Does exercise capacity, dyspnea level, or quality of life actually predict mortality in patients with COPD? 8-year follow-up.

ABSTRACT

INTRODUCTION: The goals of chronic obstructive pulmonary disease (COPD) treatment are to relieve dyspnea, increase exercise capacity, and improve quality of life. The relation of exercise capacity, dyspnea level, and quality of life with long-term mortality is unclear. Aim of the study was to assess the effect of exercise capacity, dyspnea level and quality of life on long-term mortality risk in patients with COPD. MATERIALS AND METHODS: Dyspnea level was assessed using the modified Medical Research Council (mMRC), Borg and Baseline Dyspnea Index (BDI) and Body Obstruction Dyspnea Exercise (BODE), health-related quality of life with St. George's Respiratory Questionnaire, and exercise capacity with the 6-minute walking test (6MWT) and cardiopulmonary exercise test. At the end of 8-year follow-up period, the relation between these tests and mortality was examined. RESULT: A total of 42 patients with stable COPD were included in the study. Sixteen patients died during the approximately 8-year follow-up period. Univariate analysis revealed that VO2 peak [HR 1.845; CI (1.336-2.55); p<0.001], BODE index [HR 0.787; CI (0.703-0.880); p<0.001], and SGRQ [HR 1.073; CI (1.028-1.119); p= 0.001] were significantly correlated to mortality risk. Multivariate Cox regression analysis revealed VO2 peak [HR 1.031; CI (0.683-1.120); p= 0.01] as the single significant predictor of mortality. VO2 peak less than 22.5 had a sensitivity of 82%, specificity of 80%, and area under the curve of 0.142 [95% CI (0.027-0.257); p< 0.001] for mortality risk with ROC analysis. CONCLUSIONS: Cardiopulmonary disturbances during maximal exercise may be an important indicator of mortality risk.