Perianal Disease Modifiers Are Associated With Less Severe Luminal Disease Activity in Children With Crohn's Disease at Diagnosis.

BACKGROUND: There is lack of data regarding the associations between perianal fistulizing disease and other disease characteristics at diagnosis in children with Crohn's disease (CD). We sought to investigate the associations between perianal fistulizing disease and other disease characteristics at diagnosis in children with CD. METHODS: This was a multicenter, registry-based, inception cohort study conducted in Korea. Children newly diagnosed with CD were included. Baseline clinicodemographics; results from laboratory, endoscopic, histologic exams; and Paris classification factors were collected, and associations between factors were investigated. RESULTS: A total 699 patients were included. The median age at diagnosis was 14.3 years (IQR, 12.3-15.9 years), and the male-to-female ratio was 2.66:1. Perianal disease modifiers comprised 50.6% (n = 354 of 699) of the patients. The proportion of perianal disease modifiers was higher in males (81.1% vs 64.1%; P < .001), in those with upper gastrointestinal tract involvement (85.3% vs 75.7%; P = .002), and in those with B1 behavior (89.5% vs 79.7%; P < .001). Albumin was higher (P = .006) and CRP was lower (P < .001) in patients with perianal disease modifiers. Females had a higher proportion of B2/B3 behavior (21.4% vs 14.4%; P = .029), higher Pediatric Crohn's Disease Activity Index scores (median 40 vs 32.5; P < .001), higher CRP (P = .017), higher Simple Endoscopic Score for Crohn's Disease scores (P = .01), and more frequent detection of noncaseating granulomas in the lower gastrointestinal tract (P = .008). CONCLUSIONS: Perianal fistulizing disease was more common in boys who exhibited milder disease activity, indicating the importance of recognizing perianal fistulizing disease as a clinical clue to the early diagnosis of underlying luminal CD.