Initial Glasgow Coma Scale and Mortality after Traumatic Brain Injury: A Systematic Review and Narrative Synthesis of Prognostic Evidence

Abstract: Background: Traumatic brain injury (TBI) is a major cause of death and disability worldwide. Early neurological assessment is essential for risk stratification and clinical decision-making. The Glasgow Coma Scale (GCS) remains one of the most widely used tools for evaluating level of consciousness after acute brain injury. A lower initial GCS is generally associated with increased mortality, but its prognostic value may be modified by age, pupillary reactivity, computed tomography findings, hypoxia, hypotension, and extracranial injury. Objective: This review aims to evaluate the association between initial GCS and mortality in patients with traumatic brain injury. Methods: A systematic review framework was designed according to PRISMA 2020 recommendations. Eligible studies included observational cohorts, prognostic model studies, and meta-analyses reporting initial GCS and mortality after TBI. The main outcome was mortality, including in-hospital mortality, 14-day mortality, 30-day mortality, and 6-month mortality. Because of expected clinical and methodological heterogeneity, the present version provides a narrative synthesis supported by quantitative data from major studies. Results: Evidence from large international cohorts and prognostic models supports an inverse relationship between initial GCS and mortality. In the CRASH study, 10,008 adult patients with GCS ≤14 were included, and prognostic models were developed for 14-day mortality and 6-month death or severe disability. In the IMPACT study, 8,509 patients with moderate or severe TBI were used for model development and 6,681 patients for external validation. The strongest predictors of outcome were age, motor score, pupillary reactivity, and CT characteristics. A meta-analysis including 102,132 patients found that GCS predicted mortality with an area under the curve of 0.90. Conclusion: Initial GCS is an important predictor of mortality after traumatic brain injury. However, it should not be interpreted in isolation. Prognostic assessment should integrate GCS with age, pupillary response, CT findings, hypoxia, hypotension, and extracranial injury.