DefinitionA heat stress hospitalization is an admission of a New Mexico resident to an acute care in-state hospital that occurs in state as an inpatient between May 1 to September 30, inclusive, during each year.
Heat stress is defined as a constellation of explicit effects of hot weather on the body, including heat stroke, and sunstroke (hyperthermia), heat syncope or collapse, heat exhaustion, heat cramps, heat fatigue, heat edema, and other unspecified clinical effects attributed to excessive heat exposure.
Cases of heat stress are classified as any primary or other diagnosis included in the rage of the International Classification of Diseases, 9th edition, Clinical Modification (ICD_9-CM) 992.0-992.9 or cause of injury code in the range E900.0 or E900.9 or ICD-10-CMs T67, X30, or X32 (excluding cases with a code W92). However, cases with a code of E900.1 (man-made source of heat) anywhere in the patient medical record are excluded.
Measures include 1) the number of ED visits for heat stress; 2) crude rate of ED visits for heat stress per 100,000 population; and 3) age-adjusted rate of ED visits for heat stress per 100,000 population (adjusted by the direct method to the 2000 US standard population).
NumeratorNumber of inpatients treated between May 1 and September 30, inclusive, for each year, where heat stress is any primary or other diagnosis.
DenominatorMidyear New Mexico resident population.
Data Interpretation IssuesThis indicator estimates the number and rate of inpatients for heat stress among New Mexico residents. It includes all cases where heat stress is listed as a primary or other diagnosis. These data are derived from hospital records and may not capture the full range of health-related illness if exposure to extreme heal is not explicitly documented. Due to incomplete e-coding, there may be an underestimation of hospitalizations for heat stress. Further, data were submitted by individual hospitals.
Why Is This Important?Over the last 50 years (1960-2010+), maximum daily temperatures in New Mexico increased (data not shown). State land weather station data analysis using time series models reveal that high temperatures increased 0.08 degrees Fahrenheit each year during this period, for a total increase of 4 degrees Fahrenheit.
This trend of increasing temperature is likely to continue, based on projections of the future climate of New Mexico derived from global and regional climate models data with the assumption that global anthropogenic emissions of greenhouse gases will continue to increase. Specifically, these climate models project the following substantial changes in New Mexico climate over the next fifty to one hundred years: a) average air temperature will become substantially warmer by 6-12 degrees Fahrenheit (3.3-6.7 degrees Celsius) and b) there will be more episodes of extreme heat, heat waves and fewer episodes of extreme cold.
As temperatures increase, the public health concern is heat-related illness. Any individual, regardless of age, sex, or health status may develop heat-related illness if engaged in intense physical activity and/or exposed to environmental heat, even in the dry environmental conditions of New Mexico. Physiologic mechanisms maintain core body temperature in the narrow optimum range around 37 degrees Celsius(98.6 degrees Fahrenheit). The normal physiologic response to rising core body temperature is to sweat and circulate blood closer to the skin surface to increase the cooling. When heat exposure exceeds the physiologic capacity to cool and the core body temperature continues to rise, a range of heat-related adverse health effects can result. Although some of these signs and symptoms, such as heat-related cramps, syncope, and edema are relatively minor and readily treatable, they should be used as warning signs to immediately remove the affected individual from the exposure. Other conditions such as heat exhaustion may progress to heat stroke, the most serious form of heat-related disease, which if untreated can result in death or permanent neurological impairment.
The New Mexico Environmental Public Health Tracking Network (NMEPHTN) develops, monitors and analyzes indicators of heat stress to help document changes in morbidity and mortality over place and time due to heat, monitor vulnerable areas and New Mexico communities, and to inform and evaluate the results of local climate-adaptation strategies and perhaps, extreme heat warning systems, once those become implemented. One of the heat stress morbidity indicators that is tracked are hospitalizations for heat stress.
Other ObjectivesCDC Environmental Public Health Tracking, Nationally Consistent Data and Measures (EPHT NCDM)