Assessment of the association between red blood cell distribution width and disease activity in patients with systemic vasculitis

The present study aimed to investigate whether red blood cell distribution width (RDW) could serve as a marker for estimating disease activity in patients with systemic vasculitis (SV). A total of 287 patients with SV and 64 age- and sex-matched healthy controls (HCs) were included in the present study. Biochemical indicators and hematologic parameters were evaluated in patients with SV and the HCs. Disease activity was assessed on the basis of the Birmingham Vasculitis Activity Score (BVAS). RDW was significantly elevated in patients with SV compared with HCs (P<0.05). A similar result was obtained for the comparison of patients with various disease states, active vs. inactive (P<0.05). RDW was significantly increased in patients with kidney injury compared with patients without kidney injury (P<0.05). The correlation analysis indicated that there were positive correlations between RDW and BVAS, erythrocyte sedimentation rate, high-sensitivity C-reactive protein, white blood cells and serum creatinine (Scr; all P<0.05). In addition, there was a significant negative correlation between RDW and hemoglobin levels (P<0.05). Multivariate logistic regression analysis indicated that RDW was independently correlated with patients with active SV. The combined diagnosis of RDW and Scr indicated that the sensitivity and specificity were 68.6 and 88.9%, respectively, in terms of assessing disease activity in patients with SV. Therefore, the present study suggested that RDW may serve as a useful index for estimating disease activity and kidney injury in patients with SV. Moreover, the combination of RDW and Scr may be more effective than RDW alone when assessing the risk of disease activity in patients with SV.