Influence of multiple trauma on the effect of transfusion strategies in patients with traumatic brain injury: a sub-study of the HEMOTION trial

PURPOSE: In moderate-to-severe traumatic brain injury (TBI), anemia may exacerbate secondary cerebral injury, and patients with multiple trauma may be especially vulnerable to cerebral hypoxia. We conducted a secondary analysis of the HEMOTION trial (liberal transfusion strategy > 10 g/dL vs. restrictive > 7 g/dL), to assess whether multiple trauma modifies the effect of transfusion strategy after moderate-to-severe TBI. METHODS: We included all HEMOTION trial participants (n = 742) and defined multiple trauma using three definitions: (1) extracranial injury with Injury Severity Score (ISS) > 15; (2) extracranial injury requiring emergency extracranial surgery; (3) spinal injury with neurological deficit. The primary outcome was the 6-month Glasgow Outcome Scale Extended (GOS-E). We tested interactions between transfusion strategy and multiple trauma status using sliding dichotomy and hierarchical Poisson regression, with sensitivity analyses using classical dichotomy (GOS-E ≤ 4) and proportional odds models. Secondary outcomes included mortality, quality of life (EQ-5D-5L, QOLIBRI), functional independence (FIM), and depression (PHQ-9). RESULTS: We found no interaction between multiple trauma status and transfusion strategies on the 6-month GOS-E across all three definitions. The adjusted relative risk (RR) of an unfavourable outcome with the liberal strategy was 0.87 (95% CI 0.71-1.07) for patients with ISS > 15, 0.79 (0.59-1.05) for emergency extracranial surgery, and 0.99 (0.42-2.33) for spinal cord injury. Sensitivity analyses suggested a potential interaction for patients undergoing emergency extracranial surgery (p-interaction = 0.02 for proportional odds analysis; 0.05 for classical dichotomy). A liberal strategy was associated with better FIM, EQ-5D-5L, and Qolibri scores for definitions 1 and 2, but not 3, with no consistent interaction. Mortality and PHQ-9 did not differ. CONCLUSION: Multiple trauma status was not associated with the effect of liberal vs. restrictive transfusion strategies on the GOS-E. Patients requiring emergency extracranial surgery may warrant further investigation.