Tranexamic acid in trauma care : who should be treated, when and where?

Introduction: Early tranexamic acid (TXA) treatment reduces bleeding deaths in trauma patients. Guidelines recommend the use of TXA for trauma patients who are bleeding or who are at risk of significant haemorrhage within 3 hours of the injury. However, many trauma patients who might benefit from TXA are either not treated or not treated soon enough. Early identification of haemorrhage is challenging and could explain this poor implementation. The purpose of the thesis is to determine who should be treated, when and where. Methods: First, I developed and validated a prognostic model to predict traumatic death due to bleeding using multivariate logistic regression. Second, I conducted an IPD meta-analysis of randomised trials to assess whether the effectiveness of TXA varies by baseline risk of death due to bleeding. Third, I assessed the health impact of TXA treatment in terms of deaths avoided using the Trauma Audit and Research Network registry. Finally, I developed and validated a simple score (BATT score) that could be used by paramedics to identify patient sat risk of haemorrhage and suggested treatment criteria that maximise the number of deaths avoided with TXA. Results: The relative risk reduction with TXA did not appear to vary by baseline risk. Treating all major trauma patients prior to hospital arrival avoided more deaths and with a lower number needed to treat than with in-hospital treatment. The BATT score had a high discrimination (C-stat=0.90; 95%confidence interval 0.89-0.91). Treating patients with a BATT score ≥2 (60% of major trauma patients)would allow to avoid many deaths compared to current practice. Conclusion : TXA should be given at the scene of the injury. It should be administered to a wide range of trauma patients and not only restricted to the most severely injured. A BATT score≥2 represents a simple guidance for paramedics to initiate TXA treatment.