摘要:Objectives. We measured the burden of hypothermia- and hyperthermia-related health care visits, identified risk factors, and determined the health care costs associated with environmental heat or cold exposure among Medicare beneficiaries. Methods. We obtained Medicare fee-for-service claims data of inpatient and outpatient health care visits for hypothermia and hyperthermia from 2004 to 2005. We examined the distribution and differences of visits by age, sex, race, geographic regions, and direct costs. We estimated rate ratios to determine risk factors. Results. Hyperthermia-related visits (n = 10 007) were more frequent than hypothermia-related visits (n = 8761) for both years. However, hypothermia-related visits resulted in more deaths (359 vs 42), higher mortality rates (0.50 per 100 000 vs 0.06 per 100 000), higher inpatient rates (5.29 per 100 000 vs 1.76 per 100 000), longer hospital stays (median days = 4 vs 2), and higher total health care costs ($98 million vs $36 million). Conclusions. This study highlighted the magnitude of these preventable conditions among older adults and disabled persons and the burden on the Medicare system. These results can help target public education and preparedness activities for extreme weather events. Older adults (≥ 65 years) and persons with chronic diseases are at risk for heat- and cold-related mortality and morbidity during extreme ambient temperatures. 1–3 Even slight changes in temperature can adversely affect these populations because of their weakened physiological adaptability and socioeconomic factors. 1,4 As the growing evidence of global climate change supports anticipated increases in the intensity and frequency of heat waves and extreme cold events, older adults and those with chronic diseases will be at an increased risk for hyperthermia and hypothermia. 1,5 The US Census Bureau projects that the number of older adults will rapidly increase during the 2010 to 2030 period. Accordingly, it is projected that by 2030, the older population will be 2 times greater than in 2000, growing from 35 million to 72 million, or nearly 20% of the total US population. 6 Little has been published on national incidence rates, risk factors, and associated health care costs of heat- and cold-related mortality and morbidity among older adults. The purpose of this study was therefore to measure the burden of hypothermia- and hyperthermia-related health care visits, identify risk factors, and estimate the direct health care costs associated with environmental exposure to heat or cold among Medicare beneficiaries. Medicare is the nation’s largest health insurance program and covers nearly 40 million Americans aged 65 years and older and persons with eligible disabilities (e.g., persons with a debilitating physical or mental disease or end-stage renal disease). 7 Findings from this study can guide preparedness planning to better target public health messaging to older Americans, disabled persons, their caregivers, and health care professionals to reduce the health effects of hot and cold weather events. In addition, we anticipate that organizations such as the Healthy Aging Research Network and the Healthy Aging Program at the Centers for Disease Control and Prevention (CDC) can use these findings to support their efforts to promote and protect the health of older adults during extreme weather events.