Fig. 2

Receiver operating characteristics (ROC) curve for forced expiratory flow at 50% of FVC, FEF_50% %predicted, in the derivation cohort as a predictor of methacholine responsiveness. Values in red represent the respective FEF_50% %predicted cut-off values. AUC = Area under the curve. Line of unity is represented by a grey line, corresponding to AUC = 0.5