease and treatment. With one exception (income and Hopelessness), results were essentially unchanged by additional controls for age, gender, and income.
CONCLUSIONS: Depressive symptoms differentially predicted survival, with depressive affect and hopelessness being particularly important. These effects were independent of disease severity and somatic symptoms and may be especially important in younger patients.