Case mix, outcomes and comparison of risk prediction models for admissions to adult, general and specialist critical care units for head injury: a secondary analysis of the ICNARC Case Mix Programme Database

Table 3 Measures of model calibration and discrimination in admissions eligible for all models

Model	APACHE II	APACHE III	SAPS II	MPM II	ICNARC
AUC (95 percent CI)	0.74 (0.72, 0.75)	0.76 (0.75, 0.78)	0.81 (0.80, 0.83)	0.81 (0.80, 0.82)	0.84 (0.83, 0.85)
Hosmer-Lemeshow C*
χ²(10)	215	2,478	61.4	38.2	24.9
p value	<0.001	<0.001	<0.001	<0.001	0.006
Cox's calibration regression
Intercept (95 percent CI)	-0.26 (-0.33, -0.19)	0.50 (0.40, 0.60)	0.02 (-0.05, 0.10)	0.20 (0.12, 0.28)	0.17 (0.09, 0.26)
Slope (95 percent CI)	0.66 (0.62, 0.71)	0.61 (0.57, 0.65)	0.89 (0.84, 0.95)	1.04 (0.97, 1.10)	1.08 (1.02, 1.14)
χ²(2)	176	1,256	20.3	28.0	17.8
p value	<0.001	<0.001	<0.001	<0.001	<0.001
Brier's score	0.187	0.194	0.158	0.163	0.147

N = 5,393 (48.9 percent). APACHE, Acute Physiology And Chronic Health Evaluation; AUC, area under the receiver operating characteristic curve; CI, confidence interval; ICNARC, Intensive Care National Audit and Research Centre; MPM, Mortality Probability Models; SAPS, Simplified Acute Physiology Score.

ISSN: 1364-8535