Association Between Red Cell Distribution Width and Disease Activity in Patients with Inflammatory Bowel Disease

Recent studies have suggested that a higher red blood cell distribution width (RDW) is associated with disease activity in patients with inflammatory bowel disease (IBD). However, the RDW in IBD patients without anemia has not been investigated. This study aimed to determine whether or not RDW could be used for the assessment of disease activity in IBD patients with and without anemia. The serum C-reactive protein (CRP) level, erythrocyte sedimentation rate (ESR), hemoglobin concentration, platelet and white blood cell counts, and RDW were assessed in 221 IBD patients, comprised of 120 patients with ulcerative colitis (UC) and 101 patients with Crohn's disease (CD). Disease activity was determined for UC and CD with the Mayo score and the Crohn's disease activity index, respectively. The CRP level, ESR, hemoglobin concentration, hematocrit, and RDW increased according to disease activity in patients with and without anemia (all P < 0.05). Multivariate analysis demonstrated that RDW was the best independent indicator for predicting disease activity in CD patients without anemia [odd ratios (OR), 1.702; 95% confidence interval (CI), 1.185-2.445; P = 0.004] and UC patients without anemia (OR, 4.921; 95% CI, 2.281-10.615; P < 0.001). Also, ROC curve analysis showed the RDW to be the most significant indicator of non-anemic active IBD [area under curve (AUC) in CD, 0.852, P < 0.001; AUC in UC, 0.827, P < 0.001]. The association between increased RDW and active IBD was evident in IBD patients with and without anemia.