Objective: Health administrative databases can be used to track chronic diseases. We aimed to validate a case ascertainment definition of paediatric-onset IBD using administrative data and describe its epidemiology in Ontario, Canada.
Design: We used a population-based clinical database of IBD patients <15y to define cases and linked patient information to health administrative data to compare the accuracy of various patterns of healthcare use. We validated the most accurate algorithm with chart data of children <18y from twelve medical practices. We used administrative data from 1991-2008 to describe incidence and prevalence of IBD in Ontario children. We tested changes in incidence using Poisson regression.
Results: Accurate identification of children with IBD required 4 physician contacts or 2 hospitalizations (with ICD codes for IBD) within 3 years if they underwent colonoscopy and 7 contacts or 3 hospitalizations within 3 years in those without colonoscopy (<12 year old children: sensitivity 90.5%, specificity >99.9%, <15y old children: sensitivity 89.6%, specificity >99.9%, <18y old children: sensitivity 91.1%, specificity 99.5%). Age- and sex-standardized prevalence per 100,000 population of paediatric IBD has increased from 42.1 (in 1994) to 56.3 (in 2005). Incidence per 100,000 has increased from 9.5 (in 1994) to 11.4 (in 2005). Statistically significant increases in incidence were noted in 0-4 year olds (5.0%/year, p=0.03) and 5-9 year olds (7.6%/year, p<0.0001), but not in 10-14 or 15-17 year olds.
Conclusion: Ontario has one of the highest rates of childhood-onset IBD in the world, and there is an accelerated increase in incidence in younger children.