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 V̇O_2peak.

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 V̇O_{2 peak}, heart rate (HR), minute ventilation (V̇_E)_, 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 V̇_E/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 V̇O_2peak (R²= 0.131; Adj R ² = 1.25), including HR (β=0.5757; t = 5.7; P<0.001) and forced expiratory volume in one second (FEV₁) (β=0.119; t = 2.16; P<0.03). Among the Weber C + D groups, predictors of V̇O_2peak (R = 0.78; R²= 0.60; Adj R² =0.59), dyspnea (β=0.076; t = 1.111; P<0.27) and maximal voluntary ventilation (MVV) (β=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.