Research article
Exertional Heat-Related Injuries Treated in Emergency Departments in the U.S., 1997–2006

https://doi.org/10.1016/j.amepre.2010.09.031Get rights and content

Background

Exertional heat-related injuries are a risk to all physically active individuals in warm or hot environments. Unlike classic heat-related injury, exertional heat-related injuries do not require extreme ambient temperatures to cause injury. Still, exertional heat-related injuries, including heat cramps, heat syncope, heat exhaustion, heat stress, and heat stroke, can result in injuries causing a range of outcomes from minimal discomfort to death.

Purpose

The purpose of this paper was to describe the epidemiology of exertional heat-related injuries treated in U.S. emergency departments.

Methods

A retrospective analysis was conducted using data from the National Electronic Injury Surveillance System of the U.S. Consumer Product Safety Commission for all ages from 1997 through 2006. Data provided by the National Electronic Injury Surveillance System were used to calculate national estimates of exertional heat-related injuries. Trends of exertional heat-related injuries over time were analyzed using linear regression.

Results

Nationally, an estimated 54,983 (95% CI=39995, 69970) patients were treated in U.S. emergency departments for exertional heat-related injuries from 1997 to 2006. The number of exertional heat-related injuries increased significantly from 3192 in 1997 to 7452 in 2006 (p=0.002), representing a 133.5% increase. The overall exertional heat-related injury rate per 100,000 U.S. population more than doubled from 1.2 in 1997 to 2.5 in 2006 (p=0.005). Patients aged ≤19 years accounted for the largest proportion of exertional heat-related injuries (47.6%). The majority of exertional heat-related injuries were associated with performing a sport or exercising (75.5%) and yard work (11.0%). The majority of patients (90.4%) were treated and released from the emergency department. Patients aged ≤19 years sustained a larger proportion of sports and recreation exertional heat-related injuries, whereas patients aged 40–59 years and ≥60 years sustained a larger proportion of exertional heat-related injuries from yard work.

Conclusions

This study confirms that although there is a risk of exertional heat-related injury among all physically active individuals, sports pose a specific risk for people of all ages especially among children and adolescents playing football. Many “everyday” activities such as yard work and home maintenance also pose risks of exertional heat-related injury, particularly to those aged ≥40 years. Further research on risk factors of exertional heat-related injuries during home maintenance and yard work as well as appropriate prevention practices is needed.

Introduction

The human body is built to efficiently distribute heat and lose excess heat to the surrounding environment. When the body's ability to regulate temperature is impeded, heat-related injury can occur. There are several types of heat-related injury, including heat cramps, heat syncope, heat exhaustion, heat stress, and heat stroke.1 The outcomes can range from minimal discomfort and self-limiting symptoms to death. Heat exhaustion is a warning that the body is getting too hot, and it is often caused by the body's loss of water and salt. Signs of heat exhaustion include thirst, giddiness, weakness, loss of coordination, nausea, sweating profusely, and cold and clammy skin with normal body temperature and normal or raised pulse. Heat stress occurs when a strain is placed on the body as a result of elevated body temperature. Heat stoke occurs when a person's core temperature rises above 40.6°C (105°F) because of exposure to increased temperature or excessive exertion. Heat stroke is often accompanied by hot, dry skin and central nervous system abnormalities such as delirium, convulsions, or coma. Heat cramps are muscle spasms following strenuous activity; symptoms include moist and cool skin, normal or slightly raised pulse, and normal body temperature.2 Several risk factors can affect the body's thermoregulatory mechanisms, including ambient air temperature and humidity, clothing, medications, dehydration, acute illness, poor physical condition, and heat acclimatization.3, 4

Attention to heat-related injuries has increased considerably in the past few decades because of excess mortality during extreme heat events in the U.S. and Europe.5, 6 This classic category of heat-related injury that occurs during heat waves mostly affects the very young, old, or debilitated.1 A second category of heat-related injury, exertional heat-related injury (EHI), is a risk to all physically active individuals in warm or hot environments and does not necessarily require extreme ambient temperatures to cause injury. Exertional heat-related injury has also gained national attention from high-profile deaths in athletes,7 and many sports associations have released position statements on heat illness.8, 9, 10

The existing literature on EHI focuses mainly on athletes,11, 12, 13 military personnel,14, 15 or specific occupations.16, 17 There has been extensive research on mitigating the risk factors of EHI in these populations18, 19 However, there is a paucity of epidemiologic research on EHI in the general population. There is a particular dearth in information on EHI in people participating in “everyday” activities, such as gardening, washing the car, mowing the lawn, or leisure recreation. The purpose of this paper was to describe to the epidemiology of all EHIs treated in U.S. emergency departments from 1997 through 2006.

Section snippets

Data Source

The National Electronic Injury Surveillance System (NEISS) of the U.S. Consumer Product Safety Commission (CPSC) is a stratified probability sample of ∼100 U.S. hospital emergency departments, including seven children's hospitals, representing 6100 hospitals with at least six beds and a 24-hour emergency department.20 There are two military hospitals included in the NEISS; however, injuries to active duty military personnel are not in-scope for the CPSC and are considered work-related injuries

Results

Nationally, an estimated 54,983 (95% CI=39995, 69970) patients were treated in U.S. emergency departments for EHIs from 1997 through 2006. Patients who sustained EHIs had a mean age of 30.8 years (SD=20.5 years, range=15 months–90 years), and 71.9% were male. Patients who were aged ≤19 years accounted for the largest proportion of injuries (47.6%). The majority (66.1%) of EHIs occurred during June, July, and August. The majority of EHIs were associated with sports or exercise (75.5%) and yard

Discussion

To our knowledge, this was the first study to estimate EHI treated in U.S. emergency departments among the general population based on a national sample. An estimated 54,983 EHIs were treated in U.S. emergency departments during the 10-year study period. This increase does not appear to be related to increasing seasonal temperatures in NEISS cities, which showed no pattern and had no significant increase over the study period. However, more detail climate data, including fluctuations in extreme

Conclusion

Exertional heat-related injuries are preventable. Simple awareness messages on EHI prevention should include ensuring adequate hydration, taking adequate rest breaks during physical activity, and scheduling the physical activity during cooler periods of the day, such as the morning or evening. To date, most EHI awareness and prevention campaigns have targeted athletes. The current findings support this focus; however, they also indicate a need for prevention campaigns for EHIs that occur during

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