Socioeconomic indices as independent correlates of C-reactive protein in the National Longitudinal Study of Adolescent Health.

Objectives: To examine the association between socioeconomic status (SES) and C-reactive protein (CRP) to understand how SES may increase the risk of cardiovascular disease and thus identify targets for prevention measures.

Methods: Path models were used to examine direct and indirect associations of four indices of SES (objective early life built environment ratings, parental and participant education, and income) with CRP measured during early adulthood using data from the National Longitudinal Adolescent Health Study (n = 11,371; mean age = 29 years, range = 24-32 years; 53.8% women, 28.0% black participants). The present study examined potential mediation of the association of SES with CRP by way of body mass index (BMI), smoking, and alcohol consumption within white and black men and women.

Results: BMI was a mediator of the relation between parent education and CRP for white men (path coefficient [γ] = -0.05, p < .001) and women (γ = -0.05, p < .001). Smoking mediated the income-CRP (γ = -0.01, p < .01) and the education-CRP (γ = -0.07, p < .001) relation for white men. BMI mediated the relation between all measures of SES and CRP for white women (γ values between -0.02 and -0.05; p values < .01). None of the risk factors mediated the SES-CRP relation in black participants.

Conclusions: These findings indicate that the association of SES with CRP is influenced by both the timing and type of SES measure examined. In addition, race and sex play a role in how potential mediators are involved with the SES-CRP relationship, such that BMI and smoking were mediators in white men, whereas BMI was the sole mediator in white women.