{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,2]],"date-time":"2026-09-02T17:46:29Z","timestamp":1788371189952,"version":"build-2803163510"},"reference-count":30,"publisher":"American Medical Association (AMA)","issue":"3","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["JAMA Netw Open"],"abstract":"\n Importance<\/jats:title>\n Health care systems can help protect patients from the increasing threat of extreme heat-driven morbidity and mortality. Electronic health records (EHRs) provide insight into trends and local variation in thresholds above which extreme heat is associated with emergency department (ED) use among at-risk patient populations.<\/jats:p>\n <\/jats:sec>\n \n Objective<\/jats:title>\n To examine associations between extreme heat exposure and all-cause ED visits among patients aged 65 years and older.<\/jats:p>\n <\/jats:sec>\n \n Design, Setting, and Participants<\/jats:title>\n This matched case-control study of patients seeking emergency care at an urban health care system during the summer (May 1 to September 30) from 2022 to 2024. Two New York City (NYC) EDs were included: (1) ED-1, predominantly serving Medicaid-enrolled patients from minoritized racial and ethnic groups, and (2) ED-2, predominantly serving White, privately insured patients. Included patients were aged 65 years or older and presented to ED-1 and ED-2 during the study period. Data were analyzed from April to August 2025.<\/jats:p>\n <\/jats:sec>\n \n Exposures<\/jats:title>\n \n Daily maximum heat index (HI\n max<\/jats:sub>\n ) values during the summer were calculated from the National Centers for Environmental Information monitor-derived recordings.\n <\/jats:p>\n <\/jats:sec>\n \n Main Outcomes and Measures<\/jats:title>\n \n Daily all-cause ED use counts were derived from EHRs, and extreme heat exposure\u2013outcome curves were calculated. Daily HI\n max<\/jats:sub>\n anomalies were calculated based on a 30-year baseline average. The cumulative odds ratio (OR) and 95% CIs were calculated.\n <\/jats:p>\n <\/jats:sec>\n \n Results<\/jats:title>\n \n This study included 55\u202f200 ED encounters and represented 15\u202f092 unique patients at ED-1 and 19\u202f559 at ED-2 with a mean (SD) age of 74.9 (8.92) years at ED-1 and 74.9 (8.72) years at ED-2. Compared with ED-2, more ED-1 patients were female (8589 [56.9%] vs 10\u202f767 [55.0%]), Hispanic (3544 [23.5%] vs 2576 [13.2%]), and Medicaid-enrolled (1321 [8.8%] vs 824 [4.2%]). At ED-1, daily HI\n max<\/jats:sub>\n associations increased after 66 \u00b0F (OR, 1.10 [95% CI, 1.01-1.21]), peaking at 101 \u00b0F (OR, 1.24 [95% CI, 1.11-1.39]), and were higher on days with HI\n max<\/jats:sub>\n anomalies between 15 \u00b0F (OR, 1.07 [95% CI, 1.01-1.13]) and 18 \u00b0F (OR, 1.10 [95% CI, 1.01-1.20]) warmer than average. At ED-2, daily HI\n max<\/jats:sub>\n ED use associations were not significant and were significantly negative for days with HI\n max<\/jats:sub>\n anomalies above 16 \u00b0F, nadiring at 21 \u00b0F (0.84, 95% CI [0.73, 0.95]) warmer than average.\n <\/jats:p>\n <\/jats:sec>\n \n Conclusions and Relevance<\/jats:title>\n \n In this case-control study of the association between heat exposure and ED use in adults aged 65 years and older, positive associations were only observed at ED-1, which served a predominantly lower-income population from minoritized racial and ethnic groups. These association thresholds were not fully captured by NYC heat advisories, which were triggered by 2 days above HI\n max<\/jats:sub>\n 95 \u00b0F or any time above 100 \u00b0F, highlighting an opportunity for future research to develop targeted, risk-informed health care system-based heat warning strategies.\n <\/jats:p>\n <\/jats:sec>","DOI":"10.1001\/jamanetworkopen.2026.2645","type":"journal-article","created":{"date-parts":[[2026,3,20]],"date-time":"2026-03-20T15:30:26Z","timestamp":1774020626000},"page":"e262645","source":"Crossref","is-referenced-by-count":2,"title":["Extreme Urban Heat and Emergency Department Visits in Older Adults"],"prefix":"10.1001","volume":"9","author":[{"given":"Evan","family":"Siau","sequence":"first","affiliation":[{"name":"Department of Medicine, New York University Grossman School of Medicine, New York"},{"name":"Department of Population Health, New York University Grossman School of Medicine, New 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