Value of cardiopulmonary exercise testing in the assessment of symptoms and quality of life in Asian patients with chronic obstructive pulmonary disease

BACKGROUND: The natural course of chronic obstructive pulmonary disease (COPD) is characterized by symptom exacerbation and quality-of-life reduction. Therefore, symptoms should be properly assessed. Some studies have demonstrated a weak correlation between cardiopulmonary exercise testing (CPET) parameters and symptoms in patients with COPD; however, data on Asian patients are lacking. We investigated the value of CPET parameters in assessing symptoms and quality of life in Asian patients with COPD. METHODS: Of 681 patients who underwent CPET at Asan Medical Center between January 2020 and June 2022, we analyzed 195 patients with COPD in this retrospective study. A cycle ergometer was used for the incremental protocol. The modified Medical Research Council (mMRC) dyspnea scale and COPD Assessment Test (CAT) were administered to assess the patients’ symptoms. RESULTS: The mMRC grade was related to maximal oxygen uptake (VO(2) max, L/min) (Spearman’s correlation coefficient ρ=−0.295, P<0.001) and physiological dead space/tidal volume ratio at peak exercise (V(D)/V(T) peak) (ρ=0.256, P<0.001). The CAT score was significantly correlated with VO(2) max (L/min) (Spearman’s correlation coefficient ρ=−0.297, P<0.001) and V(D)/V(T) peak (ρ=0.271, P<0.001), but had no correlation with breathing reserve (ρ=−0.122, P=0.089). The optimal cut-off values of VO(2) max and V(D)/V(T) peak for predicting the onset of clinically significant dyspnea were 1.099 L/min and 0.295, respectively. CONCLUSIONS: VO(2) max and V(D)/V(T) peak comprehensively reflect the symptoms and health-related quality of life of patients with COPD.