title: The prevalence of extraintestinal diseases in inflammatory bowel disease: a population-based study.
abstract: OBJECTIVE
  The aim of this study was to determine the prevalence of the major extraintestinal manifestations of inflammatory bowel disease (IBD) and their relation to disease diagnosis and gender.
  
  
  METHODS
  We used the population-based University of Manitoba IBD Database, which includes longitudinal files on all subjects of all health system contacts identified by International Classification of Diseases, 9th Revision, Clinical Modification codes for visit diagnosis. We extracted a cohort from our database, which included subjects with a known diagnosis of IBD for at least 10 yr. We then determined how many contacts each subject had for each of the following extraintestinal IBD-associated immune diseases: primary sclerosing cholangitis, ankylosing spondylitis, iritis/uveitis, pyoderma gangrenosum, and erythema nodosum. We calculated the prevalence of the extraintestinal diseases using an administrative definition of having at least five health system contacts for the diagnosis in question. This administrative definition has previously been validated in Crohn's disease and ulcerative colitis (UC).
  
  
  RESULTS
  A total of 6.2% of patients with IBD had one of six major extraintestinal diseases studied in this report. Only 0.3% of patients had multiple extraintestinal diseases. Iritis/uveitis was the most common extraintestinal disease of all assessed (2.2% of women and 1.1% of men). Iritis/uveitis was more common among women, particularly those with UC (3.8%). Primary sclerosing cholangitis was most common among men with UC (3%). Ankylosing spondylitis was more common among men, and the highest rate was seen among men with Crohn's disease (2.7%). Pyoderma gangrenosum was more common in Crohn's (1.2%) with no gender predilection. Erythema nodosum was similarly present in Crohn's and UC but was more common among women (1.9%).
  
  
  CONCLUSIONS
  The associations of immune mediated diseases in extraintestinal sites may help us to further our understanding of IBD pathogenesis, and it may help us in developing a paradigm of disease subsets.
authors.affiliation: Department of Internal Medicine, University of Manitoba, Winnipeg, Canada.
authors.forename: C N
authors.initials: CN
authors.lastname: Bernstein
authors.forename: J F
authors.initials: JF
authors.lastname: Blanchard
authors.forename: P
authors.initials: P
authors.lastname: Rawsthorne
authors.forename: N
authors.initials: N
authors.lastname: Yu
mesh_terms: D000328:Adult; D015209:Cholangitis, Sclerosing / Q000453:epidemiology / Q000209:etiology; D004893:Erythema Nodosum / Q000453:epidemiology / Q000209:etiology; D005260:Female; D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000150:complications*; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D017511:Pyoderma Gangrenosum / Q000453:epidemiology / Q000209:etiology; D013167:Spondylitis, Ankylosing / Q000453:epidemiology / Q000209:etiology; D014603:Uveal Diseases / Q000453:epidemiology / Q000209:etiology