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Individuals with intellectual and developmental disabilities (IDDs) often experience fragile health care utilization patterns and are vulnerable in health care systems, particularly for emergency department visits and psychiatric services, due to communication barriers, psychiatric comorbidities, and dependence on caregivers. Emerging evidence has shown that high ambient temperatures increase emergency department (ED) utilization and mortality risk, and these risks are expected to intensify as climate change increases the frequency and severity of extreme heat. Despite growing climate-health research, the impact of heat exposure on ED utilization among individuals with IDD remains largely unexamined. This study addresses this gap by evaluating how heat stress is associated with ED utilization among individuals with IDDs in New York State.
Methods: We linked the New York State Emergency Department Database (SEDD) with Parameter-elevation Regressions on Independent Slopes Model (PRISM) weather data. Heat exposure was measured using wet-bulb globe temperature (WBGT), which captures both temperature and humidity. Individuals living with IDDs and ED visit reasons were identified using ICD-10 diagnosis codes. We aggregated 291,114 IDD-related ED visits (2016–2023) in New York State to the county-month level and estimated Poisson fixed-effects models using the number of days per month within predefined WBGT ranges, with 18–22°C as the reference range. Exploratory analyses examined differences across age groups, ED visit categories, and IDD subgroups.
Results: Consistent with prior panel studies, the 26–30°C bin emerged as the most policy-relevant heat exposure window. Using 18–22°C as the reference temperature range, monthly ED visits increased with one additional day in the 26–30°C range across several clinically meaningful outcomes and groups. Monthly ED visit increased by approximately 1.0% for symptom-related ED visits (p<.05), 1.0% for psychiatric service visits (p<.01), and 1.0% for heat-sensitive conditions (p<.01). Among IDD subgroups, autism spectrum disorder (ASD) showed a slightly stronger response, with monthly ED visit increasing by approximately 1.2% in response to an additional 26–30°C Day (p<.001). A similar positive pattern was also observed among adults aged 22–65 with 1.2% increase (p<.01). At temperatures greater than 30°C, however, this relationship reversed. Monthly ED visits declined for psychiatric services and heat-sensitive conditions, suggesting a potential service-suppressing effect under extreme heat exposure, consistent with prior literature. This pattern indicates that while moderately hot temperatures elevate acute service needs, more severe heat may reduce realized ED utilization.
Conclusions and Implications: Findings suggest that the effects of environmental heat stress on individuals with IDDs require greater attention from health care providers, Long-term services and supports (LTSS) provider, social service systems, caregivers, and practitioners. Both medical and supportive services should explicitly account for the impact of high heat in the design of follow-up care, crisis planning, and community-based supports to promote health equity among people with IDDs. The observed service-suppressing effect under extreme heat further suggests that reduced outdoor activity, mobility limitations, and disrupted care-seeking behaviors during severe heat should be proactively considered by care providers and caregivers when planning service delivery and outreach.