Protective effect of appendectomy on the development of ulcerative colitis. A case-control study

Aims - To examine by a case-control study the relationship between appendec tomy and subsequent ulcerative colitis development in a French population. Methods-A total of 150 patients with ulcerative colitis were matched for ag e (+/- 5years) and sex, with 150 controls recruited in a preventive medicin e center. The following data were collected from medical records and by sta ndardised questionnaire in consultation or by phone: appendectomy and tonsi llectomy before the onset of ulcerative colitis, smoking habits and area of residence. Results-The rate of previous appendectomy in patients with ulcerative colit is was 8% (12/150) compared with 30.6% (46/150) in the control group (P = 0 .001). There was no significant association between ulcerative colitis and tonsillectomy (25.3 and 27.3% in the control and the ulcerative colitis gro ups, respectively). Smoking was more frequent in the control group (36%) th an in the ulcerative colitis group (25.3%) but the difference was not signi ficant (P = 0.07). In multivariate analysis, the risk of developing ulcerat ive colitis was significantly lower after previous appendectomy (odds ratio = 0.26; 95% confidence interval: 0.13-0.55; P = 7 x 10(-4)). Conclusion - Our study confirms the inverse association between appendectom y and subsequent ulcerative colitis, in a French population, after adjustin g on smoking.