The performance of the reference model was comparable to the APACHE II and SAPS II in terms of discrimination ( AUC 0.77 ; compared to APACHE II , AUC -0.02 , P = 0.425 ; compared to SAPS II , AUC -0.03 , P = 0.218 ) , calibration ( P > 0.05 ) and precision ( Brier score 0.181 ) .