Incidence Trends for Crohnʼs Disease and Ulcerative Colitis in the Province of Québec, Canada

Abstract

Purpose: Among 10 provinces in Canada, Québec has the second highest incidence of Crohn's disease (CD), based on data collected more than a decade ago. To date, there are no reports on the occurrence of ulcerative colitis (UC), and no updates on the occurrence of CD in Québec. The aim of the present study is to describe trends in the annual incidences of CD and UC in Québec during 2001-2008. Methods: A population-based retrospective cohort study was conducted using the provincial administrative health databases of Québec, a Canadian province with about 7 million inhabitants. Individuals with CD and UC were identified over the 1996-2009 period using a new validated case definition, which requires at least one hospitalization or four physician claims with the CD or UC diagnosis within a two-year period. Incident cases were defined as individuals who had been free of IBD for at least two years prior to the two-year time span of the case definition, and who met the criteria in the year they were counted as incident. Annual incidence rates (IR) were calculated for 2001-2008, standardized for age and sex by the 2001 Québec Census population. A test for trend was performed to assess whether annual changes in incidence were significant. Results: We identified 24,400 CD cases and 15,421 UC cases that fulfilled all criteria of the case definition, although 240,937 individuals had at least one diagnosis code of CD or UC. The mean age at diagnosis was 39 and 46 for CD and UC, respectively. The IR for the 2001-2008 period was 17.9 CD cases/100,000 person-years (p-y), and 10.4 UC cases/100,000 p-y. The highest IR for CD was 30/100,000 p-y and was observed in the 20-29 year old group. The highest IR for UC was 13.5/100,000 p-y and was observed in the 30-39 year old group. The annual IR are presented in the Table. The test for trend showed a significant decline in annual incidence from 2001 to 2008, for both CD (p<0.003) and UC (p<0.001).Table: Table. Annual incidence rate (IR) for Crohn's disease and ulcerative colitis, Québec 2001-2008†Conclusion: During 2001-2008, the incidence for both CD and UC declined.