title: Primary sclerosing cholangitis is associated with nonsmoking: a case-control study.
abstract: OBJECTIVE
  Cigarette smoking is thought to protect against the development of ulcerative colitis. The relationship between a related disease, primary sclerosing cholangitis, and smoking is unknown. The aim of this study was to determine if the relationship between smoking and sclerosing cholangitis is similar to that found between smoking and ulcerative colitis.
  
  
  METHODS
  A stratified sample of 184 patients with primary sclerosing cholangitis and age- and sex-matched institutional control subjects were identified. Smoking information was obtained from a medical questionnaire completed at the time of visit.
  
  
  RESULTS
  Eighty-one percent of the patients had associated inflammatory bowel disease. Only 4.9% of them were current smokers compared with 26.1% of the controls; 69.6% of the patients had never smoked vs. 46.7% of the controls. The estimated odds of having primary sclerosing cholangitis in current smokers compared with never-smokers was 0.13. The odds of having disease among former and current users of any tobacco relative to never-users was 0.41 regardless of the presence or absence of inflammatory bowel disease.
  
  
  CONCLUSIONS
  The odds of having primary sclerosing cholangitis was significantly decreased among current smokers. Concomitant ulcerative colitis does not fully explain the association between nonsmoking and primary sclerosing cholangitis. Smoking may exert its protective effect in a systemic, rather than colonic, manner.
authors.affiliation: Inflammatory Bowel Disease Clinic, Division of Gastroenterology and Internal Medicine, Rochester, Minnesota, USA.
authors.forename: E V
authors.initials: EV
authors.lastname: Loftus
authors.forename: W J
authors.initials: WJ
authors.lastname: Sandborn
authors.forename: W J
authors.initials: WJ
authors.lastname: Tremaine
authors.forename: D W
authors.initials: DW
authors.lastname: Mahoney
authors.forename: A R
authors.initials: AR
authors.lastname: Zinsmeister
authors.forename: K P
authors.initials: KP
authors.lastname: Offord
authors.forename: L J
authors.initials: LJ
authors.lastname: Melton
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D015209:Cholangitis, Sclerosing / Q000150:complications / Q000453:epidemiology*; D005260:Female; D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000150:complications / Q000453:epidemiology; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D012907:Smoking / Q000453:epidemiology*