Heterogeneity in disparities by income in cardiovascular risk factors across 209 US metropolitan areas.

Objective: The United States has a lower life expectancy and wider income inequality than its similarly developed counterparts, and disparities continue to widen. The objective of our study is to examine the heterogeneity of disparities by income in cardiovascular disease (CVD) risk factors among U.S. metropolitan areas. Methods: Data was obtained from the Behavioral Risk Factor Surveillance System for 2012-2019. We used self-reported data for respondent characteristics and for CVD risk factors/prevalence, and on metropolitan-level demographic and socioeconomic characteristics. We computed the relative index of inequality (RII) for each outcome using a multilevel Poisson model, sequentially adjusted for age, sex, and race/ethnicity with a random slope for income. We also included interactions between income and the metropolitan-level variables. Results: Our sample included 1.4 million participants from 209 metropolitan areas. All CVD risk factors and CVD demonstrated income-related disparities. There were no clear regional patterns for risk factors, though seven of the top 10 large metropolitan areas with the widest disparities in CVD prevalence were in the South. Improved socioeconomic conditions were associated with wider disparities in the five risk factors, and contextual variables explained almost half of the variability in income disparities in smoking, sedentarism, and obesity, even after adjusting for age, sex, and race/ethnicity. Conclusions: This study found that CVD risk factors and prevalence in U.S. metropolitan areas have heterogeneous income disparities, especially in advantaged metropolitan areas. Further studies with improved data collection may shed more light into potential drivers of income-based disparities in cardiovascular risk.