title: Prevalence of Inflammatory Bowel Disease in the Canton of Vaud (Switzerland): A population-based cohort study.
abstract: OBJECTIVE
  Because of the changing epidemiology of Inflammatory Bowel Diseases (IBD), we set out to characterize the population-based prevalence of Crohn's Disease (CD) and Ulcerative Colitis (UC) in a defined population of Switzerland.
  
  
  METHODS
  Adult IBD patients were identified by a cross-matched review of histological, hospital and gastroenterologist files throughout a geographical defined population (Canton of Vaud). Demographic factors statistically significantly associated with prevalence were evaluated using a stepwise Poisson regression analysis. Results were compared to IBD prevalence rates in other population-based studies and time trends were performed, based on a systematic literature review.
  
  
  RESULTS
  Age and sex-adjusted prevalence rates were 205.7 IBD (100.7 CD and 105.0 UC) cases per 10(5) inhabitants. Among 1016 IBD patients (519 CD and 497 UC), females outnumbered males in CD (p<0.001), but males were more represented in elderly UC patients (p=0.008). Thus, being a male was statistically associated with UC (Relative Risk (RR) 1.25; p=0.013), whereas being a female was associated with CD (RR 1.27; p=0.007). Living in an urban zone was associated with both CD and UC (RR 1.49; p<0.001, 1.63; p<0.001, respectively). From 1960 to 2005, increases in UC and CD prevalences of 2.4% (95%CI, 2.1%-2.8%; p<0.001) and 3.6% (95%CI, 3.1%-4.1%; p<0.001) per annum were found in industrialised countries.
  
  
  CONCLUSIONS
  Extrapolating our data to all of Switzerland yields an estimate of 12,000 IBD cases for the country, or 1 in 500 inhabitants. Our study gives support to an increase in IBD prevalence in Europe.
authors.affiliation: Division of Gastroenterology and Hepatology, Centre Hospitalier Universitaire Vaudois, Rue du Bugnon 46, CH-1011 Lausanne, Switzerland.
authors.forename: Pascal
authors.initials: P
authors.lastname: Juillerat
authors.forename: Valérie
authors.initials: V
authors.lastname: Pittet
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Bulliard
authors.forename: Idris
authors.initials: I
authors.lastname: Guessous
authors.forename: Anca Teodora
authors.initials: AT
authors.lastname: Antonino
authors.forename: Christian
authors.initials: C
authors.lastname: Mottet
authors.forename: Christian
authors.initials: C
authors.lastname: Felley
authors.forename: John-Paul
authors.initials: JP
authors.lastname: Vader
authors.forename: Pierre
authors.initials: P
authors.lastname: Michetti