title: A population-based case control study of potential risk factors for IBD.
abstract: BACKGROUND
  We aimed to pursue potential etiological clues to Crohn's disease (CD) and ulcerative colitis (UC) through a population-based case control survey study.
  
  
  METHODS
  Cases with CD (n = 364) and UC (n = 217), ages 18-50 yr were drawn from the population-based University of Manitoba IBD Research Registry. Potential control subjects were drawn from the population-based Manitoba Health Registry by age, gender, and geographic residence matching to the cases (n = 433). Subjects were administered a multiitem questionnaire.
  
  
  RESULTS
  By univariate analysis, some of the variables predictive of CD included lower likelihood of living on a farm, of having drunk unpasteurized milk or having eaten pork, and UC patients were less likely to have drunk unpasteurized milk and to have eaten pork. On multivariate analysis, variables significantly associated with CD were being Jewish (OR = 4.32, 95% CI 1.10-16.9), having a first degree relative with IBD (OR = 3.07, 95% CI 1.73-5.46), ever having smoked (OR = 1.54, 95% CI, 1.06-2.25), living longer with a smoker (OR = 1.03, 95% CI, 1.01-1.04). Being a first generation Canadian (OR = 0.33, 95% CI, 0.17-0.62), having pet cats before age 5 (OR = 0.66, 95% CI, 0.46-0.96) and having larger families (OR = 0.87, 95% CI, 0.79-0.96) were protective against CD. For UC being Jewish (OR = 7.46, 95% CI, 2.33-23.89), having a relative with IBD (OR = 2.23, 95% CI, 1.27-3.9), and ever smoking (OR = 1.62, 95% CI, 1.14-2.32) were predictive.
  
  
  CONCLUSIONS
  This study reinforced the increased risk associated with family history, being Jewish, and smoking history, however, a number of significant associations with CD and UC on univariate and multivariate analysis may support the "hygiene hypothesis" and warrant further exploration in prospective studies.
authors.affiliation: University of Manitoba Inflammatory Bowel Disease Clinical and Research Centre, Winnipeg, Manitoba, Canada.
authors.forename: Charles N
authors.initials: CN
authors.lastname: Bernstein
authors.forename: Patricia
authors.initials: P
authors.lastname: Rawsthorne
authors.forename: Mary
authors.initials: M
authors.lastname: Cheang
authors.forename: James F
authors.initials: JF
authors.lastname: Blanchard
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D000829:Animals, Domestic; D002170:Canada; D016022:Case-Control Studies; D002415:Cats; D002675:Child, Preschool; D003093:Colitis, Ulcerative / Q000209:etiology*; D003424:Crohn Disease / Q000209:etiology*; D004032:Diet; D005191:Family Characteristics; D005260:Female; D006801:Humans; D007585:Jews; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D012111:Residence Characteristics; D012307:Risk Factors; D012907:Smoking; D011795:Surveys and Questionnaires