Predictors of cardiopulmonary exercise testing in COPD patients according to the Weber classification.

BACKGROUND: Weber classification stratifies cardiac patients based on peak oxygen consumption (V̇O2), the gold-standard measure of exercise capacity. OBJECTIVE: To determine if Weber classification is a useful tool to discriminate clinical phenotypes in COPD patients and to evaluate if disease severity and other clinical measures can predict V̇O2peak. METHODS: Three hundred and six COPD patients underwent cardiopulmonary exercise testing (CPX) and were divided according to Weber class: 1) Weber A (n = 34); 2) Weber B (n = 88); 3) Weber C (n = 138); and 4) Weber D (n = 46). RESULTS: Weber class D patients demonstrated a reduced V̇O2 peak, heart rate (HR), minute ventilation (V̇E), oxygen (O2) pulse, circulatory power (CP), oxygen uptake efficiency slope (OUES), oxygen saturation (SpO2%), delta (Δ)HR and ΔSpO2 when compared to Weber A and B (p<0.05). Moreover, Dyspnea and the V̇E/carbon dioxide production (V̇CO2) slope were higher in Weber D compared with Weber C and A (p<0.001). Hierarchical regression analysis demonstrated significant predictors of V̇O2peak (R2= 0.131; Adj R 2 = 1.25), including HR (ß=0.5757; t = 5.7; P<0.001) and forced expiratory volume in one second (FEV1) (ß=0.119; t = 2.16; P<0.03). Among the Weber C + D groups, predictors of V̇O2peak (R = 0.78; R2= 0.60; Adj R2 =0.59), dyspnea (ß=0.076; t = 1.111; P<0.27) and maximal voluntary ventilation (MVV) (ß=0.75; t = 1.14; P<0.00). CONCLUSION: Weber classification may be a useful tool to stratify cardiorespiratory fitness in COPD patients. Other clinical measures may be useful in predicting peak V̇O2 in mild-to-severe COPD, moreover different phenotypes may be important tool to improve physical capacity of chronic disease patients.