Extreme heat is tied to a high risk of same-day hospital admission and same-day death in people with end-stage renal disease, according to University of Maryland researchers.

Mortality data was analyzed in more than 7,400 patients who underwent long-term hemodialysis in large American cities from 2001 to 2012. Using historical weather information, the researchers determined that the death risk for these patients rose when temperatures were unusually high. 

Risk was greater among those living with additional illnesses, specifically congestive heart failure, chronic obstructive pulmonary disease and diabetes, reported Amir Sapkota, Ph.D. Risk also varied between cities and by race and/or ethnicity. 

The researchers were not able to verify indoor conditions for the patients or account for multiple-day heat waves, which could present a more severe threat for patients with ESRD, Sapkota wrote.

The study was published in JAMA Network Open.