A prospective study was undertaken throughout Wales over the period from 1 January 1995 to 30 March 1997, to determine the incidence of childhood inflammatory bowel disease (IBD). Thirty-eight (24 male) new cases of IBD were reported. Twenty (16 male) of the reported cases had Crohn's disease, 11 (5 male) had ulcerative colitis (UC) and 7 (3 male) indeterminate colitis. Crohn's disease occurred four times more often in boys than girls, whereas there was no sex difference in the incidence for UC and indeterminate colitis. The median age at presentation was 12 (range 1.5-16) years and there was no difference in the age of presentation or the duration of symptoms prior to diagnosis in any of the types of IBD.
Conclusion: The overall incidence (95% confidence intervals) for IBD in Wales was 2.6 (1.87-3.48) cases per 100,000 per year. The incidence for Crohn's disease was 1.36 (0.86-2.04) cases per 100,000 per year, for UC 0.75 (0.39-1.28) cases per 100,000 per year and for indeterminate colitis 0.48 (0.2-0.92) cases per 100,000 per year.