title: Changing age demographics of inflammatory bowel disease in Ontario, Canada: a population-based cohort study of epidemiology trends.
abstract: BACKGROUND
  International cohort studies have reported increased incidence of inflammatory bowel disease (IBD) in recent years, and Canada has among the highest rates of IBD in the world. This study assessed incidence and prevalence of IBD in Ontario, the most populous province of Canada, to determine changing trends in age of onset.
  
  
  METHODS
  We used a population-based cohort derived from validated health administrative data consisting of all Ontario residents living with IBD from 1999 to 2008. We determined trends over time using Poisson regression analysis, assessing rates in 10-year age groups, children, adults, and the elderly.
  
  
  RESULTS
  In 2008, 68,071 people were living with IBD among 12,738,350 people (standardized prevalence 534.3 per 100,000 people). Between 1999 and 2008, standardized IBD incidence increased from 21.3 to 26.2 per 100,000 (2.3% per yr, P < 0.0001). Incidence of Crohn's increased from 9.6 to 12.1 per 100,000 (1.9% per yr, P < 0.0001). Ulcerative colitis incidence increased from 10.7 to 12.1 per 100,000 (2.0% per yr, P < 0.0001). For IBD, incidence increased significantly in people younger than 10 years of age (9.7% per yr, P < 0.0001), 10 to 19 years of age (3.8% per yr, P < 0.0001), 30 to 39 years of age (1.8% per yr, P = 0.0006), 40 to 49 years of age (2.8% per yr, P = 0.0001), and 50 to 59 years of age (2.8% per yr, P < 0.0001). Incidence was stable in patients older than 65 years of age at diagnosis (-0.1% per yr, P = 0.73). Although incidence did not change significantly over time in adults 20 to 29 years, IBD incidence peaked in this age group.
  
  
  CONCLUSIONS
  Ontario has among the highest prevalence of IBD in the world. Incidence of IBD increased between 1999 and 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.
authors.affiliation: *CHEO Inflammatory Bowel Disease Centre, Division of Gastroenterology, Hepatology and Nutrition, Children's Hospital of Eastern Ontario, Ottawa, ON, Canada; †Institute for Clinical Evaluative Sciences, Toronto, ON, Canada; Departments of ‡Pediatrics, §Epidemiology and Community Medicine, and ‖Family Medicine, University of Ottawa, Ottawa, ON, Canada; ¶Ottawa Hospital Research Institute, Ottawa, ON, Canada; **Department of Pediatrics, University of Toronto, Toronto, ON, Canada; ††Institute of Health Policy, Management and Evaluation, University of Toronto, Toronto, ON, Canada; ‡‡Department of Medicine, University of Toronto, Toronto, ON, Canada; and §§Mount Sinai Centre for Inflammatory Bowel Disease, Toronto, ON, Canada.
authors.forename: Eric I
authors.initials: EI
authors.lastname: Benchimol
authors.forename: Douglas G
authors.initials: DG
authors.lastname: Manuel
authors.forename: Astrid
authors.initials: A
authors.lastname: Guttmann
authors.forename: Geoffrey C
authors.initials: GC
authors.lastname: Nguyen
authors.forename: Nassim
authors.initials: N
authors.lastname: Mojaverian
authors.forename: Pauline
authors.initials: P
authors.lastname: Quach
authors.forename: David R
authors.initials: DR
authors.lastname: Mack
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D003710:Demography; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D015212:Inflammatory Bowel Diseases / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D009864:Ontario / Q000453:epidemiology; D011379:Prognosis; D012189:Retrospective Studies; D012307:Risk Factors; D055815:Young Adult