Abstract Body (Do not enter title and authors here):
Background: Stroke presents a significant burden to the health care system of the United States. Previous research has shown a higher rate of stroke mortality in rural compared to urban areas. Rural communities are highly heterogeneous, and less is known about the variation in stroke across rural communities. Therefore, we sought to examine the association between rurality and hospitalization for acute ischemic stroke across rural vs urban zip codes among US census geographic regions.

Methods: We included fee-for-service Medicare beneficiaries with prevalent hypertension and/or diabetes followed from 2017 to 2021. Participants were categorized at the residential zip code level into metropolitan, micropolitan, small towns, and rural areas using Rural Urban Commuting Area Codes. Census geographic regions were categorized at the state level into Northeast, South, Midwest, and West. First hospitalization for ischemic stroke or TIA were identified using algorithms from Medicare claims. The association between rurality and stroke hospitalization was estimated in age, race, and sex adjusted models. Additional models were stratified according to census region.

Results: We included 25,915,862 participants (age 73; 45% male; 97.6% hypertension; 41.6% diabetes; 75.5% metropolitan). Hypertension prevalence was similar across RUCA codes (98%) but diabetes prevalence was slightly lower (42% vs. 39%, metropolitan vs. rural zip codes). After a mean follow-up of 3.8 years, we observed 832,567 first stroke hospitalizations. The south had a higher event rate compared to all other regions (8.79 vs. 8.17 per 1,000 person-years). In multivariable-adjusted models, compared to metropolitan zip codes, stroke risk was similar across micropolitan and small town areas but lower among rural areas. A different pattern of results was observed across geographic regions, with a higher risk for stroke across categories of rural areas in the south but not in other geographic regions (see Table).

Conclusion: The impact of rurality on stroke risk varies by geographic region, with a higher risk for stroke among rural zip codes in the south but not in other geographic regions. Further research is needed to characterize the causes of the variability in stroke risk across rural communities.