Four-Variable Artificial Neural Network Model. A- ROC Curve for the simplified ANN-4 training cohort (solid line, n = 86 patients, AUC was 0.88 ± 0.04) and ANN-4 validation cohort (dashed line, n = 21 patients, AUC = 0.95 ± 0.06) B- Actual vs. Predicted outcomes plot; the correlation between actual and predicted death via simple linear regression on all 107 patients, using the training set-derived algorithm, was r2 = .52. RMSE = 0.34. Dotted lines represent the 95% confidence band. Axes: 0- survival (predicted or actual); 1- in-hospital mortality (predicted or actual)