Exploring the Spatial Patterning in Racial Differences in Cardiovascular Health Between Blacks and Whites Across the United States: The REGARDS Study

Abstract

Background Cardiovascular health (CVH) disparities between blacks and whites have persisted in the United States for some time, and although there have been remarkable improvements in addressing cardiovascular disease, it still remains the leading cause of death in the United States. In addition, well-documented disparities are unfortunately widening incidence gaps across certain regions of the United States. Our focus was on answering the following questions: (1) How much spatial heterogeneity exists in the racial differences in CVH between blacks and whites across this country? and (2) Is the spatial heterogeneity in the racial differences significantly explained by living in the Stroke Belt? Methods and Results To explore the spatial patterning in the racial differences in CVH between blacks and whites across the country, we used geographically weighted regression methods, which result in local estimates of the racial differences in CVH. Using data from the REGARDS (Reasons for Geographic and Racial Differences in Stroke) Study, we found significant spatial patterning in these racial differences, even beyond the well-known Stroke Belt and Stroke Buckle. All of the estimated differences indicated blacks consistently having diminishing CVH compared with whites, where this difference was largely noted in pockets of the Stroke Belt and Stroke Buckle, in addition to moderate to large disparities noted in the Great Lakes region, portions of the Northeast, and along the West coast. Conclusions Efforts to improve CVH and ultimately reduce disparities between blacks and whites require culturally competent methods, with a strong focus on geography-based interventions and policies.

Keywords: biostatistics; cardiovascular outcomes; disparities; geographically weighted regression; regression; spatial patterning.

Figure 1. Flowchart displaying inclusion and exclusion criteria for the examination of the spatial heterogeneity in racial differences in cardiovascular health (CVH) in the REGARDS (Reasons for Geographic and Racial Differences in Stroke) Study, 2003 to 2007.

Figure 2. Geographically weighted regression (GWR) results of total cardiovascular health (CVH) scores for blacks (A) and whites (B) for the REGARDS (Reasons for Geographic and Racial Differences in Stroke) Study participants residing across the United States (N^Black=5811; N^White=12 078).

Figure 3. Geographically weighted regression (GWR) results for the effect of race (blacks vs whites) on total cardiovascular health score for the REGARDS (Reasons for Geographic and Racial Differences in Stroke) Study participants residing across the United States (N=17 889).

Maps represent model results before (A) vs after (B) controlling for the Stroke Belt region.