Figure 4.

Comparison of our prediction model with other, widely used models. The final study model (blue line) used on all episodes of severe sepsis showed good calibration (Hosmer-Lemeshow (HL) chi-squared 15.3, P = 0.06) and good discrimination (area under the curve (AUC)- receiver-operating characteristics (ROC) curve, 0.76). Acute Physiologic and Chronic Health Evaluation (APACHE) II, Mortality Probability models II₀ (MPM0 II) and Simplified Acute Physiology Score (SAPS) II scores were significantly less accurate than our model, with AUCs of 0.73, 0.66 and 0.72, respectively (P value < 10^-4 in all cases), and poor calibration (HL chi-squared P values of 0.03, < 10^-4 and 0.02, respectively).