Characteristics of inflammatory bowel disease with an onset before eight years of age: A multicenter epidemiological survey in Japan

Background and Aim Pediatric inflammatory bowel disease (IBD) has not been rare in Japan since the 1990s. The present study attempted to define the epidemiological and clinical characteristics of early-childhood IBD in Japan in comparison with results from Western countries. Methods Among children diagnosed as having IBD between January 1998 and December 2008, those showing onset before 8 years of age were investigated retrospectively. A questionnaire survey was carried out at 45 facilities throughout Japan, and 80 cases were reported from 27 facilities. On the basis of the final diagnosis, 24 patients with Crohn's disease (CD) and 47 patients with ulcerative colitis (UC) were analyzed. Results Among the patients with CD, the age at onset was less than 1 year in 62.5%. On the basis of the Montreal classification, 87.5% of CD cases involved the colon, and 63.8% of UC cases were pancolitis. Coexisting conditions such as congenital diseases(five cases) and cerebral palsy (four cases) were present before the onset of IBD. Growth failure was more severe (P < 0.05) at diagnosis in CD patients than in UC patients. Familial occurrence within first-degree relativeswas observed in eight families among 45 patients with UC, compared with none among the CD patients (P < 0.05). Conclusion Our results suggest that, in Japan, the pathogenesis of IBD in infants and children may differ from that in Western countries, and that the characteristics of early childhood-onset IBD are distinct from those of school age-onset IBD.