Crohn's disease and smoking: is it ever too late to quit?

J Crohns Colitis. 2013 Dec;7(12):e665-71. doi: 10.1016/j.crohns.2013.05.007. Epub 2013 Jun 20.


Background: Smoking increases CD risk. The aim was to determine if smoking cessation at, prior to, or following, CD diagnosis affects medication use, disease phenotypic progression and/or surgery.

Methods: Data on CD patients with disease for ≥5 yrs were collected retrospectively including the Montreal classification, smoking history, CD-related abdominal surgeries, family history, medication use and disease behaviour at diagnosis and the time when the disease behaviour changed.

Results: 1115 patients were included across six sites (mean follow-up-16.6 yrs). More non-smokers were male (p=0.047) with A1 (p<0.0001), L4 (p=0.028) and perianal (p=0.03) disease. Non-smokers more frequently received anti-TNF agents (p=0.049). (p=0.017: OR 2.5 95%CI 1.18-5.16) and those who ceased smoking prior to diagnosis (p=0.045: OR 2.3 95%CI 1.02-5.21) progressed to complicated (B2/B3) disease as compared to those quitting at diagnosis. Patients with uncomplicated terminal ileal disease at diagnosis more frequently developed B2/B3 disease than isolated colonic CD (p<0.0001). B2/B3 disease was more frequent with perianal disease (p<0.0001) and if i.v. steroids (p=0.004) or immunosuppressants (p<0.0001) were used. 49.3% (558/1115) of patients required at least one intestinal surgery. More smokers had a 2nd surgical resection than patients who quit at, or before, the 1st resection and non-smokers (p=0.044: HR=1.39 95%CI 1.01-1.91). Patients smoking >3 cigarettes/day had an increased risk of developing B2/B3 disease (p=0.012: OR 3.8 95%CI 1.27-11.17).

Conclusion: Progression to B2/B3 disease and surgery is reduced by smoking cessation. All CD patients regardless of when they were diagnosed, or how many surgeries, should be strongly encouraged to cease smoking.

Keywords: Crohn's disease; Disease progression; Smoking; Surgery.

MeSH terms

  • Adolescent
  • Adult
  • Anus Diseases / pathology
  • Colitis / pathology*
  • Crohn Disease / pathology
  • Crohn Disease / therapy*
  • Disease Progression*
  • Female
  • Follow-Up Studies
  • Humans
  • Ileitis / pathology*
  • Immunosuppressive Agents / therapeutic use
  • Male
  • Reoperation
  • Retrospective Studies
  • Severity of Illness Index
  • Smoking / adverse effects*
  • Smoking Cessation*
  • Steroids / therapeutic use
  • Tumor Necrosis Factor-alpha / antagonists & inhibitors
  • Young Adult


  • Immunosuppressive Agents
  • Steroids
  • Tumor Necrosis Factor-alpha