Table 6.

Survival benefit of HEMS measured by TRISS and RISC in the subgroup of level I trauma centers at daytime

	HEMS	GEMS	P-value
TRISS
Number of cases	2,294	2,156
Expected mortality	20.7%	18.1%	-
Observed mortality	13.4%	14.7%
Standardized Mortality Ratio (95% CI)	0.647 (0.579 to 0.714)	0.815 (0.732 to 0.897)	0.002
RISC
Number of cases	3,577	3,720
Expected mortality	18.4%	17.9%	-
Observed mortality	14.2%	15.5%
Standardized Mortality Ratio (95%-CI)	0.772 (0.710 to 0.834)	0.864 (0.799 to 0.928)	0.045

Only cases with sufficient data for calculation of score values were considered.