Measure of association for primary and secondary outcomes
| OR (95% CI) | P value | |
| Empyema | 1.51 (0.42 to 5.42) | 0.53 |
| Pneumonia | 1.61 (0.86 to 3.03) | 0.14 |
| Death | 0.55 (0.25 to 1.22) | 0.14 |
| Pneumonia or death | 1.17 (0.77 to 1.77) | 0.46 |
| Clostridium difficile colitis | 0.65 (0.09 to 4.48) | 0.66 |
| Rate ratio (95% CI) | P value | |
| ICULOS | 1.35 (0.93 to 1.96) | 0.11 |
| Hospital LOS | 1.15 (0.95 to 1.40) | 0.15 |
| Ventilation days | 1.43 (0.86 to 2.39) | 0.17 |
Logistic regression for binary outcomes and negative binomial regression for count outcomes, both with random effects of matched pairs and trauma centers.
ICULOS, intensive care unit length of stay.