The APACHE II and SAPS II-based models showed good discrimination ( area under the curve ( AUC ) 0.79 , 95 % confidence interval ( CI ) 0.75 to 0.82 ; and 0.80 , 95 % CI 0.77 to 0.83 , respectively ) , calibration ( P > 0.05 ) and precision ( Brier score 0.166 to 0.167 ) .