Red cell distribution width: a novel marker of activity in inflammatory bowel disease

Studies concerning red cell distribution width (RDW) for use in the assessment of inflammatory bowel disease (IBD) activity are limited. We investigated whether RDW is a marker of active disease in patients with IBD.

In total, 61 patients with ulcerative colitis (UC) and 56 patients with Crohn's disease (CD) were enrolled in the study group, and 44 age- and-sex-matched healthy volunteers were included as the control group. A CD activity index >150 in patients with CD indicated active disease. Patients with moderate and severe disease based on the Truelove-Witts criteria were considered to have active UC. In addition to RDW, serum C-reactive protein levels, erythrocyte sedimentation rates, and platelet counts were measured.

Twenty-nine (51.7%) patients with CD and 35 (57.4%) patients with UC had active disease. The RDW was significantly higher in patients with CD and UC than in controls (p<0.001 and p<0.001, respectively). A subgroup analysis indicated that for a RDW cut-off of 14%, the sensitivity for detecting active CD was 79%, and the specicity was 93% (area under curve [AUC], 0.935; p<0.001). RDW was the most sensitive and specific marker for active CD. However, it was not valid for UC, as the ESR at a cutoff of 15.5 mm/hr showed a sensitivity of 83% and a specicity of 76% (AUC, 0.817; p<0.001), whereas the RDW at a cutoff of 14% showed 17% sensitivity and 84% specicity for detecting active UC.

RDW was elevated in IBD in comparison with healthy controls and increased markedly in active disease. RDW may be a sensitive and specific marker for determining active CD, whereas ESR is an important marker of active UC.