Sex Differences In The Clinical Sequelae Of Exertional Heat Stroke In Military Servicemembers

Abstract

Exertional heat stroke (EHS) represents a significant source of morbidity and mortality for the military and other occupational and athletic populations. EHS patients tend to present with elevated biomarkers of acute liver and kidney injury, rhabdomyolysis, and altered hematological parameters. However, little is know about how men and women may respond differently to EHS, in terms of clinical severity and/or biochemical responses. PURPOSE: The aim of this study was to characterize clinical and biochemical differences between male and female servicemembers immediately following an EHS episode. METHODS: We performed a retrospective analysis of EHS patient records in all US military personnel (41% between 20-24 years old) from 2008-2014 using the Military Health Systems Data Repository. We compared diagnoses of organ failure during the course of treatment and clinical laboratory markers of end organ damage. Sex differences in clinical outcomes are presented with odds ratios, and biomarker differences are presented as the median difference with 95% confidence intervals in brackets. RESULTS: A total of 2,529 EHS cases were recorded with 9.8% [8.7, 11.2] occuring in women. Per patient treatment cost was lower in women by $1110 [620, 1647]. Men were 2.35 [1.6, 3.58] times more likely to experience renal failure (p = < .001). Blood urea nitrogen, (difference = -121.05 mg/dL [41.9, 182.28]), myoglobin (difference = 3 ng/mL [2, 4]), aspartate transaminase (difference = 7 units/L [1, 14]), and alanine transaminase (difference = 13 units/L [8.5, 15.92]) were elevated in men (all p < .01). Platelet count was also lower in men compared to women (difference = -22.14*103 per uL [-39.25, -2.99], p = 0.03). CONCLUSION: Female servicemembers appear to have a slightly less severe response to EHS compared to their male counterparts. In particular, renal failure was more common, and numerous markers of end-organ damage (hepatic, renal, and cardiovascular) were more likely to be elevated immediately following EHS in men. Supported by USAMRDC; author views not official US Army or DoD policy.