Fig. 4

Roc curve for risk 30-day (a) and 60-day (b) mortality predicted by the CART analyses. Solid line applies for derivation sample and dashed line applies for validation sample. The cut-off point of estimated risk dichotomization for optimal sensitivity-specificity combination for derivation sample is shown in grey with the corresponding sensitivity and specificity values. a 30-day mortality: AUC = 0.835 and 95 % confidence interval is (0.783, 0.888) for derivation sample and AUC = 0.794 and 95 % confidence interval is (0.723, 0.865) for validation sample. b 60-day mortality: AUC = 0.817 and 95 % confidence interval is (0.776, 0.859) for derivation sample and AUC = 0.770 and 95 % confidence interval is (0.716, 0.823) for validation sample