Burns to the genitalia, perineum, and buttocks increase the risk of death among U.S. service members sustaining combat-related burns in Iraq and Afghanistan.

PURPOSE: Among service members injured in Iraq and Afghanistan, to determine the risk of mortality associated with combat-related burns to the genitalia, perineum, and buttocks.

MATERIALS AND METHODS: The prospectively maintained burn registry from the United States Army Institute of Surgical Research was retrospectively reviewed to identify all service members with combat-related burns sustained in Iraq and Afghanistan from March 2003 to October 2013. The two primary risk factors of interest were (1) any burn to the genitals, perineum, and/or buttocks (PB) and (2) burns involving the entire perineal, genital, and buttock region (complete PB). Cox proportional hazard models were used to estimate the risk of mortality for both primary risk factors, and adjusted for severe non-burn-related trauma, percent of burn over total body surface area (TBSA), inhalational injury, time to urinary tract infection, and time to bacteremia. A post-hoc analysis was performed to explore the potential effect modification of TBSA burned on the relationship between PB and mortality.

RESULTS: Among the 902 U.S. service members with combat-related burns sustained during the study period, 226 (25.0%) had involvement of the genitalia, perineum, and/or buttocks. Complete PB was associated with a crude risk of mortality (HR: 5.3; 2.9-9.7), but not an adjusted risk (HR=1.8; 0.8-4.0). However, TBSA burned was identified as a potential negative effect modifier. Among patients with burns <60% TBSA, sustaining a complete PB conferred an adjusted risk of death (HR=2.7; 1.1-6.8). Further, patients with a perineal burn had a five-fold increased incidence of bacteremia. In adjusted models, each event of bacteremia increased the risk of mortality by 92% (HR 1.92; 1.39-2.65). Perineal burns were associated with a two-fold increased incidence of severe non-burn related trauma that also doubled mortality risk in adjusted models (HR 2.29; 1.23-4.27).

CONCLUSIONS: Among those with relatively survivable combat-related burns (<60% TBSA), genital/perineal/buttock involvement increases the risk of death. Bacteremia may account for part of this increased risk, but does not fully explain the independent risk associated with perineal burns.