An Analysis of the Shock Index and Pulse Pressure as a Predictor for Massive Transfusion and Death in US and Coalition Iraq and Afghanistan.

Among combat casualties with survivable injuries, the most common cause of mortality is massive hemorrhage. The objective of this study was to identify the accuracy of shock index (SI) and pulse pressure (PP) for predicting receipt of massive transfusion and death on the battlefield. The study searched the Department of Defense Trauma Registry from January 2007 to August 2016 using a series of procedural codes to identify casualties which has been previously described. This is a secondary analysis of casualties analyzing SI. This study analyzed using receiver operating characteristic (ROC) and regression analyses. Within that dataset, there were 15,540 that were US Forces (75.1%), Coalition Forces (14.5%) or contractors (10.3%)-of which, 1,261 (7.9%) underwent massive transfusion. On ROC analyses for SI, this study found an overall optimal threshold at 0.91 with an area under the curve (AUC) of 0.89 with a sensitivity of 0.81 and specificity of 0.87 for predicting massive transfusion. The study found an optimal threshold of 0.91 with an AUC of 0.76 with a sensitivity of 0.67 and specificity of 0.82 for predicting death. On ROC analyses for PP, the study found an overall optimal threshold at 48 with an AUC of 0.71 with a sensitivity of 0.56 and specificity of 0.76 for predicting massive transfusion. The study found an optimal threshold of 44 with an AUC of 0.75 with a sensitivity of 0.60 and specificity of 0.82 for predicting death. SI and PP may accurately predict receipt of massive transfusion and of mortality in a combat casualty population.