Introduction Smoking is a risk factor for developing Crohn's disease (CD) and worsens its outcome. Conversely, the onset of ulcerative colitis (UC) may be triggered by smoking cessation and smoking may be beneficial. Successful smoking cessation is inversely related to nicotine dependence. We aimed to assess smoking dependence in inflammatory bowel disease (IBD) patients compared to healthy and disease-matched controls and individuals’ smoking knowledge.

Methods 255 IBD patients (182CD:73UC) completed a questionnaire on smoking habits and its effect on IBD. Smokers were assessed for dependence using the Fagerstrom Test for Nicotine Dependence (FTND) score (1) (0–2 very low, 3–4 low,5 medium, 6–7 high, 8–10 very high dependence) compared to age, sex and ethnicity-matched healthy (5 subjects for each case) and asthma controls attending a smoking cessation clinic. The median (range) age was 38 (18–90) years and disease duration 9 (1–54) years for the IBD patients. Differences were sought using χ² test in categorical and Wilcoxon signed rank or Mann–Whitney U test in continuous data.

Results 35/182 (19%) CD and 9/73 (12%) UC were current smokers. In CD, the median (range) FTND score was 3 (0–8) compared to 7 (2–10) in healthy (p<0.001) and 6 (2–9) in asthma controls (p<0.001). Only six of the 35 (17%) CD patients were highly dependent (FTND score ≥ 6). Smoking dependence was unrelated to ethnicity. Similarly, in UC the FTND score was 1 (0–4), lower than healthy 6 (2–10) and asthma controls 7 (4–10) (p<0.004 for both groups). There was no difference in dependence between CD and UC patients. 88% CD smokers were interested in stopping smoking and 33% would consider attending a smoking cessation clinic. Patients with CD were better informed about the effects of smoking on their own disease compared to UC patients: 66/112 (59%) of CD patients knew that smoking worsens CD, whereas only 6/73 (8%) UC patients knew of the beneficial effects of smoking on their disease (p=0.0001). Knowledge was unrelated to smoking status.

Conclusion A smaller proportion of our CD patients are smokers than has been reported in previous series (26–61%). Most patients with CD, regardless of their smoking status, recognise the detrimental effects of smoking on their disease. Nicotine dependence in IBD patients is lower than in smokers’ clinic clients and comparable to the general population. The level of interest in smoking cessation is high. Their low nicotine dependence suggests that most IBD patients could be weaned off smoking successfully in the IBD clinic and may not need referral to a smoking cessation clinic.