Association between summertime emergency department visits and maximum daily heat index in rural and non-rural areas of Virginia (2015–2022)

Abstract

There is growing evidence that high ambient temperatures are associated with a range of adverse health outcomes. Further evidence suggests differences in rural versus non-rural populations' vulnerability to heat-related adverse health outcomes. The current project aims to 1) refine estimated associations between maximum daily heat index (HI) and emergency department (ED) visits in regions of Virginia, and 2) compare associations between maximum daily HI and ED visits in rural versus non-rural areas of Virginia and within those areas, for persons 65 years of age and older versus those younger than 65 years. Our study utilized 16,873,213 healthcare visits from Virginia facilities reporting to the Virginia Department of Health syndromic surveillance system between May and September 2015–2022. Federal Office of Rural Health Policy defined rural areas were assigned to patient home ZIP code. The estimated daily maximum HI at which ED visits begin to rise varies between 25 °C and 33 °C across climate zones and regions of Virginia. Across all regions, estimated ED visits attributable to days with maximum HI above 25.7 °C were higher in rural areas (3.7 %, 95 % CI: 3.5 %, 3.9 %) versus in non-rural areas (3.1 %, 95 % CIs: 3.0 %, 3.2 %). Patients aged 0–64 years had a higher estimated heat attributable fraction of ED visits (4.2 %, 95 % CI: 4.0 %, 4.3 %) than patients 65 years and older (3.1 %, 95 % CI: 2.9 %, 3.4 %). Rural patients older than 65 have a higher estimated fraction of heat attributable ED visits (2.7 %, 95 % CI: 2.2 %, 3.1 %) compared to non-rural patients 65 years and older (1.5 %, 95 % CI: 1.3 %, 1.8 %). State-level syndromic surveillance data can be used to optimize heat warning messaging based on expected changes in healthcare visits given a set of meteorological variables, and can be further refined based on climate, rurality and age.