RISK OF PRIMARY SCLEROSING CHOLANGITIS IS ASSOCIATED WITH NONSMOKING BEHAVIOR

Background & Aims: Seventy percent of patients with primary sclerosing cholangitis (PSC) have concomitant ulcerative colitis. Smoking and pr evious appendectomy may protect against ulcerative colitis. The aim of this study was to examine these factors in patients with PSC. Methods : Fifty-nine patients with PSC, 130 patients with ulcerative colitis a nd normal liver biochemistry, and 197 control subjects were interviewe d about smoking behavior and history of appendectomy. Results: There w ere less current smokers in the PSC and ulcerative colitis groups than in the control group (19%, 12%, and 38%, respectively). The resulting odds ratio for current smoking was 0.37 (95% confidence interval, 0.1 8-0.76) in the PSC group and 0.23 (95% confidence interval, 0.13-0.41) in the ulcerative colitis group. Percentage of persons who ever smoke d was also significantly less in the PSC group (41% vs. 56% in the con trol group). Frequency of previous appendectomy in the PSC and ulcerat ive colitis groups was not significantly different from that of contro ls (19%, 9%, and 14%, respectively). Conclusions: Smoking but not prev ious appendectomy is associated with decreased risk of PSC.