Effects of active and passive smoking on Crohn's disease and ulcerative colitis in a cohort from a regional hospital

Abstract

Smoking is detrimental for Crohn's disease (CD), but beneficial for ulcerative colitis (UC). Earlier, we studied the effects of active and passive smoking in CD and UC patients from a university hospital. This study was conducted to assess the same effects in patients from a regional hospital. A questionnaire focusing on cigarette smoke exposure was sent to 382 patients. Returned questionnaires (84%: 128 CD and 192 UC patients) were incorporated into a retrospective chart review about disease behaviour and received therapy. At diagnosis there were 52% (95% confidence interval: 43-60%) smokers among CD patients, 40% in a control population and 25% (95% confidence interval: 18-31%) among UC patients. There were less former (19 vs. 31%, P = 0.013) and never smokers at diagnosis (30 vs. 44%, P = 0.009) in CD than in UC. No detrimental effects of active or passive smoking on the course of CD were observed. UC patients who continued smoking after diagnosis needed less often two or more hospitalizations than never smokers (5 vs. 25%, P = 0.036). Otherwise no clear beneficial effects of active smoking on UC were observed. Passively smoking UC patients experienced more often extraintestinal manifestations (25 vs. 7%, P = 0.029) than nonpassive smokers. Also in a regional hospital inflammatory bowel disease population smoking is a risk factor to develop CD and protects against developing UC. We found no detrimental effects of smoking on the disease course of CD and no clear beneficial effects on the course of UC.