Objective: Recent research demonstrates that depression experienced around the time of a cardiac event predicts mortality over subsequent years. However, few studies have differentiated between ‘mild’ and ‘moderate/severe’ depression. We investigated the prognostic importance of mild and moderate/severe in-hospital depression in predicting mortality over 12 years in female cardiac patients.

Methods: A consecutive sample of 170 women admitted to three Melbourne hospitals following either acute myocardial infarction or coronary artery bypass graft surgery completed the Hospital Anxiety and Depression Scale (HADS) during hospitalisation for their cardiac event. HADS scores were classified using two cut-points defined specifically for cardiac patients: 4-7 (mild depressive symptoms) and 8+ (moderate/severe depressive symptoms). Sociodemographic data were collected by interview and self-report questionnaire. Medical data were collected from hospital medical records. Mortality was tracked through the Australian National Death Index and other sources.

Results: In hospital, 38% women had mild depressive symptoms, while 20% had moderate/severe depressive symptoms. Over the 12 year follow-up period, 58 (34%) women died. Using logistic regression, and controlling for age and disease severity, mild in-hospital depression was significantly associated with mortality (p=.013) whereas moderate/severe in-hospital depression was not (p=.112). Age and diabetes status were also significantly associated with death. Survival analysis confirmed this pattern of results.

Conclusions: Mild in-hospital depression was more predictive of mortality than was moderate/severe in-hospital depression. These findings highlight the predictive value of even mild depressive symptoms, and have important implications for in-hospital depression screening and management.