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. 2005 Apr;40(2):435–458. doi: 10.1111/j.1475-6773.2005.00366.x

Table 3.

Mortality Benefits of Transfer to Level I Trauma Center, Comparing Different Model Specifications

Model Estimated Mortality Benefit from Transfer to Level I Trauma Center (%) 95% CI (Bootstrapped with 1,000 Replications, Bias-Corrected)
Single-equation probit* 1.9 (−3.2%, 6.5%)
Instrumental variables, bivariate probit 10.1 (0.3%, 22.2%)
Bivariate probit, reduced covariates model 1 9.9 (−2.1%, 20.6%)
Bivariate probit, reduced covariates model 2§ 7.3 (0.1%, 20.3%)
Bivariate probit, reduced covariates model 3 12.6 (1.9%, 26.1%)
Two-stage, linear probability model 7.0 (0.04%, 13.8%)
*

Covariates include: whether the patient was transferred to a level I or level II trauma center; dichotomous variables for children <12 years old and adults >55 years old; gender; a history of comorbid condition(s); whether the patient was transferred within Oregon; log (ISS); Head Abbreviated Injury Scale (AIS) of 5; AVPU score=V; AVPU score=P; AVPU score=U; hypotension in the emergency department (ED).

Covariates include: whether the patient was transferred to a level I or level II trauma center; dichotomous variables for children <12 years old and adults >55 years old; gender; a history of comorbid condition(s); whether the patient was transferred within Oregon; log (ISS); Head AIS of 5; AVPU score=V; AVPU score=P; AVPU score=U; hypotension in the ED. Differential distance is used as the instrumental variable.

Covariates include primarily demographic variables: whether the patient was transferred to a level I or level II trauma center; whether the patient was transferred within Oregon; dichotomous variables for children <12 years old and adults >55 years old; gender; history of comorbid condition(s); log (ISS). Differential distance is used as the instrumental variable.

§

Covariates include mostly measures of injury severity: whether the patient was transferred to a level I or level II trauma center; log (ISS); AVPU score=V; AVPU score=P; AVPU score=U; hypotension, and head AIS=5; hypotension in the ED. Differential distance is used as the instrumental variable.

Covariates include: whether the patient was transferred to a level I or level II trauma center; dichotomous variables for adults >55 years old; whether the patient was transferred within Oregon; log (ISS); head AIS of 5; AVPU score=U. Differential distance is used as the instrumental variable.