Characterization of acute coagulopathy and sexual dimorphism after injury: Females and coagulopathy just do not mix

BACKGROUND: Acute traumatic coagulopathy (ATC) predicts poor outcome after injury. Females have been demonstrated to be hypercoagulable early in the posttrauma period. It remains unclear whether presence of ATC alters sex-based outcomes after injury. This study's objective was to characterize the sex dimorphism after severe injury in the presence and absence of ATC. METHODS: Data were obtained from a multicenter prospective cohort study of patients with blunt trauma and hemorrhagic shock. ATC was defined as arrival international normalized ratio (INR) of greater than 1.5. Cox regression was used to determine the independent risks of mortality and multiple-organ failure associated with sex in subjects with ATC and without (non-ATC) while controlling for important confounders. The sex mortality differences were characterized over time to determine at what point after injury any differential risks diverge. RESULTS: Of 2,007 enrolled subjects, 1,877 had an arrival INR with 439(23%) having ATC. There was no difference in incidence of ATC across sex (24% vs. 23%; p = 0.95). In the ATC group, no difference in Injury Severity Score, arrival INR, base deficit, temperature, or 24-hour blood requirements were found across sex. Cox hazard regression revealed that sex was not associated with mortality in non-ATC patients (hazard ratio, 0.94; 95% confidence interval, 0.6-1.5). Female sex was independently associated with mortality only in the ATC group (hazard ratio, 2.04; 95% confidence interval, 1.1-3.9;p = 0.03). These mortality risk differences across sex diverged within the first 24 hours after injury. CONCLUSION: An exaggerated sex dimorphism exists for patients with ATC, with females demonstrating a twofold higher independent risk of mortality. These differential mortality risks across sex diverge early after injury, suggesting that they may be caused by an ongoing hemorrhage. Females who present with ATC at admission have a significantly greater risk of poor outcome. Further studies are warranted to explore the mechanisms responsible for sex dimorphism in the setting of ATC. (J Trauma Acute Care Surg. 2012;73: 1395-1400. Copyright (C) 2012 by Lippincott Williams & Wilkins) LEVEL OF EVIDENCE: Prognostic study, level H.