Correlation Between the Revised Trauma Score and Injury Severity Score: Implications for Prehospital Trauma Triage

Prehospital triage of the seriously injured patient is fraught with challenges, and trauma scoring systems in current triage guidelines warrant further investigation. The primary objective of this study was to assess the correlation of the physiologically based Revised Trauma Score (RTS) and MGAP score (mechanism of injury, Glasgow Coma Scale, age, blood pressure) with the anatomically based Injury Severity Score (ISS). The secondary objectives for this study were to compare the accuracy of the MGAP score and the RTS for the prediction of in-hospital mortality for trauma patients.

This study was a retrospective cohort including 10 years of patient data in a large single-center trauma registry at a primary adult resource center (Level I) for trauma patients. Participants included adults (age ≥18 years). The primary outcome measure was injury severity (measured by ISS) and a secondary analysis compared the RTS and MGAP for the prediction of patient mortality. Descriptive statistics were used to describe the cohort and correlation methods were employed. Each score's accuracy for the prediction of mortality was calculated using the area under receiver operating characteristic (AUROC) curves.

In total, 43,082 trauma patient records were reviewed; 32,798 patients had complete RTS data available and 32,371 patients had complete data available for MGAP analyses. The correlation between scene RTS and ISS was poor (-.29), as was the correlation between MGAP and ISS (-.28). For the prediction of mortality, admission MGAP demonstrated the highest sensitivity and specificity for mortality (AUROC 0.96; 95% CI, 0.95-0.96).

While elements of the RTS remain the first criterion recommended to quantify the totality of physiological injury severity, the composite RTS score derived from this system correlates poorly with actual anatomical injury severity. The MGAP scoring system demonstrated higher sensitivity and specificity for mortality but was not superior to the RTS for predicting anatomical injury severity. In the future development of national and international field triage guidelines for trauma patients, the findings from this study may be considered in order to improve the accuracy of prehospital triage. The findings in this analysis complement a growing body of evidence that suggests that MGAP may be a superior and more easily calculable prehospital scoring system for the prediction of mortality in trauma patients.