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

Background and Aim Pediatric inflammatory bowel disease ( IBD ) has not been rare in J apan since the 1990s. The present study attempted to define the epidemiological and clinical characteristics of early‐childhood IBD in J apan in comparison with results from W estern countries. Methods Among children diagnosed as having IBD between J anuary 1998 and D ecember 2008, those showing onset before 8 years of age were investigated retrospectively. A questionnaire survey was carried out at 45 facilities throughout J apan, and 80 cases were reported from 27 facilities. On the basis of the final diagnosis, 24 patients with C rohn'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 M ontreal 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 relatives was 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 J apan, the pathogenesis of IBD in infants and children may differ from that in W estern countries, and that the characteristics of early childhood‐onset IBD are distinct from those of school age‐onset IBD .