Interaction of Depressive and Anxiety Symptoms on the Mortality of Patients with COPD: A Preliminary Study

AbstractBackground: Depressive and anxiety symptoms increase the risk of death in patients with Chronic Obstructive Pulmonary Disease (COPD), but the combined effects of the two factors are unknown. Purpose: To assess the possible interactive effects of depressive and anxiety symptoms on the death of patients with COPD. Methods: Prospective data for 7787 Chinese patients with COPD was analyzed and the deaths were recorded. Depressive and anxiety symptoms were evaluated using the Hospital Anxiety and Depression Scale. A product of depressive and anxiety symptoms was added to the logistic regression model to evaluate the multiplicative interaction, and relative excess risk of interaction (RERI), attributable proportion (AP) of interaction, and synergy index (S) were applied to evaluate the additive interaction of the two factors. Bootstrap was used to calculate 95% confidence intervals (CIs) of RERI, AP and S. RERI > 0, AP > 0, or S > 1 indicated biological interaction. Results: After 4 years’ follow-up, th...