Diagnostic accuracy of shock index, revised trauma score, and injury severity score for mortality prediction in trauma: A hierarchical meta-analysis.

Background

Shock Index (SI) and Revised Trauma Score (RTS) are physiological tools available at the point of trauma triage. Injury Severity Score (ISS) is an anatomical score that requires completed injury characterization and is typically available only after initial resuscitation. Their comparative value for predicting mortality and whether ISS meaningfully adds to the acute tools remains unclear.

Aims

The aim of this systematic review and hierarchical meta-analysis is to pool the diagnostic accuracy of SI and RTS as acute mortality-prediction tools in adult trauma patients; to benchmark these against ISS; and to formally test, in studies reporting both, whether RTS and ISS differ in diagnostic accuracy.

Methods

Electronic databases were searched from inception to May 2026. In-hospital mortality was prespecified as the primary endpoint. Pooled sensitivity, specificity and hierarchical summary receiver operating characteristic (HSROC) analyses were performed with a bivariate random-effects model for each tool separately. For studies reporting both RTS and ISS in the same cohort, a paired comparison was performed using a bivariate model with test type as a covariate and a pooled within-study difference analysis.

Results

Twelve studies (234,129 patients) were included. Pooled sensitivity/specificity were 0.679/0.763 for SI (5 studies, AUC 0.747), 0.788/0.801 for RTS (6 studies, AUC 0.852), and 0.788/0.796 for ISS (9 studies, AUC 0.855). In the six studies reporting both RTS and ISS, a paired bivariate comparison found no significant difference in diagnostic accuracy (likelihood-ratio test, p = 0.91; within-study sensitivity OR 1.59, 95% CI 0.82-3.07; specificity OR 0.89, 95% CI 0.55-1.45).

Conclusion

RTS and ISS did not differ significantly in a formal paired comparison, and neither tool, alone, reliably rules in or out death at realistic trauma prevalence. SI, RTS and ISS should be understood as serving different, complementary roles across the trauma timeline - SI and RTS at the point of acute triage, ISS as a later anatomical benchmark - rather than as competing predictors to be ranked against one another.