Relation Between Red Blood Cell Distribution Width and Inflammatory Biomarkers in a Large Cohort of Unselected Outpatients

Context.-A strong independent association has been recently observed between elevated red blood cell distribution width (RDW) and increased incidence of cardiovascular events. Objective.-To assess whether RDW is associated with plasma markers of inflammation since the mechanism(s) underlying this association remain unknown. Design.-We retrospectively analyzed results of RDW, hemoglobin, mean corpuscular volume, ferritin, high-sensitivity C-reactive protein (hsCRP), and erythrocyte sedimentation rate (ESR) in a large cohort of unselected adult outpatients who were consecutively referred by general practitioners for routine medical check-up. Results.-Cumulative results of RDW and other factors were retrieved from the database of our laboratory information system for 3845 adult outpatients during a 3-year period. When participants were grouped according to RDW quartiles, there were strong, graded increases of ESR and hsCRP (P < .001), both parameters being up to 3-fold higher in the fourth versus the first quartile. Accordingly, the percentages of those with hsCRP greater than 3 mg/L (from 28% to 63%; P < .001) and ESR greater than 40 mm/h (from 8% to 40%; P < .001) increased steadily across RDW quartiles. In multivariable regression analysis, ESR and hsCRP predicted RDW independently of age, sex, mean corpuscular volume, hemoglobin, and ferritin. Conclusions.-To our knowledge, our study demonstrates for the first time a strong, graded association of RDW with hsCRP and ESR independent of numerous confounding factors. If confirmed in future follow-up studies, this association might provide a rationale to introduce the easy, inexpensive RDW in algorithms for cardiovascular risk prediction.