INFLAMMATORY bowel disease (IBD) evaluation could be strengthened by incorporating red blood cell distribution width (RDW), after a systematic review and meta-analysis found the routinely available blood parameter was consistently associated with disease presence, activity, and severity across IBD populations.
Inflammatory markers are commonly used when assessing IBD. RDW has previously been proposed as a potential biomarker, although uncertainty has remained regarding its clinical value. To evaluate the available evidence, researchers conducted a systematic review and meta-analysis following PRISMA guidance. Searches of major medical databases included studies published up to 4 September 2025, with extracted data examining the role of RDW in IBD detection and its relationship with disease activity. Statistical analyses used a random effects model, with subgroup analyses according to disease activity.
The analysis found that RDW was significantly higher in patients with Crohn’s disease and ulcerative colitis than in healthy controls. Results were as follows: Crohn’s disease (mean difference: 2.2; p<0.001); ulcerative colitis (mean difference: 1.36; p<0.001).
Higher RDW values were also consistently associated with active disease compared with remission. In Crohn’s disease, the mean difference was 1.29 (p<0.001), while ulcerative colitis showed a mean difference of 1.11% (p<0.001). In addition, active Crohn’s disease demonstrated significantly higher RDW than active ulcerative colitis (mean difference: 0.59; p<0.005).
For identifying active Crohn’s disease rather than remission, a RDW threshold above 14% achieved the following diagnostic performance: sensitivity: 0.86; specificity: 0.78; area under the curve: 0.83.
The findings suggested that RDW was consistently associated with both IBD activity and disease severity. Given that the measurement is widely available and inexpensive, the investigators concluded it could represent a practical biomarker to support evaluation of IBD.
The authors highlighted that RDW demonstrated reliable diagnostic performance across the analysed studies, particularly with regard to distinguishing active Crohn’s disease from remission. These findings support further consideration of RDW as an accessible addition to routine IBD assessment alongside established clinical evaluation.
Reference
Khalil Y et al. “The role of red cell distribution width in inflammatory bowel disease evaluation: a comprehensive systematic review and meta-analysis”. BMC Gastroenterol. 2026;26(1):475
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