title: Effects of active and passive smoking on disease course of Crohn's disease and ulcerative colitis.
abstract: BACKGROUND
  Smoking is a remarkable risk factor for inflammatory bowel disease (IBD), aggravating Crohn's disease (CD) while having beneficial effects on ulcerative colitis (UC). We studied the effects of active and passive smoking in Dutch IBD patients.
  
  
  METHODS
  A questionnaire focusing on cigarette smoke exposure was sent to 820 IBD patients. Returned questionnaires were incorporated into a retrospective chart review, containing details about disease behavior and received therapy.
  
  
  RESULTS
  In all, 675 IBD patients (380 [56%] CD and 295 [44%] UC) responded. At diagnosis there were 52% smokers in CD, 41% in the general population, and 28% in UC. The number of present smokers in CD is lower than in the general population (26% versus 35%). No detrimental effects of active smoking on CD were observed, but passive smokers needed immunosuppressants and infliximab more frequently than nonpassive smokers. Active smoking had beneficial effects on UC, indicated by reduced rates of colectomy, primary sclerosing cholangitis, and backwash-ileitis in active smokers compared to never smokers, and higher daily cigarette dose correlated with less extensive colitis and a lower need for therapy. Furthermore, smoking cessation after diagnosis was detrimental for UC patients, indicated by increased needs for steroids and hospitalizations for patients that stopped smoking after compared to before the diagnosis.
  
  
  CONCLUSIONS
  Active smoking is a risk factor for CD, but does not affect the outcome; passive smoking is detrimental for the outcome of CD patients. In UC, active smoking shows dose-dependent beneficial effects. Our data suggest that passive smoking is a novel risk factor for CD.
authors.affiliation: Department of Gastroenterology and Hepatology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands. f.van.der.heide@int.umcg.nl
authors.forename: Frans
authors.initials: F
authors.lastname: van der Heide
authors.forename: Arie
authors.initials: A
authors.lastname: Dijkstra
authors.forename: Rinse K
authors.initials: RK
authors.lastname: Weersma
authors.forename: Frans A
authors.initials: FA
authors.lastname: Albersnagel
authors.forename: Elise M J
authors.initials: EM
authors.lastname: van der Logt
authors.forename: Klaas Nico
authors.initials: KN
authors.lastname: Faber
authors.forename: Wim J
authors.initials: WJ
authors.lastname: Sluiter
authors.forename: Jan H
authors.initials: JH
authors.lastname: Kleibeuker
authors.forename: Gerard
authors.initials: G
authors.lastname: Dijkstra
mesh_terms: D000328:Adult; D003093:Colitis, Ulcerative / Q000503:physiopathology*; D003424:Crohn Disease / Q000503:physiopathology*; D005260:Female; D005500:Follow-Up Studies; D006760:Hospitalization; D006801:Humans; D008297:Male; D011379:Prognosis; D012189:Retrospective Studies; D012307:Risk Factors; D012907:Smoking / Q000503:physiopathology*; D011795:Surveys and Questionnaires; D014028:Tobacco Smoke Pollution; D055815:Young Adult
chemical_list: D014028:Tobacco Smoke Pollution