Epidemiology of moderate traumatic brain injury and factors associated with poor neurological outcome

OBJECTIVE The objective of this study was to investigate the epidemiology of moderate traumatic brain injury (TBI) and factors associated with poor neurological outcome. METHODS This multicenter retrospective cohort study used data from the Japan Trauma Data Bank from 2019 to 2022, including adult patients (aged > 17 years) with moderate TBI (Glasgow Coma Scale [GCS] score of 9–12). Patient characteristics, injury mechanism, details of intracranial injury, treatment, and outcome were investigated. Multivariate mixed-effects logistic regression analysis was used to examine factors associated with poor neurological outcome. Poor neurological outcome was defined as a Glasgow Outcome Scale score ranging between 1 and 3. RESULTS A total of 1638 patients were included in the study; 67% were male, with a median age of 73 years and a median Injury Severity Score (ISS) of 17. The major mechanism of injury was falls in 545 patients (33%); subdural hematoma and cerebral contusions were both common intracranial injuries in 482 study participants (29%) each. Two hundred forty-seven patients (15%) underwent craniotomy and 366 (22%) were managed with mechanical ventilation. There were 765 patients (47%) with poor neurological outcome, of whom 215 (13%) died in the hospital. Older age (≥ 65 years; adjusted odds ratio [aOR] 4.66, 95% CI 3.54–6.12), higher Charlson Comorbidity Index (CCI; aOR 1.27, 95% CI 1.14–1.42), GCS scores of 9 (aOR 1.50, 95% CI 1.08–2.09) and 10 (aOR 1.37, 95% CI 1.01–1.85), and severe trauma (ISS > 15; aOR 1.93, 95% CI 1.49–2.50) were associated with poor prognosis. Additionally, patients who required mechanical ventilation (aOR 1.76, 95% CI 1.27–2.42) and craniotomy (aOR 1.57, 95% CI 1.08–2.28) had a poor neurological outcome. Administration of tranexamic acid (aOR 0.74, 95% CI 0.58–0.94) and intensive care unit (ICU) admission (aOR 0.69, 95% CI 0.52–0.93) were associated with improved neurological outcome. CONCLUSIONS Almost half of the patients with moderate TBI had poor neurological outcome at hospital discharge. Several factors including older age, higher CCI, GCS scores of 9 or 10, severe trauma, and mechanical ventilation or craniotomy were found to be associated with poor neurological outcome in patients with moderate TBI. Additionally, these data suggest that tranexamic acid administration and admission to the ICU might be important for improving prognosis. Further investigations are warranted to elucidate the appropriate management for patients with moderate TBI.