Appendectomy protects against the development of ulcerative colitis and reduces its recurrence: Results of a multicenter case-controlled study in Japan

OBJECTIVES: Studies in the US and Europe have shown that appendectomy may p revent the development of ulcerative colitis, but no detailed study has bee n conducted in Japan, where ulcerative colitis is uncommon and the populati on is racially homogeneous. In addition, there has been no detailed analysi s of the relationship between appendectomy and the clinical course of ulcer ative colitis. In this multicenter clinical study, we evaluated the effects of appendectomy on ulcerative colitis in Japan. METHODS: A case-control study was undertaken in seven medical institutions comparing the incidence of appendectomy and tonsillectomy in 325 patients w ith ulcerative colitis and 325 controls matched for age (10-yr intervals) a nd sex. Disease duration, extent, and prognosis were determined in 21 patie nts with ulcerative colitis who underwent appendectomies and 304 patients w ith ulcerative colitis who did not undergo appendectomies. RESULTS: Appendectomy was performed in a significantly lower percentage of patients in the ulcerative colitis group (21/325, 6.5%) than in the control group (53/325, 16.3%) (p < 0.001) (odds ratios = 0.355, 95% CI = 0.208-0.6 03). In contrast, no significant difference was observed between the groups with respect to tonsillectomy. The mean age (25.7 +/- 10.9 yr) of patients with ulcerative colitis at the time of appendectomy was significantly high er than the mean age (20.1 +/- 8.7 yr) of patients in the control group at the time of appendectomy (p < 0.05). The incidence of proctitis was higher in the appendectomy group than in the group that did not undergo appendecto mies (38.1% vs 18.1%). In addition, the recurrence rates were significantly lower in the appendectomy group than in the group that did not undergo app endectomies (57.1% vs 78.6%, p < 0.05), although both groups were similar i n composition as to sex, age, duration of disease, smoking status, and prev ious medical treatment. CONCLUSIONS: Our results indicate that appendectomy has a negative associat ion with and perhaps a preventive effect on the development of ulcerative c olitis in the Japanese population. Furthermore. appendectomy also appears t o reduce the extent and recurrence of ulcerative colitis. (Am J Gastroenter ol 2001;96:1123-1126. (C) 2001 by Am. Coll. of Gastroenterology).