Supplemental Table 1. Sensitivity analysis comparing mixed effects Poisson regression with robust error variance using imputed versus non-missing SBP and base excess. We controlled for age, ISS, mechanism, severe head injury (AIS head ≥3), shock (base excess <-4 mEq/L), and hypotension (SBP <90 mmHg) as fixed effects and site as a random effect. Incidence-rate ratios and 95% confidence intervals describe ENDO versus OPEN and RT versus OPEN on outcome of in-hospital mortality. Model N included in model Variable RR 95% CI Missing SBP and base excess imputed 543 ENDO vs OPEN 0.58 0.46-0.73 RT vs OPEN 3.00 1.84-4.90   Transferred 9 OPEN patients with initial endovascular procedures to the ENDO group (missing data imputed) 0.61 0.46-0.82 2.99 1.76-5.10 Excluded patients with missing SBP or base excess data 478 0.57 0.45-0.72 3.14 1.98-4.98

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Supplemental Figure 1. Deviance residuals versus predicted for the overall model with imputed missing SBP and base excess data (n=543). Supplemental Figure 2. Actual (black) versus simulated deviance residuals (grey, n=20) using simulated data generated by the model in Figure 1. Supplemental Figure 3. Deviance residuals versus predicted for patients without BTAI with imputed missing SBP and base excess data (n=488). Supplemental Figure 4. Actual (black) versus simulated deviance residuals (grey, n=20) using simulated data generated by the model in Figure 3. Supplemental Figure 5. Deviance residuals versus predicted for patients with chest NCTH with imputed missing SBP and base excess data (n=137). Supplemental Figure 6. Actual (black) versus simulated deviance residuals (grey, n=20) using simulated data generated by the model in Figure 5. Supplemental Figure 7. Deviance residuals versus predicted for patients with abdomen NCTH with imputed missing SBP and base excess data (n=225). Supplemental Figure 8. Actual (black) versus simulated deviance residuals (grey, n=20) using simulated data generated by the model in Figure 7. Supplemental Figure 9. Deviance residuals versus predicted for patients with pelvis NCTH with imputed missing SBP and base excess data (n=167). Supplemental Figure 10. Actual (black) versus simulated deviance residuals (grey, n=20) using simulated data generated by the model in Figure 9.