Socioeconomic Position, Race/Ethnicity, and Inflammation in the Multi-Ethnic Study of Atherosclerosis

Socioeconomic Position, Race/Ethnicity, and Inflammation in the Multi-Ethnic Study of AtherosclerosisNalini Ranjit, PhD; Ana V. Diez-Roux, MD, PhD; Steven Shea, MD, MS; Mary Cushman, MD, MSc; Hanyu Ni, PhD, MPH; Teresa Seeman, PhD
From the Center for Social Epidemiology and Population Health, University of Michigan, Ann Arbor (N.R., A.V.D.-R.); Departments of Medicine and Epidemiology, Columbia University, New York, NY (S.S.); Department of Medicine, University of Vermont, Burlington (M.C.); Division of Epidemiology and Clinical Applications, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Md (H.N.); and Division of Geriatrics, School of Medicine, University of California at Los Angeles (T.S.).
Correspondence to Nalini Ranjit, 1214 S University, University of Michigan, Ann Arbor, MI 48104. E-mail nranjit@umich.edu
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Received March 29, 2007; accepted August 17, 2007.
Background— Low socioeconomic position is known to be associated with cardiovascular events and atherosclerosis. Reasons for these associations remain a topic of research. Inflammation could be an important mediating mechanism linking socioeconomic position to cardiovascular risk.
Methods and Results— This cross-sectional study used data from the baseline examination of the Multi-Ethnic Study of Atherosclerosis (MESA), a study of 6814 men and women 45 to 84 years of age. Race- and ethnicity-stratified regression analyses were used to estimate associations of household income and education with C-reactive protein and interleukin-6 before and after adjustment for infection and medication use, psychosocial factors, behaviors, adiposity, and diabetes mellitus. Low income was associated with higher concentrations of interleukin-6 in all race/ethnic groups. Percent differences associated with 1-SD–lower income were 9% (95% confidence interval [CI], 7 to 11), 6% (95% CI, 1 to 10), 8% (95% CI, 4 to 11), and 8% (95% CI, 3 to 13) for whites, Chinese, blacks, and Hispanics. Low levels of education were associated with higher levels of interleukin-6 only among whites and blacks (percent difference in interleukin-6 associated with 1-SD–lower education: 9% [95% CI, 6 to 12] among Whites, and 7% [95% CI, 3 to 10] among blacks). Similar patterns were observed for C-reactive protein. Adiposity was the single most important factor explaining socioeconomic position associations, especially among blacks and whites. A smaller effect was seen for psychosocial factors and behaviors in all race groups.
Conclusions— Both household income and education are associated with inflammation, but associations vary across race/ethnic groups. Associations likely result from socioeconomic position patterning of adiposity and other factors.