Abstract: Three trials met the inclusion criteria. Two trials (n = 20,451) assessed the effect of TXA. The larger of these (CRASH-2, n = 20,211) was conducted in 40 countries and included patients with a variety of types of trauma; the other (n = 240) restricted itself to those with traumatic brain injury (TBI) only. One trial (n = 77) assessed aprotinin in participants with major bony trauma and shock. The pooled data show that antifibrinolytic drugs reduce the risk of death from any cause by 10% (RR 0.90, 95% CI 0.85 to 0.96; P = 0.002) (quality of evidence: high). This estimate is based primarily on data from the CRASH-2 trial of TXA, which contributed 99% of the data. There is no evidence that antifibrinolytics have an effect on the risk of vascular occlusive events (quality of evidence: moderate), need for surgical intervention or receipt of blood transfusion (quality of evidence: high). There is no evidence for a difference in the effect by type of antifibrinolytic (TXA versus aprotinin) however, as the pooled analyses were based predominantly on trial data concerning the effects of TXA, the results can only be confidently applied to the effects of TXA. The effects of aprotinin in this patient group remain uncertain. There is some evidence from pooling data from one study (n = 240) and a subset of data from CRASH-2 (n = 270) in patients with TBI which suggest that TXA may reduce mortality although the estimates are imprecise, the quality of evidence is low, and uncertainty remains. Stronger evidence exists for the possibility of TXA reducing intracranial bleeding in this population. TXA safely reduces mortality in trauma patients with bleeding without increasing the risk of adverse events.  TXA should be given as early as possible and within three hours of injury, as further analysis of the CRASH-2 trial showed that treatment later than this is unlikely to be effective and may be harmful. Although there is some promising evidence for the effect of TXA in patients with TBI, substantial uncertainty remains. Two ongoing trials being conducted in patients with isolated TBI should resolve these remaining uncertainties.

Plain-language summary: Two trials assessed the effect of TXA in patients aged 16 and over. The largest (n = 20,211) involved patients suffering from a variety of types of trauma, and the other (n = 240) only those who had suffered traumatic brain injury. Results The trial assessing the effect of aprotinin was too small to provide reliable data. Results for TXA suggest that, when given early, TXA reduces the risk of death compared to patients who do not receive TXA without increasing the risk of side effects. However, there is still some uncertainty about the effect of TXA in patients who have bleeding inside the brain from a head injury, but are not bleeding from injuries elsewhere. It is possible that the effects of TXA are different in this specific patient group. We have found two ongoing trials that are trying to answer this question. The authors of this review conclude that TXA can safely reduce death in trauma patients with bleeding and should be given as soon as possible after injury. However, they cannot conclude whether or not TXA is also effective in patients with traumatic brain injury with no other trauma, until the ongoing trials have been completed. Quality of the evidence Evidence for important outcomes including mortality, need for further surgery and blood transfusion, came from high-quality evidence, meaning we have confidence in the findings. There was moderate-quality evidence for important adverse events including vascular occlusive events (including heart attacks, deep vein thrombosis, stroke and pulmonary embolism).