Table 1.

Algorithm used to select injuries described by the ACS

Injuries the ACS-COT considers life-threatening or critical	ICD9-CM codes	Assumptions/Notes
Carotid or vertebral injuries	900
Aorta or great vessel injuries	901
Cardiac rupture	861.0 and 861.1	Unable to identify cardiac rupture from diagnosis codes so included all cardiac injuries.
Bilateral pulmonary contusions with PaO2/FiO2 ratio<200	-	Unable to identify based on discharge codes
Major abdominal vascular injury	902
Grade IV or V liver injury with >6 units pRBC	864.04 or 864.14	Unable to identify RBC transfusion so included all Grade IV liver lacerations
Unstable pelvic fracture with >6 units pRBC	808.43 or 808.53	Unable to identify unstable fractures so used the surrogate of the disrupted pelvic circle.
Fracture or dislocation with loss of distal pulses	903.1 – 903.3 in conjunction with 812, 813, and 818 904.1-904.5 in conjunction with 821, 822, 823, 824, and 827	Unable to identify fractures with loss of pulses so used the surrogate of fracture with vascular injury. Excluded patients with amputations, which would technically fit into this category, because of the problem of misclassification
Open skull fracture or penetrating injury	800.5-800.9 801.5-801.9 803.5-803.9 804.5-804.9	Unable to identify penetrating injury so captured only the open skull fractures.
GCS<14 or lateralizing neurologic injury	800-804 850.2-850.5 851-854	Unable to calculate GCS from discharge diagnosis codes so used the fifth digit subclassification to identify patients who had either a moderate (1–24h) or prolonged (>24h) loss of consciousness (e.g. 852.03). We assumed these patients would appear clinically to have a GCS<14.
Spinal cord deficit or lateralizing neurologic sign	806 952-955.2 956-956.2
Spinal column fractures	-	Excluded because of the problem of misclassification.
>2 unilateral rib fractures or bilateral rib fractures	807.03-807.1 807.4-807.6	Unable to identify patients with bilateral rib fractures so included only patients with >2 rib fractures.
Open long bone fracture	812.1, 812.3, 812.5 813.1, 813.3, 813.5 820.1, 820.3, 820.5 821.1, 821.3, 821.5 823.1, 823.3, 823.5 824.1, 824.3, 824.5
Significant torso injury with advanced co- morbid disease	860.1, 860.3, 860.5 861.2-861.9 862-870	ICD9-CM codes indicated significant torso injury. We included patients who had these ICD9 codes as well as an Exlixhauser co-moribidity code.