TABLE IV.

Inverse Probability of Treatment-Weighted Estimates of the Relative Risk of Mortality Given Treatment Delay (Greater than Twelve Hours) Stratified by Severity of Associated Injury

	Low Severity (AIS <3)*		High Severity (AIS ≥3)*
Associated Injury	Relative Risk (95% Confidence Interval)	N	Relative Risk (95% Confidence Interval)	N	P Value†
Extremity/pelvic fracture	0.58 (0.33 to 1.20)	1846	0.73 (0.39 to 1.36)	1223	0.63
Abdomen	0.82 (0.54 to 1.35)	2261	0.36 (0.13 to 0.87)	808	0.09
Chest	0.67 (0.32 to 1.37)	1373	0.64 (0.39 to 1.11)	1696	0.90
Head/neck	0.71 (0.37 to 1.77)	1923	0.62 (0.40 to 0.99)	1146	0.74

^*AIS = Abbreviated Injury Score.

^†The p values test the equality of treatment effects between low and high-severity associated injury subgroups.