Predictive value of the Shock Index for in-hospital mortality and blood transfusion in trauma patients: A retrospective study
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Abstract
The Shock Index (SI), defined as heart rate divided by systolic blood pressure, is a simple bedside marker of hemodynamic instability in trauma. However, its predictive value for primary clinical outcomes remains debated. This retrospective cohort study evaluated the ability of SI measured at emergency department admission to predict in-hospital mortality and the need for blood transfusion among adult trauma patients triaged as Level I or II at a single trauma center between 2021 and 2022. A total of 185 patients were included (mean age 62.2 ± 22.3 years; 36.8% female). In-hospital mortality occurred in 78 patients (42.2%), and 44 (23.8%) required transfusion. Overall, SI demonstrated limited discriminative performance for mortality (Area Under the Curve (AUC) = 0.574; 95% Confidence Interval (CI): 0.49–0.66; p = 0.088) and transfusion (AUC = 0.573; 95% CI: 0.49–0.66; p = 0.135). Optimal cutoffs showed modest sensitivity but poor specificity. In exploratory subgroup analyses with small sample sizes, higher discrimination was observed in select groups, including patients with Glasgow Coma Scale (GCS) 13–15 (AUC = 0.768); however, these findings should be interpreted cautiously. Multivariable Cox regression identified higher Injury Severity Score, lower Glasgow Coma Scale, and need for mechanical ventilation as independent predictors of mortality, whereas SI was not independently associated with survival. In this single-center cohort, SI showed limited overall utility as a standalone predictor of mortality or transfusion, and its potential role may be restricted to specific clinical contexts requiring further validation.
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