Performance of the glucose-potassium ratio as a biomarker of mortality in children with severe traumatic brain injury.

Introduction: Blood biomarkers are substances that respond to cellular, biochemical and/or molecular changes and can be measured to provide information on a patient´s pathophysiological state. Traumatic brain injury (TBI) causes changes in certain biomarkers due to mechanical cell membrane disruption and excitation of membrane potential. The scope of this study is to evaluate the performance of glucose-potassium ratio (GPR) as a predictive biomarker of mortality in children and adolescents with severe TBI hospitalized in a level 1 Brazilian trauma center.

Methods: Cross-sectional analytical study carried out in a Brazilian trauma reference center through the review of consecutive medical records of children with severe TBI hospitalized between 2016 and 2023. We analyzed blood glucose (BG) and potassium values obtained in the first 24 hours after TBI. GPR was calculated retrospectively by dividing BG values by potassium values. The performance of GPR as a predictor of mortality was analyzed using the receiver operating characteristic (ROC) curve.

Results: We included 40 children with severe TBI with a mean age of 9 years (SD ± 5.5 years). Hyperglycemia was observed in 33% and hypokalemia in 58% of the patients, and GPR ≥ 50 was found in 43% of the patients. With a mortality rate of 23%, the ROC showed an area under the curve (AUC) of 0.71, and the cutoff point of 50 in GPR showed a negative predictive value of 91%.

Conclusion : The AUC-ROC of 0.71 indicates a moderate performance of GPR as a predictive biomarker of mortality in children with severe TBI. The cutoff point 50 in the GPR has a high negative predictive value, making it possible to identify children with a lower probability of death among pediatrics patients with severe TBI.