Abstract

BACKGROUND No FDA-approved medication improves outcomes following traumatic brain injury (TBI). A forthcoming clinical trial that evaluated the effects of two prehospital tranexamic acid (TXA) dosing strategies compared with placebo demonstrated no differences in thromboelastography (TEG) values. We proposed to explore the impact of TXA on markers of coagulation and fibrinolysis in patients with moderate to severe TBI. METHODS Data were extracted from a placebo-controlled clinical trial in which patients ≥15 years old with TBI (Glascow Coma Scale 3-12) and systolic blood pressure ≥90 mmHg were randomized prehospital to receive placebo bolus/placebo infusion (Placebo), 1 gram (g) TXA bolus/1g TXA infusion (Bolus Maintenance [BM]); or 2g TXA bolus/placebo infusion (Bolus Only [BO]). TEG was performed and coagulation measures including prothrombin time (PT), activated partial thromboplastin time (aPTT), international ratio (INR), fibrinogen, D-dimer, plasmin anti-plasmin (PAP), thrombin anti-thrombin (TAT), tissue plasminogen activator (tPA), and plasminogen activator inhibitor-1 (PAI-1) were quantified at admission and six hours later. RESULTS Of 966 patients receiving study drug, 700 had labs drawn at admission and six hours later. There were no statistically significant differences in TEG values, including LY30, between groups (p>0.05). No differences between PT, aPTT, INR, fibrinogen, TAT, tPA, and PAI-1 were demonstrated across treatment groups. Concentrations of D-dimer in TXA treatment groups were less than placebo at six hours (p<0.001). Concentrations of PAP were less in TXA treatment groups than placebo on admission (p<0.001) and six hours (p=0.02). No differences in D-dimer and PAP were observed between BM and BO. CONCLUSION While D-dimer and PAP levels reflect a lower degree of fibrinolysis following prehospital administration of TXA when compared to placebo in a large prehospital trial of patients with TBI, TEG obtained on admission and six hours later did not demonstrate any differences in fibrinolysis between the two TXA dosing regimens and placebo. LEVEL OF EVIDENCE III; Diagnostic.

Abstract

IMPORTANCE Traumatic brain injury (TBI) is the leading cause of death and disability due to trauma. Early administration of tranexamic acid may benefit patients with TBI. OBJECTIVE To determine whether tranexamic acid treatment initiated in the out-of-hospital setting within 2 hours of injury improves neurologic outcome in patients with moderate or severe TBI. DESIGN, SETTING, AND PARTICIPANTS Multicenter, double-blinded, randomized clinical trial at 20 trauma centers and 39 emergency medical services agencies in the US and Canada from May 2015 to November 2017. Eligible participants (N = 1280) included out-of-hospital patients with TBI aged 15 years or older with Glasgow Coma Scale score of 12 or less and systolic blood pressure of 90 mm Hg or higher. INTERVENTIONS Three interventions were evaluated, with treatment initiated within 2 hours of TBI: out-of-hospital tranexamic acid (1 g) bolus and in-hospital tranexamic acid (1 g) 8-hour infusion (bolus maintenance group; n = 312), out-of-hospital tranexamic acid (2 g) bolus and in-hospital placebo 8-hour infusion (bolus only group; n = 345), and out-of-hospital placebo bolus and in-hospital placebo 8-hour infusion (placebo group; n = 309). MAIN OUTCOMES AND MEASURES The primary outcome was favorable neurologic function at 6 months (Glasgow Outcome Scale-Extended score >4 [moderate disability or good recovery]) in the combined tranexamic acid group vs the placebo group. Asymmetric significance thresholds were set at 0.1 for benefit and 0.025 for harm. There were 18 secondary end points, of which 5 are reported in this article: 28-day mortality, 6-month Disability Rating Scale score (range, 0 [no disability] to 30 [death]), progression of intracranial hemorrhage, incidence of seizures, and incidence of thromboembolic events. RESULTS Among 1063 participants, a study drug was not administered to 96 randomized participants and 1 participant was excluded, resulting in 966 participants in the analysis population (mean age, 42 years; 255 [74%] male participants; mean Glasgow Coma Scale score, 8). Of these participants, 819 (84.8%) were available for primary outcome analysis at 6-month follow-up. The primary outcome occurred in 65% of patients in the tranexamic acid groups vs 62% in the placebo group (difference, 3.5%; [90% 1-sided confidence limit for benefit, -0.9%]; P = .16; [97.5% 1-sided confidence limit for harm, 10.2%]; P = .84). There was no statistically significant difference in 28-day mortality between the tranexamic acid groups vs the placebo group (14% vs 17%; difference, -2.9% [95% CI, -7.9% to 2.1%]; P = .26), 6-month Disability Rating Scale score (6.8 vs 7.6; difference, -0.9 [95% CI, -2.5 to 0.7]; P = .29), or progression of intracranial hemorrhage (16% vs 20%; difference, -5.4% [95% CI, -12.8% to 2.1%]; P = .16). CONCLUSIONS AND RELEVANCE Among patients with moderate to severe TBI, out-of-hospital tranexamic acid administration within 2 hours of injury compared with placebo did not significantly improve 6-month neurologic outcome as measured by the Glasgow Outcome Scale-Extended. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT01990768.