Appendectomy is an independent protective factor for ulcerative colitis: results of a multicentre case control study. The Italian Group for the Study of the Colon and Rectum (GISC)

Different exogenous factors are believed to play a role in the pathogenesis of ulcerative colitis. Smoking habits and other risk factors have received much attention. It has recently been reported that appendectomy decreases the risk of ulcerative colitis.

Aim of the study was to further examine the role of appendectomy in ulcerative colitis.

A large multicentre case control study was performed. Cases were all patients with a recent new diagnosis of ulcerative colitis (from 1990 to 1994) at participating centres. One or two controls attending the orthopaedic and surgical units were considered and matched to cases for age (+/- 5 years), sex and year of diagnosis. A total of 536 cases and 755 controls were enrolled. Mean age of cases was 37.9 years (range 2-92). Assessment of exposure was done by examining the clinical records and by interview, if necessary. Smoking habits, alcohol consumption, use of oral contraceptives, type of occupation and area of residence were also recorded. Odds ratio and 95% confidence intervals were calculated by conditional logistic regression analysis.

Forty-one out of the 536 cases (7.6%) and 150 out of the 755 controls (19.9%) had been submitted to appendectomy. A total of 110 out of 536 cases (20.5%) and 135 out of 753 (17.9%) controls had had tonsillectomy. Seven out of 41 cases and 15 out of 755 controls underwent appendectomy for recurrent pain. In all ulcerative colitis patients, appendectomy had been performed before the onset of disease. When data were adjusted for the confounding variables, ulcerative colitis patients were less likely to have had appendectomy compared with controls (odds ratio = 0.3, confidence interval = 0.19-0.48). There was no significant association of ulcerative colitis with tonsillectomy (odds ratio = 1.09, confidence interval = 0.76-1.58). The well recognized inverse association of ulcerative colitis with cigarette smoking was also shown in this study.

The present data emerging from a large multicentre study, confirm that appendectomy has a protective role for the development of ulcerative colitis.