Conducted by Hyunjee Kim, Ph.D., from Oregon Health & Science University, the retrospective time-series study analyzed national data from 2016 to 2019, encompassing over 5.4 million individuals across 28,404 zip code areas in the U.S. and Washington, D.C.

In this study, heat waves were defined as three or more consecutive days with temperatures reaching at least 90°F, exceeding the 97th percentile for daily maximum temperatures in each area.

The findings revealed that during heat wave days, the incidence rates of heat-related emergency department visits and hospitalizations were significantly higher, with incidence rate ratios of 1.10 and 1.07, respectively, compared to non-heat wave days.

Moreover, mortality rates were found to be 4% higher on heat wave days, indicating a serious health impact.

The study also noted an increased incidence of death during heat wave days, with an incidence rate ratio of 1.04.

All racial and ethnic groups experienced increased emergency department visits during heat waves, with the highest incidence observed among Asian beneficiaries, who had an incidence rate ratio of 1.21.

Subgroup analysis indicated that the association between heat waves and emergency department visits was particularly significant in individuals located in the Northwest, Ohio Valley, and West climate regions.

These regions showed particularly high rates of heat-related health issues, underscoring the geographic disparities in health impacts.

In light of these findings, clinicians are encouraged to conduct routine heat wave risk assessments and adjust treatments for vulnerable patients during extreme heat events, as emphasized by Jose F. Figueroa, MD, MPH.

The authors stress the heightened vulnerability of dually eligible seniors during heat waves and advocate for tailored adaptation strategies to address the anticipated increase in the frequency and intensity of such events.

However, the study faced limitations, including reliance on claims data that may overlook heat-related conditions, a lack of adjustment for air quality, and the inability to compare outcomes with non-dually eligible individuals.

A recent study published in JAMA Health Forum on November 8, 2024, highlights the significant health risks posed by heat waves, particularly for adults aged 65 and older who are dually eligible for Medicare and Medicaid.