Within-year Exertional Heat Illness Incidence in U.S. Army Soldiers, 2008-2012.

摘要

The incidence of and risk factors for exertional heat illness (EHI) in the US Army have been well documented. The heat season, when the risk of EHI is highest and application of risk mitigation procedures is mandatory, has been arbitrarily defined as 1 May through 30 September. The proportion of EHI that occur outside of the traditional heat season is unknown. Additionally, it is unknown if the heat season definition is appropriate. Purpose: To determine the proportion of EHI that occur within the traditional definition of the heat season at select US Army installations and to examine whether the heat season definition requires revision, Army-wide or on an installation-specific basis. Methods: The 10 US Army installations with the highest frequency of EHI from 2008-2012 were identified and used for analysis. In- and out-patient EHI data (ICD-9-CM codes 992-992.9, first or second diagnoses only) were obtained from the Defense Medical Surveillance System. The summer heat season was operationally defined as 1 May through 30 September; the proportional distribution of EHI within the heat season, overall and by installation was determined. In order to assess the relation between ambient weather conditions and EHI incidence, weather data were downloaded from the National Centers for Environmental Information website and overlaid with weekly EHI incidence plots. Piecewise segmental regression analysis was conducted in order to determine the beginning and end of the heat season for all locations combined and by individual location. Results: During the investigation period there were 7,827 EHIs, 79% of which occurred during the heat season. However, between locations there was considerable variability in within heat season EHI frequency, ranging from 70.1% at Ft Bragg to 95.3% at Ft Sill. The locations with the greatest EHI frequency were Ft Bragg (n=2,129), Ft Benning (n=1,560), and Ft Jackson (n=1,538).