Depression and self-reported physical health in patients with coronary disease: mediating and moderating factors.

OBJECTIVES: The purpose of this study was to define how the relation between depression and self-reported physical health in patients with coronary disease is modified by other patient-centered factors.
METHODS: We conducted a prospective cohort study of 111 patients (members of a health maintenance organization) with angiographically documented coronary disease, examining factors (physical symptoms, psychological states and traits, and spousal support) modifying the relation between depression and patient-reported physical health 5 years later using multiple hierarchical regression models.
RESULTS: Five regression models (all including demographic and disease severity covariates) were constructed to predict physical health from depression only (R2 = 0.22); depression plus angina and fatigue (R2 = 0.53); depression plus positive affect and novelty seeking and their interaction (R2 = 0.48); depression plus spousal support (R2 = 0.27); and depression, angina, fatigue, positive affect, and novelty seeking (overall model) (R2 = 0.65). Depression remained significant in each model, but the proportion of variance it predicted was diminished in the presence of the other variables (bivariate r = 0.39, partial r = 0.37-0.13).
CONCLUSIONS: The effect of depression on self-reported physical health is significantly mediated by physical symptoms (angina and fatigue), personality states and traits (positive affect and novelty seeking), and spousal support. Positive affect and novelty seeking had more marked effects on physical health in the presence of more depression. Thus, a broad range of factors beyond the severity of coronary disease itself affect the perceived physical health of patients with coronary heart disease.