Long-Term Outcome of Colonic and Ileal Crohn's Disease: A Two-Decade Population-Based Study in Pediatric-Onset Disease.

Introduction: Crohn's disease (CD) location would influence the risk of complications and therapeutic strategies. The objective of this study was to compare the clinical presentation at diagnosis and the natural history of colonic CD in comparison to ileal CD and ulcerative colitis (UC) in pediatric-onset inflammatory bowel disease (IBD).

Patients and methods: All children (<17 years) with a diagnosis of CD or UC made between 1988 and 2011 in a population-based registry were included. The presentation at diagnosis, the risks of complications, surgery, hospitalization, and exposure to different treatments in ileal CD (CD-L1), colonic CD (CD-L2), and UC were compared.

Results: A total of 215 CD-L1 patients, 234 CD-L2 patients, and 337 UC patients were included. Over the study period, the annual incidence rates of CD-L1, CD-L2, and UC were 0.65 (95% CI, 0.57-0.74), 0.71 (0.62-0.81), and 1.02 (0.92-1.14) per 105 persons, respectively. At diagnosis, the proportion of males (L1 53%; L2 53%; UC 43%; P = .012), age at diagnosis (15.0; 13.7; 14.0 years; P = .003), family history of IBD (13%; 11%; 5%; P = .005), diagnostic delay (3.0; 3.0; 2.0 months; P = .001), and smoking prevalence (12%; 8%; 6%; P = .041) were different between the 3 groups. Bloody stools at diagnosis were observed in 15%, 44%, and 91% for, respectively, CD-L1, CD-L2, and UC (P < .001), and diarrhea in 47%, 72%, and 65% (P < .001). At diagnosis, the presence of granuloma was identified in 13% of CD-L1 patients and 31% of CD-L2 patients (P < .001). The risk of extension to L3 was significantly higher in the CD-L2 group than in the CD-L1 group (at 5 years-37% vs. 14%, P < .001). L2 location was associated with a lower risk of luminal fistula (hazard ratio [HR] 0.4 [0.2-0.6], P < .001) but was associated with a higher risk of anoperianal lesion (HR 2.1 [1.3-3.4], P = .003). The prevalence of extraintestinal manifestations, articular (P < .001) and cutaneous (P < .001), was higher in CD-L2. While the 5-year risk of surgery was significantly higher in case of CD-L1 (37%, 13%, and 13%; P < .001), the 5-year exposure to corticosteroids (55%, 69%, and 67%; P < .001), immunosuppressants (47%, 61%, and 42%; p < .001), and anti-TNF (16%, 35%, and 21%; P < .001) were higher in case of L2 location.

Conclusions: The clinical presentation and evolution of ileal and colonic CD differ significantly in children. Colonic location is associated with a high risk of perianal CD, extraintestinal manifestations, and exposure to steroids, immunosuppressants, and anti-TNFs. These differences could justify different therapeutic approaches.