Smoking and ulcerative colitis: a community study.

Smoking habits of patients with ulcerative colitis, diagnosed in the City of Cardiff between the 1st of January 1978 and the 31st of December 1987 were examined. There was a significant deficit of current smokers, an excess of life-long non-smokers and ex-smokers compared with the general population. Men who had previously smoked presented with colitis later than life long non-smokers (mean age difference 16.1 years). The proportion of ex-smokers in this group of patients with colitis was more than twice that expected in the general population. The interval between cessation of smoking and subsequent onset of colitis in ex-smokers was relatively short and in more than half of them occurred within 8 years. There was no significant difference in the frequency of colectomy or the extent of disease among smokers, ex-smokers or life-long non-smokers with ulcerative colitis.