Figure 1–

The Kaplan–Meier survival curves, adjusted for age, arterial oxygen partial pressure, Global Initiative for Chronic Obstructive Lung Disease classification, forced vital capacity (FVC) % pred, forced expiratory volume in 1 s to FVC ratio, total lung capacity (TLC) % pred, functional residual capacity % pred, inspiratory capacity to TLC ratio, residual volume % pred, body mass index and arterial carbon dioxide partial pressure for the four population groups, categorised by carbon monoxide transfer factor (T_LCO) % pred quartiles.