by Elana Gotkine

Heat-related mortality rates increased from 1999 to 2023 in the United States, according to a research letter published online Aug. 26 in the Journal of the American Medical Association.

Jeffrey T. Howard, Ph.D., from the University of Texas at San Antonio, and colleagues examined trends in heat-related mortality rates in the U.S. population from 1999 to 2023. For each year, the age-adjusted mortality rates (AAMRs) per 100,000 person-years were extracted for heat-related deaths.

The researchers found 21,518 deaths were recorded as heat-related underlying or contributing cause of death, with an AAMR of 0.26 per 100,000 person-years. From 1999 to 2023, there was an increase in the number of heat-related deaths from 1,069 to 2,325 (AAMRs, 0.38 to 0.62, respectively). The lowest number of heat-related deaths was 311 in 2004, and the highest was 2,325 in 2023. During the entire period, the AAMR increased by 3.6% per year.

Year-to-year variability was seen in the number of heat-related deaths and AAMR, with spikes in 2006 and 2011, and steady increases after 2016. A nonsignificant decrease of 1.4% per year was seen from 1999 to 2016, followed by a significant 16.8% increase per year from 2016 to 2023.

"Although a study using data through 2018 found a downward trend in heat-related mortality in the U.S., this study is the first to our knowledge to demonstrate a reversal of this trend from 2016 to 2023," the authors write.

More information: Howard, J. T. et al. Trends of Heat-Related Deaths in the US, 1999-2023, JAMA (2024). DOI: 10.1001/jama.2024.16386 jamanetwork.com/journals/jama/fullarticle/2822854

Journal information: Journal of the American Medical Association 

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