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

Background/aims: 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.

Methods: 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.

Results: 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.

Conclusions: 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.