Impact of Admission Route on In-Hospital Mortality in Patients with Traumatic Brain Injury: A Retrospective Observational Study of a Single Major Trauma Center in South Korea

<b>Background/Objectives:</b> The optimal transport strategy for patients with traumatic brain injury (TBI) remains debated, particularly in trauma systems where inter-hospital transfer is common. Whether secondary transfer independently influences mortality after risk adjustment is unclear. This study aimed to evaluate the association between admission route and in-hospital mortality among patients with TBI at a major trauma center (MTC). <b>Methods:</b> This retrospective observational study included 417 patients with TBI and an Abbreviated Injury Scale (AIS) head score ≥ 3 (direct admission: 245; inter-hospital transfer: 172). Severe TBI was defined as a total Glasgow Coma Scale (GCS) score ≤ 8 or the need for advanced airway management. Multivariable logistic regression was performed to assess whether admission route was independently associated with in-hospital mortality after adjustment for age, physiological status at MTC arrival, and injury severity. Subgroup analysis was conducted in patients with severe TBI. <b>Results:</b> Crude mortality was higher in the direct admission group than in the transfer group (40.8% vs. 26.7%; <i>p</i> = 0.003), despite significantly longer injury-to-trauma center arrival times in transferred patients (219.0 vs. 44.0 min). In multivariable analysis, admission route was not independently associated with mortality in the overall cohort (adjusted odds ratio [aOR] 0.75; 95% CI 0.44-1.28; <i>p</i> = 0.298) or in the severe TBI subgroup (<i>n</i> = 233; aOR 0.88; 95% CI 0.47-1.67; <i>p</i> = 0.705). Increasing age and lower GCS motor scores were consistently associated with higher mortality in both analyses. <b>Conclusions:</b> Inter-hospital transfer was not independently associated with increased in-hospital mortality among patients with TBI. After consideration of patient age and neurological severity, initial stabilization at a nearby hospital followed by transfer may be an acceptable transport strategy for patients who present with physiological instability requiring immediate resuscitative interventions.