Hyperthermia

Each year many Missourians suffer from heat-related illnesses, with some cases resulting in death.  During prolonged periods of high temperatures, using air conditioning – either at home or by seeking shelter in a local cooling center -- is the best preventive measure.

The Missouri Department of Health and Senior Services monitors high temperatures and humidity across the state to prevent heat-related illness and death. The elderly and the chronically ill are more vulnerable to the effects of high temperatures. They perspire less and are more likely to have health problems requiring medications that can impair the body's response to heat. Many prescription medications make individuals more sensitive to the heat. Some of these medications include heart drugs, some anti-Parkinsonian agents, antihistamines, over-the-counter sleeping pills, antidepressants, anti-psychotics and major tranquilizers.

The former Missouri Division of Health initiated statewide hyperthermia death surveillance in 1980 in response to a summer heat wave that resulted in the death of 295 individuals due to Missouri’s extreme weather temperatures. Hyperthermia Mortality, Missouri 1980-2008 This surveillance program defines hyperthermia as physician-diagnosed heat exhaustion, heat stroke or hot weather/natural environment as a contributing factor in a death.

In Missouri, the greatest numbers of heat-related deaths have occurred in the urban, more densely populated areas of St. Louis City, St Louis County and Jackson County (Kansas City). Of the 203 heat-related deaths reported from 2000 through 2008, there were 125 (62%) deaths in these metropolitan areas. Rural deaths accounted for 78 (38%) of the deaths. Non-Missouri residents who succumb to heat while visiting are considered cases, accounting for 5 (2%) deaths. Hyperthermia Mortality by Geographic Area, Missouri 2000-2008 White males are the most frequent victims of heat-related illness resulting in death. In the same eight-year period, there were 99 (49%) white male deaths. Hyperthermia Mortality by Race and Sex, Missouri 2000-2008 

Slightly more than half 109 (54%) of the 203 deaths during 2000-2008 were in the 65 year and older age group. Victims in this population often live alone and have other complicating medical conditions. Also, lack of air conditioning or refusal to use it for fear of higher utility expenses contributes to the number of deaths in the senior population. There were 84 (41%) hyperthermia deaths occurring in the 5 through 64-year-old age group. These deaths often have contributing causes such as physical activity (sports or work), complicating medical conditions, or substance abuse. Circumstances causing hyperthermia deaths in young children often involve a motor vehicle—a child left in or climbing into a parked vehicle during hot weather. From 2000-2008, there were 10 (5%) deaths of children less than five years of age. Hyperthermia Mortality by Age, Missouri 2000-2008 and Hyperthermia Mortality by Contributing Factor & Geographic Location of Death, Missouri 2008 and Hyperthermia Mortality by Contributing Factor, Missouri 2008

In August 2007, Missouri experienced a heat wave that lasted approximately 21 days and resulted in 34 hyperthermia deaths.  The heat wave started August 2 with a heat index of 101 in Cape Girardeau and spread across the state.  By August 7, the five cities that DHSS receives daily heat data on from the National Weather Service were experiencing heat indices of 103 or higher.  The heat index remained in the upper 90’s or higher in at least one of the five areas until August 25. 

Public and private emergency response plans were implemented across the state. These responses included opening cooling centers, distributing ice, water, and people checking door-to-door for persons in danger from the heat. Without this quick and intensive response, public health officials believe mortality from the August 2007 heat wave would have been much greater. Fortunately, hot weather during the summer of 2008 was much more sporadic and less prolonged, resulting in 10 deaths statewide.

Missouri’s highest temperatures generally occur in July and August each summer. Thus, the majority of hot-weather-related deaths also occur during these months. Of the 203 deaths from 2000-2008, 94 (46.3%) deaths were during the month of July and 78 (38.4%) were in August.

Missouri is the only state that conducts on-going statewide surveillance for hot weather-related illnesses and deaths. Health care providers are required to report cases of hyperthermia to the Missouri Department of Health and Senior Services.