Residential ethnic segregation and stroke risk in Mexican Americans: the Brain Attack Surveillance in Corpus Christi project.

OBJECTIVE Residential ethnic segregation may operate through multiple mechanisms to increase stroke risk. The current study evaluated if residential ethnic segregation was associated with stroke risk in a bi-ethnic population. DESIGN Incident strokes were identified in Nueces County, Texas from 2000 to 2010. Residential ethnic segregation (range: 0-1) was derived for each census tract in the county (n=64) using 2000 US Census data, and categorized into: predominantly non-Hispanic White (NHW, <.3); ethnically mixed (.3-.7); predominantly Mexican American (MA, >.7). Multilevel Poisson regression models were fitted separately for NHWs and MAs to assess the association between residential ethnic segregation (predominantly NHW referent) and relative risk for stroke, adjusted for age category, sex and census tract-level median per capita income. Effect modification by age was also examined. RESULTS In adjusted models, residential ethnic segregation was not associated with stroke risk in either ethnic group. Effect modification by age was significant in both groups. Young MAs and NHWs living in predominantly MA census tracts were at greater relative risk for stroke than those living in predominantly NHW census tracts, but this association was only significant for MAs (MAs: RR = 2.38 [95% CI: 1.31-4.31]; NHWs: RR = 1.53 [95% CI: .92-2.52]). CONCLUSION Our findings demonstrate that residential ethnic segregation may influence downstream stroke risk in young MAs. Pathways between residential ethnic segregation and stroke in young MAs should be explored.