Reverse shock index multiplied by Glasgow Coma Scale score as a predictor of urgent trauma care and mortality in isolated severe traumatic brain injury: a 10-year nationwide validation study

Abstract

Background: Patients with traumatic brain injuries (TBIs) have high mortality rates and poor outcomes. Predicting the need for urgent interventions, as well as mortality risk, is crucial for optimizing trauma management. This study aimed to identify and validate the reverse shock index multiplied by the Glasgow Coma Scale score (rSIG) as an assessment tool for predicting urgent interventions, critical care, and mortality in patients with isolated severe TBIs.

Methods: This retrospective nationwide validation study analyzed data from the Japan Trauma Data Bank between January 1, 2012, and December 31, 2021. The population was divided into derivation (2012-2018) and validation (2019-2021) cohorts. The primary composite outcome included blood transfusions within 24 hours of hospital arrival, craniotomy or craterization, intracranial pressure (ICP) monitoring, tracheal intubation, intensive care unit (ICU) admission, and in-hospital mortality. The optimal rSIG cutoff for predicting urgent interventions was determined using the Youden Index, and gray-zone analysis was performed as sensitivity.

Results: A total of 42,375 patients were analyzed (derivation cohort, n = 32,483; validation cohort, n = 9,892). The optimal rSIG cutoff point for predicting urgent intervention was 16.21. When applied to the validation cohort, the model demonstrated moderate discrimination (AUC 0.655, 95% CI 0.644-0.666). For predicting surgical intervention was 16.46, yielding as AUC 0.627 (95% CI 0.614-0.639), sensitivity of 53.2%, specificity of 72.1%, positive predictive value of 29.2%, and negative predictive value of 87.7%. Patients with abnormal rSIG values ( < 16.21) had significantly higher rates of urgent interventions, ICU admission, and in-hospital mortality (all p < 0.01). In the gray-zone analysis, rSIG values ≤6, 6-35, and ≥35 defined high-, moderate-, and low-risk groups, respectively; the high-risk group showed the greatest need for urgent trauma care and highest mortality (p < 0.001).

Conclusions: The rSIG may serve as a simple and practical indicator for predicting urgent interventions, critical care, and mortality in patients with isolated severe TBIs. Its simplicity and rapid calculability support its potential use as a triage tool in prehospital settings and as a clinical diagnostic aid in hospital environments.

Keywords: Critical care; Emergency care; Japan Trauma Data Bank; Reverse shock index multiplied by the Glasgow Coma Scale score; Traumatic brain injury.