Relationship between smoking and colonic involvement in inflammatory boweldisease

The effects of smoking on the onset and clinical course of inflammatory bow el disease (IBD) have been widely debated. Although smoking appears to have a clearly unfavorable effect on the course in Crohn's Disease (CD), the re lationship between smoking and localization of the disease is less clear. AIM: to evaluate, in our group of patients, the relationship between smokin g and the development of ulcerative colitis (UC) or CD, and between smoking and the localization of CD in the large bowel or in other sites. PATIENTS AND METHODS: the smoking habits of 171 patients at the time of dia gnosis were assessed with a questionnaire. Subjects were classified into th ree subgroups as smokers, nonsmokers and ex-smokers. Current smokers were g rouped according to their level of consumption as those who smoked fewer th an or more than 10 cigarettes per day. A total of 161 patients were studied (UC n = 69, CD n = 92). Patients with CD were divided into those with colo nic disease and those with no colonic involvement. We evaluated the relatio nship between smoking and the form of IBD, localization (colonic or noncolo nic) and the presence of perianal disease (PAD) in CD. The results were ana lyzed with the chi-squared test. RESULTS: smoking was more frequent in patients with CD than in those with U C (72.8% vs 31.9%). Among patients with CD, more patients without colonic i nvolvement were smokers (84.6% vs 64.2%). However, among patients with CD i nvolving the colon, smoking was significantly more common (64.2%) than amon g patients who had UC (31.9%). CONCLUSIONS: our findings confirm a relationship between smoking and CD. Sm oking seems to be associated with some degree of protection of the colonic mucosa, especially in heavy smokers.