Table 5.
The adjusted time-outcome association for the full TBI cohort and subgroups (outcome = 6-month GOSE ≤ 4) using different out-of-hospital time variables.*
| Total EMS time (minutes) | All patients (n=1,239) |
Ground (n=742) |
Air (n=497) |
ISS > 15 (n=951) |
Required critical intervention (n=393) |
|||||
|---|---|---|---|---|---|---|---|---|---|---|
| OR | 95% CI | OR | 95% CI | OR | 95% CI | OR | 95% CI | OR | 95% CI | |
| Polytomous | ||||||||||
| ≤ 30 | 1.00 | reference | 1.00 | reference | 0.37 | (0.06, 2.32) | 1.00 | reference | 1.00 | reference |
| 30-45 | 0.92 | (0.57, 1.49) | 1.20 | (0.71, 2.05) | 0.51 | (0.08, 3.20) | 0.82 | (0.47, 1.44) | 1.33 | (0.51, 3.50) |
| 45-60 | 1.23 | (0.73, 2.07) | 1.58 | (0.85, 2.92) | 1.00 | reference | 1.06 | (0.58, 1.95) | 1.77 | (0.59, 5.33) |
| > 60 | 0.83 | (0.45, 1.52) | 0.90 | (0.39, 2.07) | 0.28 | (0.04, 1.74) | 0.68 | (0.34, 1.35) | 1.47 | (0.44, 4.98) |
| Dichotomous | ||||||||||
| > 60 | 0.77 | (0.51, 1.15) | 0.70 | (0.35, 1.43) | 0.58 | (0.33, 1.01) | 0.71 | (0.45, 1.10) | 0.96 | (0.43, 2.16) |
| Continuous | ||||||||||
| per 5 min | 0.98 | (0.95, 1.01) | 1.02 | (0.95, 1.09) | 0.94 | (0.91, 0.99) | 0.97 | (0.94, 1.01) | 1.01 | (0.93, 1.09) |
| Spline | ||||||||||
| ≤ 30 | 0.82 | (0.54, 1.25) | 0.96 | (0.62, 1.50) | 0.31 | (0.02, 4.84) | 0.77 | (0.45, 1.31) | 0.65 | (0.26, 1.63) |
| 30-45 | 1.11 | (0.91, 1.36) | 1.22 | (0.96, 1.55) | 1.14 | (0.71, 1.83) | 1.05 | (0.83, 1.32) | 1.13 | (0.74, 1.74) |
| 45-60 | 0.98 | (0.82, 1.17) | 0.86 | (0.65, 1.15) | 0.94 | (0.72, 1.23) | 0.98 | (0.81, 1.20) | 1.04 | (0.71, 1.50) |
| > 60 | 0.97 | (0.93, 1.01) | 1.00 | (0.85, 1.17) | 0.94 | (0.90, 0.99) | 0.97 | (0.93, 1.01) | 1.00 | (0.89, 1.11) |
Abbreviations: AIS, Abbreviated Injury Scale; CI, confidence interval; EMS, emergency medical services; GCS, Glasgow Coma Scale; GOSE, Glasgow Outcome Scale - Extended; ISS, Injury Severity Score; OR, odds ratio; SBP, systolic blood pressure.
The following covariates were included in the model: age (spline with one knot at 45 yrs), gender, ISS, head AIS, initial SBP category, heart rate category, initial GCS, advanced airway attempt, air transport (except for ground and air subgroups), and site. Multiple imputation used for the following variables (counts in parentheses): age (1), ISS (31), head AIS (8), heart rate (2), SBP (10), GCS (1), and GOSE (185). Partial AIS data were available for 27 of the 31 patients missing ISS score. Time is modeled using four different methods: polytomous with reference category ≤ 30 minutes, dichotomous with reference category ≤ 60 minutes, continuous (per 5 minute increments), and spline (per 5 minute time difference in each range).