Prediction of intra-hospital mortality after severe trauma: which pre-hospital score is the most accurate?

Computing trauma scores in the field allows immediate severity assessment for appropriate triage. Two pre-hospital scores can be useful in this context: the Triage-Revised Trauma Score (T-RTS) and the Mechanism, Glasgow, Age and arterial Pressure (MGAP) score. The Trauma Revised Injury Severity Score (TRISS), not applicable in the pre-hospital setting, is the reference score to predict in-hospital mortality after severe trauma. The aim of this study was to compare T-RTS, MGAP and TRISS in a cohort of consecutive patients admitted in the Trauma system of the Northern French Alps(TRENAU). From 2009 to 2011, 3260 patients with suspected severe trauma according to the Vittel criteria were included in the TRENAU registry. All data necessary to compute T-RTS, MGAP and TRISS were collected in patients admitted to one level-I, two level-II and ten level-III trauma centers. The primary endpoint was death from any cause during hospital stay. Discriminative power of each score to predict mortality was measured using receiver operating curve (ROC) analysis. To test the relevancy of each score for triage, we also tested their sensitivity at usual cut-offs. We expected a sensitivity higher than 95% to limit undertriage. The TRISS score showed the highest area under the ROC curve (0.95 [CI 95% 0.94-0.97], p<0.01). Pre-hospital MGAP score had significantly higher AUC compared to T-RTS (0.93 [CI 95% 0.91-0.95] vs 0.86 [CI 95% 0.83-0.89], respectively, p<0.01). MGAP score<23 had a sensitivity of 88% to detect mortality. Sensitivities of T-RTS<12 and TRISS<0.91 were 79% and 87%, respectively. Pre-hospital calculation of the MGAP score appeared superior to T-RTS score in predicting intra-hospital mortality in a cohort of trauma patients. Although TRISS had the highest AUC, this score can only be available after hospital admission. These findings suggest that the MGAP score could be of interest in the pre-hospital setting to assess patients' severity. However, its lack of sensitivity indicates that MGAP should not replace the decision scheme to direct the most severe patients to level-I trauma center