Lack of association between smoking and Crohn's disease but the usual association with ulcerative colitis in Jewish patients in Israel: A multicenterstudy

OBJECTIVE: The association between smoking and inflammatory bowel disease ( IBD) is well established, but data in Jewish patients in Israel were discre pant. The aim of this study was to examine the smoking habits of Jewish IBD patients in Israel in a large scale, multicenter study. METHODS: Patients with established IBD aged 18-70 yr were interviewed in re lation to smoking and other habits. Two controls (one clinic and one neighb orhood control matched by age, sex, community group, and education) were so ught for each subject. RESULTS: A total of 534 patients (273 ulcerative colitis [UC], and 261 Croh n's disease [CD]), along with 478 clinic controls and 430 neighborhood cont rols, were interviewed. There was no significant difference in the smoking habits between CD patients and their controls. Of patients with CD, 24.5% W ere current smokers, as compared to 19.9% Of clinic controls and 25.2% of n eighborhood controls (NS). The odds ratio for CD in current smokers was 1.3 0 (95% confidence interval 0.85-1.99) versus clinic controls, and 0.96 (0.6 3-1.46) versus neighborhood controls. There were also no significant differ ences in the proportion of ex-smokers between the groups. Only 12.9% of UC patients were current smokers versus 21.9. % Clinic controls, and 26.4% com munity controls (p < 0.005). The proportions of ex-smokers were higher in U C patients 29.7% versus 25.9%, and 19.5% in their respective controls (p < 0.001 vs community controls). No significant differences were found in the proportions of never-smokers between IBD patients and controls. All the abo ve trends were similar in four different parts of the country. The proporti on of current smokers in UC decreased with the extent of disease (19.7% in proctitis, 13.6% in left-sided, and 4.5% in total colitis) (p < 0.05). Pati ents with UC were more likely to be light smokers(1-10 cigarettes/day), whe reas patients with CD were more likely to be moderate smokers (11-20 cigare ttes/day) in comparison to their controls. CONCLUSIONS: The lack of association between smoking and CD has now been es tablished in Jewish patients in Israel. The association was found in UC. Th e stronger genetic tendency in CD may contribute to this discrepancy. (C) 2 000 by Am. Cell. of Gastroenterology.