Am J Emerg Med. 2019 May 31 Epub ahead of print

# Tranexamic acid in traumatic hemorrhage: Evidence argues for a prehospital administration.

Boutonnet M, Osorio Cajes G, Pasquier P, Ausset S

We read with interest the study of El-Menyar et al. comparing the mortality, thromboembolic events (VTE) and need for blood transfusion in trauma patients receiving or not receiving prehospital tranexamic acid (TXA). In this 21-months comparative retrospective study, 204 trauma patients were compared after 1:1 matching. 102 patients receiving TXA were matched to 102 patients not receiving TXA but transfused in the 4 h following admission. Neither the overall mortality rate [OR 0.78 (95% CI 0.42–1.45)], nor the VTE [OR 2.0 (CI 95% 0.37–11.40)] differed between the two groups. However, the median amount of blood transfusion was greater in the control group [8 units (range 1–40) vs 3 (range 0–40), p = 0.01] as well as the use of massive blood transfusion [OR 0.35 (95% CI 0.19–0.67)], defined as ten or more units of red blood cells over a 24 hour period or >40 ml/kg packed-red blood cells (PRBC) in 2 h or less. We fully agree with the authors when they state that prehospital TXA administration reduced the need for massive transfusion and the amount of blood transfusion. The authors pointed out two limitations. First the study was probably underpowered for mortality. Second, TXA was also administered to non-coagulopathic patients or to patients without active bleeding. Interestingly, in a recent study, conducted in a comparable mature trauma care system we compared the mortality of patients receiving or not, early administration of TXA (prehospital or in emergency room (ER)) . We believe that our study addresses these two limitations. We included 470 trauma patients receiving TXA and 327 not receiving TXA managed in the six Level-1 trauma centers in Paris area. After propensity score weighting, mortality was lowered by the use of TXA in patients requiring PRBC transfusion in the ER [hazard ratio 0.3 (CI 95% 0.3–0.6)] but not in patients who did not require emergent transfusion. Moreover, in a German retrospective study, including 516 trauma patients, prehospital administration of tranexamic acid in trauma patients was associated with significant improvement in early mortality (24 h mortality 5.8% vs 12.4%, p = 0.01). These results enhanced the conclusions of the CRASH-2 study which exhibited a 10% of mortality improvement with the early empiric use of TXA in trauma patients with (or at risk of) severe hemorrhage. Thus, despite the respective limitations of these studies, the preponderance of the evidence suggests that prehospital or early administration of TXA in mature trauma care systems improve mortality in the most hemorrhagic of the trauma patients.

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