Determining the Optimal Cutoff Value for the Reverse Shock Index Multiplied by the Glasgow Coma Scale for the Prediction of In-Hospital Mortality in Pediatric Trauma Patients: A Retrospective Cohort Study

<b>Background/Objectives</b>: Despite the growing burden caused by pediatric trauma, the accuracy of prehospital triage remains suboptimal due to the lack of reliable pediatric-specific tools. In this study, we aimed to evaluate the predictive validity of the reverse shock index multiplied by the Glasgow Coma Scale (rSIG) for in-hospital mortality in pediatric trauma patients and to determine appropriate age-specific rSIG cutoff values for triage use. <b>Methods</b>: We conducted a multicenter retrospective observational study using data from the Korean Emergency Department-Based Injury In-Depth Surveillance registry; these data covered trauma patients aged ≤18 years, spanning the period from 2011 to 2022. The rSIG was calculated using the initial vital signs and Glasgow Coma Scale scores upon arrival at the emergency department. Age groups with shared rSIG cutoffs were identified using the area under the receiver operating characteristic curve (AUC) and Akaike information criterion. Cutoff values were derived using the Youden index or further optimized to align with triage goals (<5% under-triage, <35% over-triage). <b>Results</b>: Among 333,995 pediatric trauma patients, the in-hospital mortality rate was 0.07%. The rSIG cutoff values derived using the Youden index showed strong predictive performance, with an AUC of 0.920 (95% CI: 0.897-0.943). The cutoff values adjusted to meet triage goals-13.3 for those aged 0-9 years, 18.4 for 10-14 years, and 20.9 for 15-18 years-achieved the best balance, with 30.94% over-triage and 9.17% under-triage. <b>Conclusions</b>: The rSIG is a reliable predictor of in-hospital mortality in pediatric trauma cases. We recommend using cutoff values that are optimized to meet triage goals. Further research is warranted to develop standardized methods to derive triage-appropriate cutoff values.