<p>Complete-case availability by model.</p>

Overall mortality was 41.1% (51/124), with 24-hour mortality of 23.7% (28/118). The Glasgow Coma Scale (GCS) was the strongest independent predictor across all models (OR = 0.77–0.79 per point, p < 0.001). In the primary ED arrival model (AUC = 0.770), GCS was the sole significant predictor; GCS alone achieved a comparable AUC of 0.771.

The exploratory model incorporating transfusion variables achieved the highest discrimination (AUC = 0.828). All models showed adequate calibration (Hosmer–Lemeshow p > 0.05). Mortality decreased with longer time-to-first-transfusion (54.5% for ≤15 min vs. 23.7% for >60 min, trend p = 0.007), reflecting confounding by indication.

In massively transfused trauma patients without severe TBI, GCS assessed at ED arrival is the single most informative predictor of mortality, enabling risk stratification before laboratory results become available. Metabolic acidosis markers and coagulopathy were strongly associated with mortality on univariate analysis but added no independent predictive value beyond GCS. Time-to-first-transfusion appeared to reflect hemorrhage acuity rather than a modifiable prognostic factor.</p></div>