Table 4.

Subgroup analyses describing the association of the protocol periods with severity-adjusted hospital mortality

Subgroup	Variable	Odds ratio (95% CI)	P-value
High severity of illness
	Predicted mortality, %	1.040* (1.036 – 1.043)	< 0.001
	Protocol period
	Pre-protocol	Reference
	Transition	0.831 (0.701–0.984)	0.031
	Protocol	0.754 (0.625–0.910)	0.003
Low severity of illness
	Predicted mortality, %	1.241* (1.191 – 1.293)	< 0.001
	Protocol period
	Pre-protocol	Reference
	Transition	1.013 (0.730–1.406)	0.938
	Protocol	0.733 (0.492–1.093	0.128
Long ICU length of stay
	Predicted mortality, %	1.033* (1.029 – 1.036)	< 0.001
	Protocol period
	Pre-protocol	Reference
	Transition	0.893 (0.746–1.069)	0.217
	Protocol	0.745 (0.609–0.910)	0.004
Short ICU length of stay
	Predicted mortality, %	1.077* (1.071 – 1.083)	< 0.001
	Protocol period
	Pre-protocol	Reference
	Transition	0.829 (0.620–1.109)	0.207
	Protocol	0.953 (0.686–1.325)	0.776

CI = Confidence interval

*This odds ratio reflects the risk of death per 1% rise in the predicted mortality rate for the entire study population.