Do cognitive and behavioral factors mediate the impact of depression on medical outcomes in people with coronary heart disease?

PURPOSE: Depression is common in people with coronary heart disease (CHD) and predicts worse cardiac outcomes. Cognitive and behavioral mechanisms have been proposed to explain this association, although the mediating role of these mechanisms remains unclear. We conducted a prospective cohort study to investigate whether the impact of depression on subsequent impaired health-related quality of life (HRQoL) was mediated by cognitive and behavioral pathways. METHODS: Demographic and medical characteristics, depression (Hospital Anxiety and Depression Scale), illness cognitions (Brief Illness Perceptions Questionnaire and Cardiac Anxiety Questionnaire), awareness of somatic symptoms (Symptom Checklist-90, revised version), and health behaviors were recorded from 255 primary care patients with CHD. The Short Form-36 was completed by 201 participants 6 months later. RESULTS: Twenty-five participants (9.8%) were depressed at baseline. Short Form-36 Physical Component Score (PCS) was significantly lower in participants who were depressed (mean PCS score = 29.8 versus 38.0, P =.001). After controlling for demographic and medical variables, depression continued to be associated with subsequent PCS [B =-0.84(0.20), P