Abstract Body: Background: Hypertension remains a significant public health concern, with persistent racial and gender disparities in disease burden. Residential segregation limits people’s access to resources that could promote health. We sought to investigate racial and gender differences in the association of residential segregation and risk of incident hypertension.

Methods: This analysis included Black and White participants of the REasons for Geographic And Racial Differences in Stroke study (30,239 Black and White adults from the 48 contiguous US states) who did not have hypertension at the first visit (2003-7) and completed the 2^nd visit (2013-16). County-level residential segregation was measured with the delta index, where higher scores indicate greater racial segregation. The delta index measures the concentration dimension, which depicts the relative amount of space occupied by Black people in an area. Modified Poisson regression was used to calculate risk ratios (RRs) of incident hypertension per 1-standard deviation (SD) increment delta index. Models were adjusted for age, gender, and systolic blood pressure. Racial and gender differences in the association of the delta index and hypertension risk were tested.

Results: Among the 6,894 participants, the mean (SD) age was 62 (8.4) years. The incidence of hypertension was 48% for Black women, 43% for Black men, 32% White women, and 34% White men. The risk of hypertension was 3% lower for each SD higher delta index (RR: 0.97; 95% [confidence interval] CI: 0.94-0.99). There were significant racial and gender differences in the association of the delta index and hypertension risk (Table). Black women had a 9% lower risk of hypertension per SD higher delta index (RR: 0.91; 95% CI: 0.85-0.96). The association was not significant for the other race-gender groups.

Conclusions: Our findings revealed that delta index was associated with lower risk of hypertension in Black women. Given that previous research generally reports positive associations between residential segregation and health outcomes, we need to investigate mechanisms in segregated areas that explain this negative association between the delta index and hypertension risk.