Social Predictors of Red Cell Distribution Width - An Emerging Biomarker of Disease

A growing number of studies have shown that greater variation in the size of circulating erythrocytes, as measured by the red cell distribution width (RDW), strongly predicts cardiovascular disease events, hospital stay length, and mortality. No studies have characterized RDW distribution by social factors.

Data from the 1999-2010 National Health and Nutrition Examination Surveys were analyzed, including 13,919 non-pregnant participants ≥45 years. Logistic regressions were used to predict high RDW (≥14.0) based on education, income, race/ethnicity, marital status, and emotional support needs.

Age- and gender-adjusted models using one set of social variables at a time showed poverty (vs. high income odds ratio [OR] 2.49, 95% confidence interval [CI] 2.03-3.06) and lowest education (vs. highest education OR 1.89, CI 1.49-2.40) were associated with increased odds of high RDW. Mexican-Americans (OR 1.26, CI 1.02-1.57), non-Mexican Hispanics (OR 1.56, CI 1.10-2.21), and black non-Hispanics (OR 4.26, CI 3.61-5.01) were also more likely to have a high RDW compared with white non-Hispanics. Never married (OR 2.06, CI 1.63-2.62), divorced/separated (OR 1.53, CI 1.32-1.79), and widowed (OR 1.42, CI 1.18-1.70) participants' odds were increased compared with married people, as were those with low emotional support compared with high support (OR 1.62, CI 1.14-2.31). Many effects remained in a saturated model.

We observed a social gradient in RDW with disadvantaged populations having greater variation in red blood cell sizes than those with greater resources, as well as race/ethnicity effects. RDW is an inexpensive biomarker that may provide a new physiologic subsystem to investigate how social factors “get under the skin.”