Utility of the Shock Index as a Prognostic Predictor in Patients Undergoing Emergency Surgery for Trauma: A Single Center, Retrospective Study

<b>Background:</b> Shock index (SI) is calculated by dividing heart rate (HR) by systolic blood pressure (sBP) and is a useful tool for predicting the prognosis of trauma patients. This study aimed to determine whether SI is useful in predicting mortality in patients undergoing emergency surgery for trauma. <b>Methods</b>: We analyzed 1657 patients who underwent emergency surgery for trauma. Patients were divided into SI < 1 and SI ≥ 1 groups and the Glasgow Coma Scale (GCS), Injury Severity Score (ISS), revised trauma score (RTS), Korean Triage and Acuity Scale (KTAS), transfusion amount, and mortality were compared. Binary logistic regression analysis was performed to identify factors associated with mortality. <b>Results</b>: There were significant differences in GCS, ISS, RTS, and KTAS in the SI ≥ 1 group compared to the SI < 1 group (all <i>p</i>-values < 0.001). In the SI < 1 cohort, the mortality rate was 11% (144/1283), and in the SI ≥ 1 group the mortality rate was 33% (125/374) (<i>p</i> < 0.001). Age, GCS, ISS, SI ≥ 1, and KTAS were determined to be predictors of mortality by logistic regression analysis. In particular, SI ≥ 1 group members exhibited a high association with elevated mortality (OR, 2.498; 95% CI, 1.708-3.652; <i>p</i> < 0.01). <b>Conclusions</b>: Although SI alone has limitations in predicting the patient's prognosis, patients with SI ≥ 1 upon arrival at the emergency room are associated with mortality of patients undergoing emergency surgery for trauma, along with already known trauma assessment systems such as GCS, ISS, and KTAS.