Fig. 3
ROC curve for FVC/DLCO and survival curves of study population II. A ROC curve for FVC/DLCO as related to 5-year all-cause mortality of COPD patients. The cut-point of FVC/DLCO value was 0.41 l/mmol/min/kPa. B Kaplan–Meier survival curves of COPD patients according to the cut-point of FVC/DLCO. Red line refers to FVC/DLCO ≥ 0.41 l/mmol/min/kPa, and blue line refers to FVC/DLCO < 0.41 l/mmol/min/kPa. ROC receiver operating characteristic