Depression and chronic obstructive pulmonary disease (COPD). Impact on survival

OBJECTIVE: To determine if the presence of depression in patients suffering from chronic obstructive pulmonary disease (COPD) would have an independent impact on mortality. METHOD: Prospective evaluation of the impact of depression according to the ICD-10 criteria for depression. Cox proportional hazards regression was used to evaluate the independent impact of depression after controlling for significant univariate clinical predictors in the data set. Consenting out-patients (n = 49) who meet the criteria for COPD between September 1997 and September 1998. There were no age limits (range: 53-90 years). The sample was 67% female. Survival status at follow-up after a mean of 803 days was measured. RESULTS: At follow-up, 16 patients had died. Depression significantly reduced the mortality risk at follow-up (hazard ratio, 0.30; 95% confidence interval, 0.10-0.93; P = 0.037). The impact of depression remained after control for forced expiratory volume during the first second (FEV1), the only multivariate significant predictor of mortality in the data set (hazard ratio, 0.27; 95% confidence interval, 0.09-0.84; P = 0.024). CONCLUSION: Depression in out-patients suffering from COPD appears to be an independent protector for mortality. Additional studies in larger samples are needed to replicate this finding and to determine possible underlying pathogenetic mechanisms.