Abstract
IMPORTANCE: Extreme heat poses substantial health risks to older adults. Medicaid home visits in the weeks preceding such events may alleviate these risks. OBJECTIVE: To assess whether receiving regular Medicaid home visits prior to extreme heat events is associated with reduced emergency department (ED) visits during extreme heat. DESIGN, SETTING, AND PARTICIPANTS: This cohort study used claims and weather data. The changes in daily ED visits during and up to 2 days after extreme heat events were compared between dual-eligible enrollees who received weekly home visits in the preceding month (treatment group) and those who did not (comparison group). Participants included dual-eligible enrollees aged 65 years or older who received at least 1 Medicaid home visit in 2018 or 2019 in zip code tabulation areas (ZCTAs) across the US that experienced at least 1 extreme heat event between May and October in 2018 and 2019. Data were analyzed from June 2024 to October 2025. EXPOSURE: An extreme heat day was defined at the ZCTA level as a day when the maximum temperature exceeded 90 °F and was at least the 97th percentile for the same day of the year from 2006 to 2017. Consecutive extreme heat days were grouped into extreme heat events when they lasted 1 to 5 days. MAIN OUTCOME AND MEASURES: Daily ED visits per 1000 enrollees. RESULTS: Our sample included 597 388 dual-eligible enrollees (mean [SD] age, 77.2 [8.2] years; 423 474 female [70.9%]). During extreme heat, daily ED visits per 1000 enrollees increased by 1.29 (95% CI, 1.22 to 1.37) for those who received regular home visits in the preceding month and by 1.25 (95% CI, 1.19 to 1.31) for those who did not, a nonsignificant difference of 0.05 (95% CI, -0.04 to 0.14) between the 2 groups. Similar patterns in stratified analyses were found by climate region and among those with heat-sensitive chronic conditions. CONCLUSIONS AND RELEVANCE: In this cohort study of community-dwelling dual-eligible enrollees, regular Medicaid home visits prior to heat events were not associated with changes in ED visits during extreme heat. This finding suggests that while regular home visits may not have reduced ED visits during heat events, they could have helped facilitate timely care-seeking when heat-related symptoms arose.