Background: There is limited data regarding the disease phenotype of paediatric Crohn's disease (CD) patients in the Asian population. We aimed to investigate the disease phenotype of Korean paediatric CD patients at diagnosis according to the Paris classification by comparison with patients from the EUROKIDS registry.
Methods: Paediatric CD patients who were newly diagnosed before 18 years-old from 9 tertiary medical centers in Korea during January 2013 to October 2016 were included in this retrospective study. Medical charts were reviewed and disease phenotype at diagnosis was classified according to the Paris classification. Regarding disease phenotype, only the patients who had conducted a complete diagnostic workup of the entire gastrointestinal (GI) tract were included. A complete workup required ileocolonoscopy, upper GI endoscopy, and small bowel imaging by at least one of the following modalities; magnetic resonance enterography, computed tomography enterography, capsule endoscopy. Comparison was performed by utilizing data from the previously published 5-year analysis of the EUROKIDS registry .
Results: A total 230 subjects [150 males (M), 80 females (F)] were included. The median age at diagnosis was 14.7 years (range: 1.2–17.9). No significant difference was observed in M:F ratio compared with EUROKIDS (1.88:1 vs. 1.46:1, p=0.088). A complete workup was done in 213 subjects. The proportion of children <10 years (A1a) was significantly lower in Koreans (6.6% vs. 19.6%, p<0.001). Colonic disease was less prominent (9.9% vs. 27.3%, p<0.001), while upper GI involvement was more prominent in Korean children (60.1% vs. 46.2%, p<0.001). Although no significant difference was observed in luminal disease behaviour, the proportion with perianal modifiers were significantly higher in Korean patients (46.5% vs. 8.2%, p<0.001). Meanwhile, a first-degree family history of inflammatory bowel disease was significantly lower in Korean children (4.8% vs. 10.8%, p=0.005).
Conclusions: Newly diagnosed paediatric CD patients in Korea are more likely to present at an older age, with more ileocolonic and upper GI tract involvement, and perianal fistulas and/or abscesses, compared to their counterparts in Europe. An underlying genetic difference between races may play a role in the different expression of phenotypes in paediatric CD.
 Charlotte I. de Bie, (2013), Disease Phenotype at Diagnosis in Pediatric Crohn's Disease: 5-year Analyses of the EUROKIDS Registry, Inflamm Bowel Dis