Inflammatory bowel disease in children: epidemiological analysis of the nationwide IBD registry in Japan

Objective We analyzed the database of the Japanese nationwide inflammatory bowel disease (IBD) registry, which was started in 1975, to characterize basic epidemiological and clinical features of childhood IBD, comparing them to those in adults. Study design We analyzed the age of disease onset, disease severity and anatomical distribution in patients that were newly registered between 2003 and 2006 (n = 2,940 for CD and 14,857 for UC). We also analyzed the current age, gender and family history of IBD of all patients filed in 2005, which included patients who were newly registered in 2005 and those who had been registered before 2005 and for whom an annual report had been received in 2005 (total number of subjects: 10,934 for CD and 37,846 for UC). Results At the time of registration, 10.6% of CD and 5.9% of UC patients were >= 16 years old. In CD, the male to female ratio was 2.6 in adult-and 1.7 in childhood-onset patients (P < 0.001). In UC, the male to female ratio was close to 1 in both age groups. In comparison with adults, pediatric patients more commonly had a positive family history for CD and UC (P < 0.001), tended to have more severe disease at the time of registry (P < 0.001 for CD, P < 0.05 for UC) and more often had extensive colitis in UC (P < 0.001). Conclusion The nationwide registry in Japan showed IBD in children has clinical features that are distinct from those in adults.