Shock Index as a Predictor of Mortality in Trauma: A Systematic Review and Meta-Analysis of Observational Studies

The shock index (SI) is a rapid and practical physiological parameter used to identify decompensated shock and assess severity in cases of progressive hemodynamic decline. This study aims to determine an optimal SI cutoff for adult trauma patients (18 years or older). The research was conducted in accordance with MOOSE checklist for systematic reviews and a comprehensive search for observational studies through December 2023 in various databases. Search terms included “Shock index” AND “Trauma”. Statistical analysis encompassed the extraction of data on mortality, shock index, ROC for mortality, and cutoff point calculations from individual studies. A pooled ROC analysis was performed using a random-effects analysis model. Heterogeneity was assessed via Chi-square and I-squared calculations. Following rigorous search and assessment procedures, 6 studies comprising 292,171 participants were considered eligible for the meta-analysis. These studies predominantly featured retrospective observational cohorts. An optimal SI cut-off of greater than 0.75 was identified (Youden Index J = 0.5673). The combined ROC area value was found to be 0.779 (95 percent confidence interval: 0.707 to 0.852), indicating a statistically significant predictive value for shock index in trauma patient outcomes. The moderate inconsistency level (I-squared = 38.55 percent) highlights the need to account for methodological variations among the studies. The statistically significant aggregated ROC area value supports the utility of shock index as a diagnostic tool at a threshold of greater than 0.75, provided that neurological confounders are considered in neuro-trauma cases.