Prehospital tranexamic acid is associated with a survival benefit without an increase in complications: Results of two harmonized randomized clinical trials.

Introduction: Recent randomized clinical trials have demonstrated that prehospital tranexamic acid (TXA) administration following injury is safe and improves survival. However, the effect of prehospital TXA on adverse events, transfusion requirements, and any dose-response relationships require further elucidation.

Methods: A secondary analysis was performed using harmonized data from two large, double-blinded, randomized prehospital TXA trials. Outcomes, including 28-day mortality, pertinent adverse events, and 24-hour red cell transfusion requirements, were compared between TXA and placebo groups. Regression analyses were used to determine the independent associations of TXA after adjusting for study enrollment, injury characteristics, and shock severity across a broad spectrum of injured patients. Dose-response relationships were similarly characterized based upon grams of prehospital TXA administered.

Results: A total of 1,744 patients had data available for secondary analysis and were included in the current harmonized secondary analysis. The study cohort had an overall mortality of 11.2% and a median Injury Severity Score of 16 (interquartile range, 5-26). Tranexamic acid was independently associated with a lower risk of 28-day mortality (hazard ratio, 0.72; 95% confidence interval [CI], 0.54-0.96; p = 0.03). Prehospital TXA also demonstrated an independent 22% lower risk of mortality for every gram of prehospital TXA administered (hazard ratio, 0.78; 95% CI, 0.63-0.96; p = 0.02). Multivariable linear regression verified that patients who received TXA were independently associated with lower 24-hour red cell transfusion requirements ( β= - 0.31; 95% CI, -0.61 to -0.01; p = 0.04) with a dose-response relationship ( β= - 0.24; 95% CI, -0.45 to -0.02; p = 0.03). There was no independent association of prehospital TXA administration on thromboembolism, seizure, or stroke.

Conclusion: In this secondary analysis of harmonized data from two large randomized interventional trials, prehospital TXA administration across a broad spectrum of injured patients is safe. Prehospital TXA is associated with a significant 28-day survival benefit and lower red cell transfusion requirements at 24 hours and demonstrates a dose-response relationship.

Level of evidence: Therapeutic/Care Management; Level III.