The Accuracy of GAP and MGAP Scoring Systems in Predicting Mortality in Trauma; a Diagnostic Accuracy Study

Trauma scoring systems help physicians and nurses to be informed of injuries to a patient and assist their decision making in the cases of trauma and importantly prediction of their outcome and prognosis. 

This study aimed to compare the accuracy of GAP and MGAP scoring systems as predictors of mortality in trauma patients. 

This diagnostic accuracy study was conducted amongst 1861 trauma patients admitted to Rajaee Hospital in Shiraz, Iran, during 2017. The data on demographic features were extracted from the patients’ records. Then, trauma scoring systems including injury severity score (ISS), GAP, MGAP, and Glasgow coma scale (GCS) were compared to evaluate their accuracy in predicting mortality. Area under the receiver operating characteristic (ROC) curve was used to evaluate the accuracy of different trauma scoring systems and detect the sensitivity and specificity in order to predict status of discharge after 24 hours. 

Based on the results, the area under the ROC curve was 0.8 for GCS. Moreover, Area Under Curve (AUC) of GAP was 0.91 and amongst different values, GAP value of ≤18 was selected as the cut-off point, since it exhibited the best sensitivity and specificity (72.99 and 95.52, respectively). In addition, the area under the ROC curve was 0.9 for MGAP, and value of ≤23 was selected as the cut-off point because it showed the best sensitivity and specificity (81.04 and 87.70, respectively). Additionally, AUC of ISS was 0.88. 

Both GAP and MGAP methods were able to appropriately predict mortality and were not significantly different; hence, both can be used for the right triage of patients and to predict the severity of injuries and subsequent mortality. Moreover, GAP and ISS had the best specificity and sensitivity, respectively.