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Your Environment. Your Health.

Causes of Hospitalization During Heat Waves

Jennifer F. Bobb, PhD; Yun Wang, PhD; Francesca Dominici, PhD
Harvard School of Public Health
NIEHS Grants: P30ES000002, R01ES019560, R21ES020152, R21ES022585, R21ES021427

Researchers partially funded by NIEHS report that, among older adults, heat waves were associated with increased risk of hospitalization for fluid and electrolyte disorders, renal failure, urinary tract infection, sepsis, and heat stroke. Extreme heat is the most common cause of deaths tied to severe weather in the United States.

Most studies of heat-related health effects have looked at only a few predetermined health outcomes. For this study, the researchers considered all possible heat-related causes of hospitalizations from 1999 to 2010, by analyzing data in 214 disease groups from 23.7 Medicare enrollees per year (85 percent of Medicare enrollees), residing in 1,943 counties in the U.S.

The researchers found that older Americans were 2 1/2 times more likely to be hospitalized from heat stroke during heat wave periods than on non-heat wave days. Extreme heat also put the elderly at 18 percent greater risk of being hospitalized for fluid and electrolyte disorders; 14 percent greater risk for renal failure; 10 percent greater risk for urinary tract infections; and 6 percent greater risk for sepsis. The researchers said that sepsis had not been previously considered a possible outcome of extreme heat.

Longer and more extreme heat waves brought larger risks. Since risks remained elevated one to five days after a heat wave, prevention and treatment is critical not just during a heat wave, but also afterwards.

Citation: Bobb JF, Obermeyer Z, Wang Y, Dominici F. 2014. Cause-specific risk of hospital admission related to extreme heat in older adults. JAMA 312(24):2659-2667.