Rapid rise in incidence of Irish paediatric inflammatory bowel disease.

Aims: To describe the change in incidence of paediatric inflammatory bowel disease (IBD) observed at the National Centre for Paediatric Gastroenterology, Hepatology and Nutrition, and to determine whether the presenting disease phenotype and disease outcomes have changed during the past decade.

Methods: The annual incidence of IBD in Irish children aged <16 years was calculated for the years 2000-2010. Two subsets of patients, group A (diagnosed between 1 January 2000 and 31 December 2001), and group B (diagnosed between 1 January and 31 December 2008) were phenotyped according to the Paris Classification. Phenotype at diagnosis and 2-year follow-up were then compared.

Results: 406 new cases of IBD were identified. The incidence was 2.5/100 000/year in 2001, 7.3 in 2008 and 5.6 in 2010, representing a significant increase in the number of new cases of Crohn's disease (CD) and ulcerative colitis (UC). There were 238 cases of CD; 129 of UC; and 39 of IBD unclassified. Comparing groups A and B, no differences were found in disease location at diagnosis or, for CD, in its behaviour.

Conclusions: There has been a substantial and sustained increase in the incidence of childhood UC and CD in Ireland over a relatively short period of time. However, disease phenotype at diagnosis has not changed. At 2 years follow-up, CD appears to progress less frequently than in some neighbouring countries. These variations remain unexplained. Prospective longitudinal studies will help to elucidate further the epidemiology of childhood IBD.