Background and aims: The aim of this study was to examine in parallel the effect of smoking on ulcerative colitis and Crohn's colitis and assess the effect of gender on the response of colitis to smoking.
Methods: Medical charts of 1784 adult consecutive patients (978 patients, ulcerative colitis; 118 patients, indeterminate colitis; and 688 patients, Crohn's colitis), whose smoking habits were specified by direct interview, were reviewed.
Results: The proportion of ever smokers was 42% in ulcerative colitis, 43% in indeterminate colitis, and 61% in Crohn's colitis. Smoking cessation preceded the onset of colitis in 279 patients with ulcerative colitis or indeterminate colitis (61%) and only 52 patients (12%) with Crohn's colitis. In ulcerative colitis and indeterminate colitis, current smoking delayed mean age at disease onset in men (from 32 to 41 yr; P < 0.001), but not women (from 33 to 33 yr), and decreased the need for immunosuppressants in men (10-yr cumulative risk, 26% +/- 4% in nonsmokers vs. 8% +/- 4% in smokers; P < 0.01), but not significantly in women. Conversely, in Crohn's colitis, current smoking hastened disease onset in women (from 35 to 29 yr; P < 0.001), but not men (from 32 to 31 yr), and increased the need for immunosuppressants in women (10-yr cumulative risk, 48% +/- 5% in nonsmokers vs. 58% +/- 4% in smokers; P < 0.01), but not men.
Conclusions: The dual effects of smoking in colitis, beneficial in ulcerative colitis and harmful in Crohn's colitis, are modulated importantly by gender, with women having more disadvantage than men.