Association of socioeconomic status with inflammation markers in black and white men and women in the Coronary Artery Risk Development in Young Adults (CARDIA) study

Abstract

Inflammatory processes are implicated in a number of diseases for which there are known socioeconomic status (SES) disparities, including heart disease and diabetes. Growing evidence also suggests SES gradients in levels of peripheral blood markers of inflammation. However, we know little about potential gender and racial/ethnic differences in associations between SES and inflammation, despite the fact that the burden of inflammation-related diseases varies by gender and race. The present study examines SES (education and income) gradients in levels of two inflammatory biomarkers, C-reactive protein (CRP) and interleukin-6 (IL-6), in a biethnic (White and Black) sample of men and women (n=3549, aged 37-55 years) in the USA from the CARDIA Study. Health status, behavioral and psychosocial variables that may underlie SES differences in inflammatory biomarker levels were also examined. Age-adjusted CRP and IL-6 levels were inversely associated with education level in each race/gender group except Black males. Income gradients were also observed in each race/gender group for IL-6 and in White females and males for CRP. In general, differences in CRP and IL-6 levels between low and high SES groups were reduced in magnitude and significance with the addition of health status, behavioral, and psychosocial variables, although the impact of the addition of model covariates varied across race/gender groups and different SES-inflammation models. Overall, findings indicate SES gradients in levels of inflammation burden in middle-aged White and Black males and females.

Figure 1

Age-adjusted geometric mean levels of CRP and IL-6 by level of education and income.