APPENDECTOMY AND THE RISK OF DEVELOPING ULCERATIVE-COLITIS OR CROHNS-DISEASE - RESULTS OF A LARGE CASE-CONTROL STUDY

Background & Aims: Appendectomy has been pointed out as a protective f actor for ulcerative colitis (UC), The aim of this study was to elucid ate the role of appendectomy in inflammatory bower disease (IBD). Meth ods: Prevalent as well as incident cases with IBD were studied separat ely using a pairwise age- and sex-matched case-control study design. R esults: In 232 prevalent UC cases, the risk of developing UC was signi ficantly lower after previous appendectomy (odds ratio [OR], 0.36; 95% confidence interval [CI], 0.15-0.80); subgroup analysis found a prote ctive effect only in pancolitis (OR, 0.2; 95% CI, 0.02-0.7), In 208 pa tients with Crohn's disease (CD), the OR was not significantly increas ed but a positive association with appendectomy was observed in ileoce cal disease. A significant larger proportion of appendectomies was per formed close to the time of diagnosis, Smoking was not a confounding f actor. No statistically significant associations were observed in inci dent IBD patients, Prevalent and incident patients taken together resu lted in ORs of 0.44 (95% CI, 0.24-0.78) in UC and 1.65 (95% CI, 0.96-2 .91) in CD. Conclusions: An overall protective role of appendectomy fo r UC was observed, The observations in CD suggest that appendectomy in some cases was a result of still undiagnosed CD.