Background — International cohort studies have reported increased incidence of inflammatory bowel disease (IBD) in recent years, and Canada has amongst the highest rates of IBD in the world. This study assessed incidence and prevalence of IBD in Ontario, Canada’s most populous province, to determine changing trends in age of onset.
Methods — The researchers used a population-based cohort derived from validated health administrative data consisting of all Ontario residents living with IBD from 1999-2008. The researchers determined trends over time using Poisson regression analysis, assessing 10-year (y) age groups, rates in children, adults, and the elderly.
Results — In 2008, 68,071 people were living with IBD amongst 12,738,350 people (standardized prevalence 534.3 per 100,000 people). Between 1999-2008, standardized IBD incidence increased from 21.3 to 26.2 per 100,000 (2.3%/y, P<0.0001). Incidence of Crohn’s increased from 9.6 to 12.1 per 100,000 (1.9%/y, P<0.0001). Ulcerative colitis incidence increased from 10.7 to 12.1 per 100,000 (2.0%/y, P<0.0001). For IBD, incidence increased significantly in people <10y (9.7%/y, P<0.0001), and 10-19y (3.8%/y, P<0.0001), 30-39y (1.8%/y, P=0.0006), 40-49y (2.8%/y, P=0.0001), and 50-59y (2.8%/y, P<0.0001). Incidence was stable in patients >65y at diagnosis (-0.1%/y, P=0.73). While incidence did not change significantly over time in adults 20-29y, IBD incidence peaked in this age group.
Conclusions — Ontario has amongst the highest prevalence of IBD in the world. Incidence of IBD increased between 1999-2008, owing to increased incidence in children and adults, with stable rates in elderly people. These findings demonstrate the changing age demographics and growing burden of IBD in Ontario, Canada.