FIG. 4.

Calibration tests for the newly developed IMPACT–APACHE II models in the validation cohort. Calibration for mortality prediction (left) and for neurological outcome prediction (right). The H-L calibration plots (left; with a loess smoother curve fitted between the groups) and the GiViTI calibration belts (right) for mortality and neurological outcome, respectively. All new models showed good calibration by the H-L test (p>0.05). Only the IMPACText–APACHE II showed poor calibration by the H-L test (p=0.037). Accordingly, the GiViTI calibration belt reveals significant under prediction (95% confidence interval over the diagonal bisector line) between for a risk interval between 0.61 and 0.97. IMPACT, International Mission for Prognosis and Analysis of Clinical Trials; APACHE II, Acute Physiology and Chronic Health Evaluation II; H-L, the Hosmer-Lemeshow Ĉ-test; GiViTI, Italian Group for the Evaluation of Interventions in Intensive Care Medicine.