Fig. 3
Mortality prediction model. a A decision tree predicting post-AE 90-day survival created by recursive partitioning. The splitting process was terminated when the study cohort was divided into the following three groups: mild, moderate and severe. The variables (cut-off points) of the optimal split in the first and second split candidates were baseline %FVC (63%) and P/F at AE (225 Torr), respectively. b The post-AE 90-day mortality rates of the patients classified by the decision tree: mild group, 20.8%, moderate group, 64.0% and severe group, 88.9% (P = 0.0002), with a discriminative performance (C-index) of 0.775. %FVC percent predicted forced vital capacity, P/F PaO2/FiO2 ratio, AE acute exacerbation