Association between spatial social polarisation and high blood pressure in older adults.

Background: Using data from the Cardiovascular Health Study (CHS) and the REasons for Geographic And Racial Differences in Stroke (REGARDS) study, we investigate the association between socioeconomic polarisation and blood pressure outcomes in black and white adults. We also validate previous findings that joint racial/ethnic and income measures of spatial social polarisation (SSP) outperform single domain measures.

Methods: We conducted a cross-sectional analysis using a retrospective cohort combining CHS (recruited 1989-1990 and 1992-1993) and REGARDS (recruited 2003-2007). The study included 5888 CHS participants aged ≥65 years and 30 183 REGARDS participants aged ≥45 years. SSP was measured using the Index of Concentration at the Extremes for education, race/ethnicity, income, home ownership, and joint race/ethnicity and income at ZIP code, census tract and county levels. The SSP measures were modelled against the presence of high blood pressure and systolic blood pressure.

Results: The sample had a mean age of 66 (SD: 9), was majority female (56%), white/other (63%), and at least high school graduates (85%). A total of 26% had high blood pressure, with a mean systolic blood pressure of 129 mm Hg (SD: 18). Census tract-level models showed low-income black areas had 25% (95% CI 11%-40%) higher odds of high blood pressure and 1.8 mm Hg (95% CI 1.0-2.5) higher mean systolic blood pressure than high-income White areas.

Conclusion: Greater SSP is associated with a higher risk of high blood pressure and higher systolic blood pressure. Further investigating and reducing polarisation could help mitigate cardiovascular health disparities, improving outcomes for socioeconomically deprived communities.