Abstract MP04: Socioeconomic Spatial Social Polarization and Blood Pressure at Three Spatial Levels

Abstract

Spatial social polarization (SSP) indices measure how a population is distributed at extremes of privilege and deprivation. The choice of spatial level for analysis impacts the results of studies of SSP, resulting in a bias known as the Modifiable Areal Unit Problem (MAUP). The objective of this study is to examine the association between participant SSP with systolic and high blood pressure among Black and White adults in the CHS and REGARDS studies across three spatial levels: ZCTA, census tract, and county. We used the Index of Concentration at the Extremes (ICE) to measure SSP across socioeconomic domains including race/ethnicity, income, joint race/ethnicity with income, and home ownership using ZCTA-, census tract-, and county-level data. We computed quintiles for each geographic level, with quintile 1 representing the most deprived area and quintile 5 representing the most privileged for each SSP domain measured. High BP was defined as a treated or untreated blood pressure >140/90 mmHg. Multilevel mixed-effects regression models were adjusted for source study and a priori defined covariates with a random intercept for spatial level. The magnitude of the association between spatial privilege and blood pressure was higher at more local levels. We found that study participants who resided in the most polarized and disadvantaged quintile for race/ethnicity had an odds ratio of 1.01 (95% CI: 0.87, 1.16), 1.20 (95% CI: 1.06, 1.35), and 1.24 (95% CI: 1.09, 1.40) at the county, ZCTA, and tract level respectively for high blood pressure compared to those in the most polarized privileged groups for race/ethnicity. Similar results were found for systolic blood pressure, though results varied by the ICE domain examined. These varying effects as a result of MAUP may be functions of the larger area units not capturing the underlying granular SSP distributions of deprivation and privilege and washing out the total effects of spatial polarization on blood pressure.