The effect of extreme heat on health has become a growing public health concern due to climate change. We aimed to examine the epidemiological patterns of hospital-based emergency department (ED) visits for heat stroke in the United States.
We analyzed data from the 2009 and 2010 Nationwide Emergency Department Sample, the largest ED data system sponsored by the Agency for Healthcare Research and Quality. ED visits for heat stroke were identified by screening the recorded diagnoses using the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) code 992.0. Annual incidence rates of ED visits for heat stroke were computed according to demographic characteristics and geographic regions. In 2009 and 2010, there were an estimated 8,251 ED visits for heat stroke in the United States, yielding an annual incidence rate of 1.34 visits per 100,000 population (95% Confidence Interval [CI] = 1.23-1.45). Significantly higher incidence rates were found in males (1.99 per 100,000; 95% CI = 1.82-2.16), adults aged ≥ 80 years (4.45 per 100,000; 95% CI = 3.73-5.18), and residents living in the southern region (1.61 per 100,000; 95% CI = 1.43-1.79). The majority (63.1%) of ED visits for heat stroke occurred during the summer months of June, July and August. Over one-half (54.6%) of the ED visits for heat stroke required hospitalization and 3.5% of the patients died in the ED or hospital.
Heat stroke results in approximately 4,100 ED visits each year in the United States, with the majority occurring in the summer months and requiring admission to the hospital. Men, the elderly, and people living in the south region are at heightened risk.
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... It is estimated that, annually, 1300 people die every year in the U.S. from extreme heat 3 . In 2009 and 2010 alone, over 8250 emergency room visits in the US were caused by heat stroke 4 , with lowincome, minority, and elderly populations being disproportionally affected 3 . A large portion of these deaths may have been prevented if people could cool their homes properly. ...
Income-based energy poverty metrics ignore people’s behavior patterns, particularly reducing energy consumption to limit financial stress. We investigate energy-limiting behavior in low-income households using a residential electricity consumption dataset. We first determine the outdoor temperature at which households start using cooling systems, the inflection temperature. Our relative energy poverty metric, the energy equity gap, is defined as the difference in the inflection temperatures between low and high-income groups. In our study region, we estimate the energy equity gap to be between 4.7–7.5 °F (2.6–4.2 °C). Within a sample of 4577 households, we found 86 energy-poor and 214 energy-insecure households. In contrast, the income-based energy poverty metric, energy burden (10% threshold), identified 141 households as energy-insecure. Only three households overlap between our energy equity gap and the income-based measure. Thus, the energy equity gap reveals a hidden but complementary aspect of energy poverty and insecurity. In the summer, low-income households in the Arizona, US wait 4 - 7 °F (2.6–4.2 °C) longer than high-income households to turn on their AC units to save money on energy bills. This energy limiting behavior indicates a hidden form of energy poverty.
... It is estimated that, annually, 1,300 people die every year in the U.S. from extreme heat 3 . In 2009 and 2010 alone, over 8,250 emergency room visits in the US were caused by heat stroke 4 , with low-income, minority, and elderly populations being disproportionally affected 3 . A large portion of these deaths could have been prevented if people could cool their homes properly 5,6 . ...
Income-based energy poverty metrics miss people's behavior (i.e., reducing energy consumption to limit financial stress). We introduce a novel method for calculating energy-limiting behavior in low-income households using a residential electricity consumption dataset. We first determine the outdoor temperature at which households start using cooling systems, the inflection temperature. Our energy poverty metric, the energy equity gap , is defined as the difference in the inflection temperatures between low and high-income groups. In our study region, we estimate the energy equity gap to be between 4.7°F and 7.5°F. In 2015–2016, within our sample of 4,577 households, we found 86 energy-poor and 214 energy-insecure households. In contrast, the income-based energy burden metric identified 141 households as energy insecure when the threshold was set to 10%. Only three households overlapped between the energy equity gap and energy burden measures. Thus, the energy equity gap reveals a hidden but complementary aspect of energy poverty.
... Our study reported an in-hospital mortality rate of 5%, which has been previously reported ranging from 3% to 7%. 16,20,21,30,33 When considering mortality as a result of heatstroke, environmental heatwaves are an important external factor to consider. Previous data showed a concerning rise in deaths during heat wave in Europe in August 2003 and Chicago in the summer of 1995. ...
This study aimed to assess inpatient prevalence, characteristics, outcomes, and resource utilisation of hospitalisation for heatstroke in the United States. Additionally, this study aimed to explore factors associated with in‐hospital mortalities of heatstroke.
The 2003‐2014 National Inpatient Sample database was used to identify hospitalised patients with a principal diagnosis of heatstroke. The inpatient prevalence, clinical characteristics, in‐hospital treatments, outcomes, length of hospital stay, and hospitalisation cost were studied. Multivariable logistic regression was performed to identify independent factors associated with in‐hospital mortality.
A total of 3372 patients were primarily admitted for heatstroke, accounting for an overall inpatient prevalence of heatstroke amongst hospitalised patients of 36.3 cases per 1 000 000 admissions in the United States with an increasing trend during the study period (P < .001). Age 40‐59 was the most prevalent age group. During the hospital stay, 20% required mechanical ventilation, and 2% received renal replacement therapy. Rhabdomyolysis was the most common complication. Renal failure was the most common end‐organ failure, followed by neurological, respiratory, metabolic, hematologic, circulatory, and liver systems. The in‐hospital mortality rate of heatstroke hospitalisation was 5% with a decreasing trend during the study period (P < .001). The presence of end‐organ failure was associated with increased in‐hospital mortality, whereas more recent years of hospitalisation was associated with decreased in‐hospital mortality. The median length of hospital stay was 2 days. The median hospitalisation cost was $17 372.
The inpatient prevalence of heatstroke in the United States increased, while the in‐hospital mortality of heatstroke decreased.
... Specifically, EHS is more commonly associated with young adults, whereas nonexertional heat stroke (ie, classical heat stroke) more often affects infants and the elderly. 15,16 Across age ranges, thermoregulatory function in response to exercise heat stress changes. Older adults have been observed to have blunted sudomotor function and skin blood flow, which increased their heat strain compared with younger adults. ...
Sex, age, and wet-bulb globe temperature (WBGT) have been proposed risk factors for exertional heat stroke (EHS) despite conflicting laboratory and epidemiologic evidence.
To examine differences in EHS incidence while accounting for sex, age, and environmental conditions.
Main Outcome Measure(s)
Using data from the Falmouth Road Race, a warm-weather 7-mi (11.26-km) running road race, we reviewed records from patients treated for EHS at medical tents. The relative risk (RR) of EHS between sexes and across ages was assessed with males as the reference population. Multivariate linear regression analyses were calculated to determine the relative contribution of sex, age, and WBGT to the incidence of EHS.
Among 343 EHS cases, the female risk of EHS was lower overall (RR = 0.71; 95% confidence interval [CI] = 0.58, 0.89; P = .002) and for age groups 40 to 49 years (RR = 0.43; 95% CI = 0.24, 0.77; P = .005) and 50 to 59 years (RR = 0.31; 95% CI = 0.13, 0.72; P = .005). The incidence of EHS did not differ between sexes in relation to WBGT (P > .05). When sex, age, and WBGT were considered in combination, only age groups <14 years (β = 2.41, P = .008), 15 to 18 years (β = 3.83, P < .001), and 19 to 39 years (β = 2.24, P = .014) significantly accounted for the variance in the incidence of EHS (R2 = .10, P = .006).
In this unique investigation of EHS incidence in a road race, we found a 29% decreased EHS risk in females compared with males. However, when sex was considered with age and WBGT, only younger age accounted for an increased incidence of EHS. These results suggest that road race medical organizers should consider participant demographics when organizing the personnel and resources needed to treat patients with EHS. Specifically, organizers of events with greater numbers of young runners (aged 19 to 39 years) and males should prioritize ensuring that medical personnel are adequately prepared to handle patients with EHS.
... Approximately, heatstroke in the United States (U.S.) results in 4100 emergency department visits per year, with most occurring during the summer and requiring hospitalization . The mortality rate ranges between 3-7% and is expected to rise in coming years due to climate change . ...
Background: This study aimed to assess the risk factors and the association of circulatory failure with treatments, complications, outcomes, and resource utilization in hospitalized patients for heatstroke in the United States. Methods: Hospitalized patients with a principal diagnosis of heatstroke were identified in the National Inpatient Sample dataset from the years 2003 to 2014. Circulatory failure, defined as any type of shock or hypotension, was identified using hospital diagnosis codes. Clinical characteristics, in-hospital treatment, complications, outcomes, and resource utilization between patients with and without circulatory failure were compared. Results: A total of 3372 hospital admissions primarily for heatstroke were included in the study. Of these, circulatory failure occurred in 393 (12%) admissions. Circulatory failure was more commonly found in obese patients, but less common in older patients aged ≥60 years. The need for mechanical ventilation, blood transfusion, and renal replacement therapy were higher in patients with circulatory failure. Hyperkalemia, hypocalcemia, metabolic acidosis, metabolic alkalosis, sepsis, ventricular arrhythmia or cardiac arrest, renal failure, respiratory failure, liver failure, neurological failure, and hematologic failure were associated with circulatory failure. The in-hospital mortality was 7.1-times higher in patients with circulatory failure. The length of hospital stay and hospitalization costs were higher when circulatory failure occurred while in the hospital. Conclusions: Approximately one out of nine heatstroke patients developed circulatory failure during hospitalization. Circulatory failure was associated with various complications, higher mortality, and increased resource utilizations.
... An estimated 8251 emergency department visits for NEHS occurred in the United States between 2009 and 2010, a rate of 1.34 visits per 100,000 population. 13 During a two-week heat wave in 2006 in California there were 655 heat-related deaths, 1620 additional hospitalizations, and more than 16,000 additional emergency department visits, estimated to have cost $5.4 billion. 14 The United States Armed Forces reported 578 incidents of heat stroke in [ 3 8 6 _ T D $ D I F F ] 2018, 0.45 cases per 1000 person-years, with the highest incidence amongst young men, persons of Asian and pacific island ethnicity and trainees. ...
Heat stroke is an emergent condition characterized by hyperthermia (>40 °C/>104 °F) and nervous system dysregulation. There are two primary etiologies: exertional which occurs during physical activity and non-exertional which occurs during extreme heat events without physical exertion. Left untreated, both may lead to significant morbidity, are considered a special circumstance for cardiac arrest and cause of mortality.
We searched Medline, Embase, CINAHL and SPORTDiscus. We used Grading of Recommendations Assessment, Development and Evaluation (GRADE) methods and risk of bias assessments to determine the certainty and quality of evidence. We included randomized controlled trials, non-randomized trials, cohort studies and case series of five or more patients, evaluating adults and children with non-exertional or exertional heat stroke or exertional hyperthermia, and any cooling technique applicable to first aid and prehospital settings. Outcomes included: cooling rate, mortality, neurological dysfunction, adverse effects and hospital length of stay.
We included 63 studies, of which 37 were controlled studies, two were cohort studies and 24 were case series of heat stroke patients. Water immersion of adults with exertional hyperthermia [cold water (14-17°C/57.2-62.6°F), colder water (8-12°C/48.2-53.6°F) and ice water (1-5°C/33.8-41°F)] resulted in faster cooling rates when compared to passive cooling. No single water temperature range was found to be associated with a quicker core temperature reduction than another (cold, colder or ice).
Water immersion techniques (using 1-17°C water) most effectively lowered core body temperatures when compared with passive cooling, in hyperthermic adults. The available evidence suggests water immersion can rapidly reduce core body temperature in settings where it is feasible.
Heat stress disorders or heat-related illnesses are a kind of physiological damage that occurs when the body cannot dissipate enough heat due to its thermoregulatory dysfunction. This paper aims to summarize the latest information on the diagnosis and treatment of heat-related illnesses. Heat stress disorders come in a variety of forms including heat edema, heat rash, heat cramps, heat syncope, heat tetany, severe heat exhaustion, and life-threatening heatstroke. Major risk factors may include excessive exercise, continuous exposure to high temperatures or humid environments, lack of acclimation, excessive clothing or protective equipment, obesity, and dehydration. Additional risk factors may include the patientʼs existing medical condition, environmental and personal factors, and the use of various drugs. Mild heat-related illnesses can be treated only by supportive care such as moving patients to a cool place and laying them in a supine position while elevating their legs and loosening their clothes. However, in the case of heatstroke, quickly lowering the body temperature is an essential in reducing the mortality rate. The most effective cooling method is to immerse the entire body in ice cold water.
Compared with mortality, the impact of weather and climate on human morbidity is less well understood, especially in the cold season. We examined the relationships between weather and emergency department (ED) visitation at hospitals in Roanoke and Charlottesville, Virginia, two locations with similar climates and population demographic profiles. Using patient-level data obtained from electronic medical records, each patient who visited the ED was linked to that day’s weather from one of 8 weather stations in the region based on each patient’s ZIP code of residence. The resulting 2010–2017 daily ED visit time series were examined using a distributed lag non-linear model to account for the concurrent and lagged effects of weather. Total ED visits were modeled separately for each location along with subsets based on gender, race, and age.
The relationship between the relative risk of ED visitation and temperature or apparent temperature over lags of one week was positive and approximately linear at both locations. The relative risk increased about 5% on warm, humid days in both cities (lag 0 or lag 1). Cold conditions had a protective effect, with up to a 15% decline on cold days, but ED visits increased by 4% from 2–5 days after the cold event. The effect of thermal extremes tended to be larger for non-whites and the elderly, and there was some evidence of a greater lagged response for non-whites in Roanoke. Females in Roanoke were more impacted by winter cold conditions than males, who were more likely to show a lagged response at high temperatures. In Charlottesville, males sought ED attention at lower temperatures than did females.
The similarities in the ED response patterns between these two hospitals suggest that certain aspects of the response may be generalizable to other locations that have similar climates and demographic profiles.
Heat stroke occurs when the body's core temperature becomes elevated above 40 °C, which may impact multiple organ systems. We present a case of heat stroke resulting in acute liver injury (ALI) successfully treated with intravenous N-acetylcysteine (NAC).
A 24-year-old unresponsive male without significant past medical history presented to the emergency department with heat stroke; his initial temperature was 107.4 °F. During his hospital course, he developed ALI with significant elevation in aspartate aminotransferase, alanine aminotransferase, and total bilirubin. These laboratory findings peaked by hospital day two, but improved prior to discharge on hospital day five and throughout his follow up clinic visits. His treatment course included cooling measures, supportive care, supplemental oxygen and airway management, seizure control, and intravenous NAC therapy.
Hepatocellular injury is one of the most serious complications of heat stroke. We discuss the incidence and outcomes for patients who develop acute liver injury secondary to heat stroke and the use of NAC as an early potential therapeutic option.
The human body is equipped with physiological systems that aid in heat dissipation during heat stress. These systems work to limit heat storage during heat stress to maintain a relatively constant internal body temperature. Thermal stress such as passive heat stress, exercise, or exercise in the heat exacerbates thermal strain and must be managed through various thermoeffector responses. This chapter provides a fundamental understanding of the body’s physiological responses to heat stress and biophysical factors that promote or interfere with heat loss. Our aim is to first examine environmental and exercise conditions that optimize heat loss and address biophysical determinants that result in metabolic heat production and heat dissipation. We also present neurological control of heat stress and ways in which neural control of physiological systems enhance heat loss. Finally, we address heat acclimatization and behavioral thermoregulation as methods to further enhance heat loss during heat stress.
This study was conducted to investigate the relationship between heat-related illnesses developed in the summer of 2012 and temperature.
The study analyzed data generated by a heat wave surveillance system operated by the Korea Centers for Disease Control and Prevention during the summer of 2012. The daily maximum temperature, average temperature, and maximum heat index were compared to identify the most suitable index for this study. A piecewise linear model was used to identify the threshold temperature and the relative risk (RR) above the threshold temperature according to patient characteristics and region.
The total number of patients during the 3 months was 975. Of the three temperature indicators, the daily maximum temperature showed the best goodness of fit with the model. The RR of the total patient incidence was 1.691 (1.641 to 1.743) per 1℃ after 31.2℃. The RR above the threshold temperature of women (1.822, 1.716 to 1.934) was greater than that of men (1.643, 1.587 to 1.701). The threshold temperature was the lowest in the age group of 20 to 64 (30.4℃), and the RR was the highest in the ≥65 age group (1.863, 1.755 to 1.978). The threshold temperature of the provinces (30.5℃) was lower than that of the metropolitan cities (32.2℃). Metropolitan cities at higher latitudes had a greater RR than other cities at lower latitudes.
The influences of temperature on heat-related illnesses vary according to gender, age, and region. A surveillance system and public health program should reflect these factors in their implementation.
Changes in air temperature and its relation to ambulance transports due to heat stroke in all 47 prefectures, in Japan were evaluated.
Data on air temperature were obtained from the Japanese Meteorological Agency. Data on ambulance transports due to heat stroke was directly obtained from the Fire and Disaster Management Agency, Japan. We also used the number of deaths due to heat stroke from the Ministry of Health, Labour and Welfare, Japan, and population data from the Ministry of Internal Affairs and Communications. Chronological changes in parameters of air temperature were analyzed. In addition, the relation between air temperature and ambulance transports due to heat stroke in August 2010 was also evaluated by using an ecological study.
Positive and significant changes in the parameters of air temperature that is, the mean air temperature, mean of the highest air temperature, and mean of the lowest air temperature were noted in all 47 prefectures. In addition, changes in air temperature were accelerated when adjusted for observation years. Ambulance transports due to heat stroke was significantly correlated with air temperature in the ecological study. The highest air temperature was significantly linked to ambulance transports due to heat stroke, especially in elderly subjects.
Global warming was demonstrated in all 47 prefectures in Japan. In addition, the higher air temperature was closely associated with higher ambulance transports due to heat stroke in Japan.
Daily mortality is typically higher on hot days in urban areas, and certain population groups experience disproportionate risk. Air conditioning (AC) has been recommended to mitigate heat-related illness and death. We examined whether AC prevalence explained differing heat-related mortality effects by race. Poisson regression was used to model daily mortality in Chicago, Detroit, Minneapolis, and Pittsburgh. Predictors included natural splines of time (to control seasonal patterns); mean daily apparent temperature on the day of death, and averaged over lags 1–3; barometric pressure; day of week; and a linear term for airborne particles. Separate, city-specific models were fit to death counts stratified by race (Black or White) to derive the percent change in mortality at 29 ºC, relative to 15 ºC (lag 0). Next, city-specific effects were regressed on city-and race-specific AC prevalence. Combined effect estimates across all cities were calculated using inverse variance-weighted averages. Prevalence of central AC among Black households was less than half that among White households in all four cities, and deaths among Blacks were more strongly associated with hot temperatures. Central AC prevalence explained some of the differences in heat effects by race, but room-unit AC did not. Efforts to reduce disparities in heat-related mortality should consider access to AC.
To present recommendations for the prevention and screening, recognition, and treatment of the most common conditions resulting in sudden death in organized sports.
Cardiac conditions, head injuries, neck injuries, exertional heat stroke, exertional sickling, asthma, and other factors (eg, lightning, diabetes) are the most common causes of death in athletes.
These guidelines are intended to provide relevant information on preventing sudden death in sports and to give specific recommendations for certified athletic trainers and others participating in athletic health care.
The short but intense heat wave in mid-July 1995 caused 830 deaths
nationally, with 525 of these deaths in Chicago. Many of the dead were
elderly. and the event raised great concern over why it happened.
Assessment of causes for the heat wave-related deaths in Chicago
revealed many factors were at fault, including an inadequate local heat
wave warning system, power failures, questionable death assessments,
inadequate ambulance service and hospital facilities, the heat island,
an aging population, and the inability of many persons to properly
ventilate their residences due to fear of crime or a lack of resources
for fans or air conditioning. Heat-related deaths appear to be on the
increase in the United States. Heat-related deaths greatly exceed those
caused by other life-threatening weather conditions. Analysis of the
impacts and responses to this heat wave reveals a need to 1) define the
heat island conditions during heat waves for all major cities is a means
to improve forecasts of threatening conditions, 2) develop a nationally
uniform means for classifying heat-related deaths, 3) improve warning
systems that are designed around local conditions of large cities, and
4) increase research on the meteorological and climatological aspects of
heat stress and heat waves.
It is estimated that more than 9000 high school athletes are treated for exertional heat illness annually. Risk factors include being obese and beginning practice during hot and humid weather, when athletes are not yet acclimated to physical exertion in heat.
To describe the epidemiology of exertional heat illness in high school athletes.
National High School Sports-Related Injury Surveillance System data (2005/2006-2010/2011) were analyzed in 2012 to calculate rates and describe circumstances of exertional heat illness.
Exertional heat illness occurred at a rate of 1.20 per 100,000 athlete exposures (95% CI=1.12, 1.28). Exertional heat illnesses were widely distributed geographically, and most occurred in August (60.3%). Of the exertional heat illnesses reported during practice, almost one third (32.0%) occurred more than 2 hours into the practice session. The exertional heat illness rate in football (4.42 per 100,000 athlete exposures) was 11.4 times that in all other sports combined (95% CI=8.3, 15.5, p<0.001). In addition, approximately one third (33.6%) of exertional heat illnesses occurred when a medical professional was not onsite at the time of onset.
Although most exertional heat illnesses occurred in football, athletes in all sports and all geographic areas are at risk. Because exertional heat illness frequently occurs when medical professionals are not present, it is imperative that high school athletes, coaches, administrators, and parents are trained to identify and respond to it. Implementing effective preventive measures depends on increasing awareness of exertional heat illness and relevant preventive and therapeutic countermeasures.
To assess the symptoms of heat illness experienced by surface mine workers.
Ninety-one surface mine workers across three mine sites in northern Australia completed a heat stress questionnaire evaluating their symptoms for heat illness. A cohort of 56 underground mine workers also participated for comparative purposes. Participants were allocated into asymptomatic, minor or moderate heat illness categories depending on the number of symptoms they reported. Participants also reported the frequency of symptom experience, as well as their hydration status (average urine colour).
Heat illness symptoms were experienced by 87 and 79 % of surface and underground mine workers, respectively (p = 0.189), with 81–82 % of the symptoms reported being experienced by miners on more than one occasion. The majority (56 %) of surface workers were classified as experiencing minor heat illness symptoms, with a further 31 % classed as moderate; 13 % were asymptomatic. A similar distribution of heat illness classification was observed among underground miners (p = 0.420). Only 29 % of surface miners were considered well hydrated, with 61 % minimally dehydrated and 10 % significantly dehydrated, proportions that were similar among underground miners (p = 0.186). Heat illness category was significantly related to hydration status (p = 0.039) among surface mine workers, but only a trend was observed when data from surface and underground miners was pooled (p = 0.073). Compared to asymptomatic surface mine workers, the relative risk of experiencing minor and moderate symptoms of heat illness was 1.5 and 1.6, respectively, when minimally dehydrated.
These findings show that surface mine workers routinely experience symptoms of heat illness and highlight that control measures are required to prevent symptoms progressing to medical cases of heat exhaustion or heat stroke.
When athletes, warfighters, and laborers perform intense exercise in the heat, the risk of exertional heat stroke (EHS) is ever present. The recent data regarding the fatalities due to EHS within the confines of organized American sport are not promising: during the past 35 years, the highest number of deaths in a 5-year period occurred from 2005 to 2009. This reminds us that, regardless of the advancements of knowledge in the area of EHS prevention, recognition, and treatment, knowledge has not been translated into practice. This article addresses important issues related to EHS cause and care. We focus on the predisposing factors, errors in care, physiology of cold water immersion, and return-to-play or duty considerations.