title: A prospective study of cigarette smoking and the risk of inflammatory bowel disease in women.
abstract: OBJECTIVE
  Long-term data on the influence of cigarette smoking, especially cessation, on the risk of Crohn's disease (CD) and ulcerative colitis (UC) are limited.
  
  
  METHODS
  We conducted a prospective study of 229,111 women in the Nurses' Health Study (NHS) and Nurses' Health Study II (NHS II). Biennially, we collected updated data on cigarette smoking, other risk factors, and diagnoses of CD or UC confirmed by medical record review.
  
  
  RESULTS
  Over 32 years in NHS and 18 years in NHS II, we documented 336 incident cases of CD and 400 incident cases of UC. Compared with never smokers, the multivariate hazard ratio (HR) of CD was 1.90 (95% confidence interval (CI), 1.42-2.53) among current smokers and 1.35 (95% CI, 1.05-1.73) among former smokers. Increasing pack-years was associated with increasing risk of CD (Ptrend < 0.0001), whereas smoking cessation was associated with an attenuation of risk. By contrast, the multivariate HR of UC was 0.86 (95% CI, 0.61-1.20) among current smokers and 1.56 (95% CI, 1.26-1.93) among former smokers. The risk of UC was significantly increased within 2-5 years of smoking cessation (HR, 3.06; 95% CI, 2.00-4.67) and remained persistently elevated over 20 years.
  
  
  CONCLUSIONS
  Current smoking is associated with an increased risk of CD, but not UC. By contrast, former smoking is associated with an increased risk of UC, with risk persisting over two decades after cessation.
authors: Division of Gastroenterology and Nutrition, Children's Hospital Boston, Boston, Massachusetts 02115, USA. leslie.higuchi@childrens.harvard.edu
authors: Leslie M
authors: LM
authors: Higuchi
authors: Hamed
authors: H
authors: Khalili
authors: Andrew T
authors: AT
authors: Chan
authors: James M
authors: JM
authors: Richter
authors: Athos
authors: A
authors: Bousvaros
authors: Charles S
authors: CS
authors: Fuchs
mesh_terms: D000328:Adult; D003093:Colitis, Ulcerative / Q000453:epidemiology* / Q000209:etiology; D003424:Crohn Disease / Q000453:epidemiology* / Q000209:etiology; D005260:Female; D006306:Health Surveys; D006801:Humans; D015994:Incidence; D008137:Longitudinal Studies; D008875:Middle Aged; D011446:Prospective Studies; D012306:Risk; D012907:Smoking / Q000009:adverse effects*; D016540:Smoking Cessation; D011795:Surveys and Questionnaires; D014930:Women