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

Background: Patients with traumatic brain injuries (TBIs) have high mortality rates and poor outcomes. Predicting the mortality and need for emergency trauma care is important. There are few urgency indicators in patients with severe TBIs. This study aimed to identify and validate the reverse shock index multiplied by the Glasgow Coma Scale score (rSIG) as an assessment tool for emergency trauma care, including urgent interventions, critical care, and mortality in patients with severe TBIs. Methods: This retrospective validation study included patients of all ages with isolated severe TBIs with Abbreviated Injury Scale (AIS) scores ≥ 3 registered in the Japan Trauma Data Bank (JTDB) dataset between January 1, 2012, and December 31, 2021. The patients were divided into a derivation cohort (January 1, 2012, to December 31, 2018) and a validation cohort (January 1, 2019, to December 31, 2021). The primary outcome measure was a composite outcome of blood transfusions within 24 h of hospital arrival, craniotomy, craterization, intra-cranial pressure (ICP) monitoring, tracheal intubation, intensive care unit (ICU) admission, and in-hospital mortality. Results: A total of 42,375 eligible patients were divided into the derivation (n = 32,483) and validation (n = 9892) cohorts. The derivation cohort included male patients (n=21977, 68%); patients who underwent blood transfusions within 24 h of hospital arrival, craniotomies, and craterizations (n=3114, n=3678, and n=1277, respectively; 10%, 11%, and 4% respectively). The median rSIG and actual survival rate of the derivation cohort were 21.8 (interquartile range [IQR], 14.9–28.0) and 88%. The cut-off point of the rSIG was 16.21. Abnormal rSIGs were associated with a greater odds ratio (OR) for blood transfusions within 24 h of arrival (OR, 4.03; 95% confidence interval [CI], 3.59-4.53), craniotomies (2.86 [2.55-3.21]), craterization (2.61 [2.14-3.17]), ICP monitoring (4.91 [3.96-6.10]), tracheal intubation (6.40 [5.71-7.17]), ICU admission (2.10 [1.93-2.29]), and in-hospital mortality (8.49 [7.45-9.63]) than those with normal rSIGs. Conclusions: The rSIG may be a useful predictor of urgent interventions and neurological critical care, and in-hospital mortality in patients with isolated severe TBIs in the emergency hospital settings.