Extreme Heat Linked to 33 Clinically Reportable Diagnoses

WEDNESDAY, Aug. 26, 2026 (HealthDay News) — Extreme heat is associated with 33 diagnoses, including multiple sclerosis, injuries, and dermatologic and pressure-related conditions, according to a study published online Aug. 26 in Science Advances.

Hyojung Jang, from the Northwestern University Feinberg School of Medicine in Chicago, and colleagues conducted a heat-wide association study to assess acute-care diagnoses associated with extreme heat in Chicago. Data were included for 916,904 acute care visits, including emergency department and urgent care encounters, among 372,140 adults across four health care systems from 2011 to 2023. Diagnosis codes associated with heat were screened using quasi-Poisson regression, followed by characterization of exposure-response and lag patterns in a time-stratified case-crossover design.

A total of 44 diagnosis codes were retained in stage 1; after stage 2, 33 clinically reportable diagnoses were retained. The researchers found that for multiple diagnoses, including fluid-balance and renal disorders, dermatologic and pressure-related conditions, multiple sclerosis, a cannabinoid-related mental and behavioral disorder, varicose veins of the lower extremities, and multiple injuries and external causes, cumulative odds were elevated over lags 0 to 3.

“It is a public health obligation to protect the individuals and communities most vulnerable to the harmful effects of climate change,” Jang said in a statement. “If we”re only tracking the more commonly known heat-related illnesses, we’ll underestimate the true heat-related health burden, which could result in vulnerable people and communities being overlooked.”

Abstract/Full Text