Patients with inflammatory bowel disease (IBD) who also have elevated blood eosinophil levels are more likely to have an aggressive form of the disease suggests an registry analysis of IBD patients from 2009 to 2014.

• Among more than 2,000 patients with IBD, 19.2% developed peripheral blood eosinophilia.
• Elevated eosinophil levels were significantly associated with ulcerative colitis, extensive colitis, and shorter disease duration.
• Patients with peripheral blood eosinophilia also had more active disease, as measured over a 6-year period, suggesting that eosinophilia can serve as a useful biomarker for aggressive IBD.