BACKGROUND: Early transfusion improves survival of traumatic hemorrhage. We hypothesized that increased ratios of prehospital to total blood (red blood cell or whole blood) transfusion within 24 hours would be associated with improved outcomes. METHODS: A retrospective cohort study using a harmonized database of six hemorrhagic shock trials was conducted. Decedents within 4 hours and those not transfused within 24 hours were excluded. The primary outcome was 24-hour mortality; secondary outcomes included 28-day mortality, intensive care unit (ICU)-free and ventilator-free days, and incidence of acute lung injury (ALI). Prehospital blood ratio was calculated as volume prehospital transfusion:volume 24-hour total transfusion (prehospital plus 24-h total at the admitting facility). Multivariable analyses adjusted for age, sex, mechanism, Injury Severity Score (ISS), inter-facility transfer, transport mode, arrival systolic blood pressure and Glasgow Coma Scale, treatment group, trial, and transfusion volume were conducted. Sensitivity analyses (prehospital-only recipients, excluding traumatic brain injury) were conducted. RESULTS: Overall, 2,340 subjects were eligible, and 1,024 (43.8%) received prehospital blood. Prehospital recipients were older (median age 41 vs. 38 y, P =0.013), more likely blunt mechanism (81.6% vs. 66.0%; P <0.001), more likely transferred (13.3% vs. 4.3%; P <0.001), more likely transported by air (77.4% vs. 47.1%; P <0.001), and had higher ISS (median 29 vs. 25, P <0.001) compared with in-hospital only recipients. For every 10% increase in prehospital (PH):total blood ratio, there was an 8.8% decrease in odds of ALI (95% CI: 1.8-15.4%; P =0.015) and no significant association with mortality, ICU-free or ventilator-free days. Among prehospital recipients, for every 10% increase in PH:total blood ratio, there was a 16.7% decrease in odds of ALI (95% CI: 5.3-26.6%; P =0.005; n=375) and 0.21 (95% CI: 0.01-0.41; P =0.036; n=909) more ICU-free days. CONCLUSIONS: An increased proportion of resuscitation in the prehospital phase of care was associated with improved secondary clinical outcomes for select subjects. These data support initiating transfusion for hemorrhage as early as feasible. ( J Trauma Acute Care Surg . 2026;00: 000–000. Copyright© 2026 Wolters Kluwer Health, Inc. All rights reserved.) LEVEL OF EVIDENCE: Therapeutic/Care Management; Level III.
Furman et al. (Fri,) studied this question.