New Heat-Wave Hospitalization Risks Identified

May 12, 2015

Study Finds Previously Unaccounted Specific Risks for Hospital Admission During Heat-Waves.

Epidemiological evidence of non-communicable health impacts from extreme heat and heat-waves has been gaining as more epidemiological evidence continues to find positive associations with cardiovascular and respiratory mortality and hospital admissions. In a recent study from Dr. Jennifer F. Bobb et al. at the Harvard School of Public Health was able to go beyond cardiovascular and respiratory disease hospitalizations to identify previously unaccounted for cause-specific risks for hospitalizations in the Medicare population during extreme heat events from 1999 - 2010.

Working with Medicare data allowed the researchers to identify the specific cause of admission every day in the elderly population which is at an increased risk to adverse health impacts from extreme heat. Using clinical classification software the researchers were able to group daily hospital admissions at the county level into cause-specific disease groups on heat-wave days; which were defined as at least two consecutive days where the average daily temperature exceeds the 99th percentile within each individual county. Daily cause-specific hospital admission rates were calculated at the county level for heat-wave days and were subtracted from the admission rates of non-heatwave days matched to the same week and county. 

Researchers found significant increases in the risk of being admitted to the hospital for electrolyte disorder, renal failure, urinary tract infections, heat stroke and septicemia (a severe bacterial blood infection) during heat-waves compared to non-heatwave days. Previous research on health-impacts of extreme heat and heat-waves have predominantly focused on pre-specified cardiovascular and respiratory diseases, missing other potential adverse health impacts. This research provides evidence for a previously unaccounted relationship between extreme-heat exposure and other disease outcomes such as renal failure which have also been observed in occupational heat-stress research. These findings can benefit clinicians, emergency care workers and hospitals by providing information for heat-wave preparedness plans to anticipate potential increases in cause-specific adverse health impacts. Additionally, this research has benefits for climate change impact modelers to consider a wide-variety of adverse health impacts in projections for human impacts.

Citation: Bobb JF, Obermeyer Z, Wang Y, Dominici F. .Bell ML. Cause-specific risk of hospital admission related to extreme heat in older adults. Journal of the American Medical Association. 2014: 312(24):2659-2667. doi: 10.100/jama.2014.15715 

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