Active and passive smoking behaviour and cessation plans of patients with Crohn's disease and ulcerative colitis

Smoking is a remarkable risk factor in inflammatory bowel disease (IBD), with negative effects on Crohn's disease (CD) and positive effects on ulcerative colitis (UC). This makes different changes in smoking behaviour after diagnosis between CD and UC likely. Changes in active smoking, cessation plans and passive smoking were studied in IBD patients.

820 IBD patients were sent a questionnaire on active and passive smoking, and cessation plans. A total of 675 (82%) patients (380 CD and 295 UC) responded.

More ever smoking UC patients stopped smoking before diagnosis than CD patients (63% vs 22%; p<0.001), resulting in 30% former smokers at diagnosis in UC and 13% in CD (p<0.001). The smoking cessation rates at and after diagnosis are equal between CD and UC. Half of the CD patients stopped smoking after diagnosis leading to less present smokers in CD than in a control population (26% (95% confidence interval: 21.1%-29.9%) vs 33%). For both CD (22% vs 35%; p=0.044) and UC (24% vs 53%; p=0.024) continuing smokers after diagnosis were less often higher educated than quitters. Cessation plans (89%), passive smoking in childhood and present passive smoking were not different between CD and UC patients.

There are no differences in changes in smoking behaviour at and after diagnosis between CD and UC patients, suggesting a lack of knowledge in these patients about the link between their disease and smoking behaviour. However, CD patients seem less refractory to smoking cessation than the general population. Therefore it is worthwhile putting energy in helping CD patients stop smoking.