By Eleanor McDermid, Senior medwireNews Reporter
Tranexamic acid confers survival benefits in trauma patients irrespective of their baseline mortality risk, shows a prespecified analysis of CRASH-2.
Trauma protocols tend to focus on the most high-risk patients, but the findings show that tranexamic acid "should not be restricted to the most severely injured," study author Ian Roberts (London School of Hygiene and Tropical Medicine, London, UK) and team write in the BMJ.
And although tranexamic acid is given to mitigate traumatic bleeding, the benefits do not appear to come at an increased risk for thrombotic events. Indeed, the analysis shows a significant 31% reduction in the risk for fatal and nonfatal thrombotic events, a 42% reduction in the risk for arterial thrombotic events, and no difference in the risk for venous thrombotic events among patients given tranexamic acid versus those given placebo.
"Clinical concern about an increased risk of ischaemic cardiac events might be a reason to give rather than to withhold tranexamic acid," say Roberts et al. "It is worth noting that trials of tranexamic acid in patients undergoing cardiac surgery, a group at high risk of cardiac events, provide no evidence of any increased risk."
The team's analysis included 13,273 trauma patients from CRASH-2 (Clinical Randomisation of an Antifibrinolytic in Significant Haemorrhage 2) who were treated within 3 hours of injury. Patients assigned to receive tranexamic acid were given a loading dose of 1 g over 10 minutes followed by an infusion of 1 g over 8 hours.
Overall, tranexamic acid treatment resulted in a 15% reduction in mortality risk relative to placebo treatment, with no evidence of heterogeneity according to patients' baseline mortality risk (calculated with the CRASH-2 prognostic model). The sizes of the reduction were 22%, 17%, 20%, and 23% at baseline risk levels of less than 6%, 6-20%, 21-50%, and more than 50%, respectively.
However, the team stresses that absence of evidence "should not be taken as evidence of absence," noting that the confidence interval was particularly wide for the lowest-risk group.
But Roberts et al say that, assuming this consistent survival benefit to be true, had tranexamic acid been given to the more than 13,000 patients in the UK Trauma and Audit Research Network within 3 hours of injury, it could have prevented 17% of deaths in patients who had a baseline mortality risk below 6% or above 50%, and about a third of deaths in patients with an intermediate risk.
A very high proportion of these patients had a less than 10% mortality risk at baseline, meaning that the largest absolute benefits of tranexamic acid would have occurred among low-risk patients. The researchers also note that large absolute benefits are to be expected among older patients, "who at any given level of severity of injury have a higher baseline risk of death from haemorrhage and thrombotic events."
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