Extreme Heat Linked to Renal Failure, Septicemia in Elderly
A new study finds that exposure to extreme heat may put older adults at increased risk of being hospitalized for a number of serious illnesses, including renal failure, septicemia, and urinary tract infections.
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A team led by researchers at Harvard School of Public Health—who note in their study that extreme heat is the most common cause of weather-related deaths in the United States—used Medicare inpatient claims data to analyze 23.7 million individuals aged 65 or older from 1,943 U.S. counties. All patients had been admitted to the hospital between 1999 and 2010, and 214 diseases were identified that accounted for these hospitalizations. In an effort to determine how periods of extreme heat may be associated with hospitalizations resulting from serious illness among elderly patients, the investigators also gathered information from more than 4,000 temperature monitors from at least five summers in the U.S
The authors identified 5 diseases associated with greater risk of hospitalization among older adults during heat waves, defining a period of extreme heat as 2 or more consecutive days exceeding the 99th percentile of daily temperatures in each county. The team found that heat stroke was the most common cause of hospitalization during these timeframes, with older adults being 2.5 times more likely to be admitted to a hospital for heat stroke during a time of extreme heat than a period with more normal temperatures.
In addition, older individuals were 18% more likely to be hospitalized for fluid and electrolyte disorders during heat waves, and at 14% greater risk of renal failure, 10% more risk of urinary tract infections, and at 6% higher risk of septicemia. The risk of hospitalization stemming from the 5 illnesses the authors identified was higher when periods of extreme heat lasted longer and were more intense, but remained statistically significant in the 1-5 days following heat wave days.
While noting that the findings would generally be “unsurprising to most clinicians,” these results “do raise the possibility that extreme heat increases the likelihood for infections progressing to sepsis, perhaps because of volume depletion,” said Ziad Obermeyer, MD, M.Phil, an assistant professor at Harvard Medical School, a practicing emergency physician at Brigham & Women’s Hospital, and co-author of the study.
Exposure to extreme heat “may also decrease the risk of acute decompensated heart failure, for the same reason,” said Obermeyer. Generally speaking, he said, “the strength of the study was to consider all possible consequences of extreme heat, rather than just the ones hypothesized from heat a priori, hence the interesting findings on sepsis as [congestive heart failure].”
—Mark McGraw
Reference:
Bobb J, Obermeyer Z, et al. Cause-specific risk of hospital admission related to extreme heat in older adults. JAMA. 2014;312(24):2659-2667.