TOPLINE:

A case-control study found that extreme heat was linked to higher ED use among adults aged 65 years or older at a safety net hospital serving low-income, racially and ethnically minoritized populations, whereas no association was seen at a privately insured ED serving predominantly White patients, highlighting socioeconomic disparities in heat-related care.

METHODOLOGY:

• A case-control study of 55,200 ED encounters included 34,651 patients aged 65 years or older who were treated at two urban EDs from 2022 to 2024.
• ED-1 (n = 15,092; mean age, 74.9 years; 56.95% women; 47.8% White individuals) primarily served Medicaid-enrolled patients from racially and ethnically minoritized groups, whereas ED-2 (n = 19,559; mean age, 74.9 years; 55% women; 61.9% White individuals) served predominantly White, privately insured patients.
• Researchers assessed the association between extreme heat exposure and daily all-cause ED visit counts. Data on patients' sex, age, self-reported race and ethnicity, and insurance type were obtained from electronic health records.
• Other outcomes included daily maximum heat index (HImax) values and heat index (HI) anomalies calculated from monitor-derived recordings from the National Centers for Environmental Information between 1992 and 2021.

TAKEAWAY:

• At ED-1, the odds of ED use increased significantly after 66 °F (odds ratio [OR], 1.10; 95% CI, 1.01-1.21) and peaked at 101 °F (OR, 1.24; 95% CI, 1.11-1.39). At ED-2, no significant association was seen between heat and ED use.
• At ED-1, the odds of ED use increased with daily warm HImax anomalies, reaching statistical significance on days with HImax anomalies of 15-18 °F above average and peaking at 21 °F above average (OR, 1.13; 95% CI, 0.99-1.30). At ED-2, negative associations were observed on days with HImax anomalies of 16-21 °F above average.
• Patterns identified in the sensitivity and stratified analyses were consistent with the main findings.

IN PRACTICE:

"These findings suggest that significant heat-health risks were observed in an ED serving socioeconomically vulnerable populations, suggesting tailored heat warning strategies should be studied further," the authors wrote.

SOURCE:

The study was led by Evan Siau, MD, New York University Grossman School of Medicine, New York City. It was published online on March 20, 2026, in JAMA Network Open.

LIMITATIONS:

The study was limited by reliance on HI values from a single monitor, which may have led to exposure misclassification and ecologic fallacy. Other heat metrics such as wet bulb globe temperature were not assessed, limiting comparison with local heat advisories. Inclusion of all ED visits without excluding repeat encounters may have introduced selection bias. Additionally, the study's focus on a single urban healthcare system limited the generalizability of the findings.

DISCLOSURES:

Funding information for the study was not provided. One author reported receiving consulting fees from Ambu Consulting, the Association of Medical Device Reprocessors, and Philips outside the submitted work.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.