[Impact of cigarette smoking on the clinical outcome of Crohn's disease].

Cigarette smoking is a well known independent risk factor for a more severe course of Crohn's disease, but individual factors determining this impact are poorly known and it is not evident if smoking cessation is associated with an improvement in the disease activity. The aim of our study was to assess the factors determining the harmful impact of smoking in individuals with Crohn's disease. A total of 148 consecutive patients with Crohn's disease and Crohn's disease activity index < 200 were enrolled in a prospective 12-18 month study. Patients were classified into three groups as: current smokers, former smokers, and nonsmokers. Body mass index, alcohol consumption, oral contraceptive use and blood lipid levels were also recorded. The main outcome measure was the rate of fare-up. We observed the flare-up developement in 38% current smokers, versus 21% non-smokers and 26% former smokers. The relative risk of flare-up adjusted for confounding factors was 1.37 (1.09 +/- 1.96) in current smokers. Obesity, dyslipidaemia, and alcohol consumption had no significant effect. Current smoking, particularly heavy smoking, significantly increases the risk of flare-up in Crohn's disease patients. Former smokers have a risk similar to that of non-smokers.