title: Appendectomy and the risk of developing ulcerative colitis or Crohn's disease: results of a large case-control study. South Limburg Inflammatory Bowel Disease Study Group.
abstract: OBJECTIVE
  Appendectomy has been pointed out as a protective factor for ulcerative colitis (UC). The aim of this study was to elucidate the role of appendectomy in inflammatory bowel disease (IBD).
  
  
  METHODS
  Prevalent as well as incident cases with IBD were studied separately using a pairwise age- and sex-matched case-control study design.
  
  
  RESULTS
  In 232 prevalent UC cases, the risk of developing UC was significantly lower after previous appendectomy (odds ratio [OR], 0.36; 95% confidence interval [CI], 0.15-0.80); subgroup analysis found a protective effect only in pancolitis (OR, 0.2; 95% CI, 0.02-0.7). In 208 patients with Crohn's disease (CD), the OR was not significantly increased but a positive association with appendectomy was observed in ileocecal disease. A significant larger proportion of appendectomies was performed close to the time of diagnosis. Smoking was not a confounding factor. No statistically significant associations were observed in incident IBD patients. Prevalent and incident patients taken together resulted 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 for UC was observed. The observations in CD suggest that appendectomy in some cases was a result of still undiagnosed CD.
authors.affiliation: Department of Gastroenterology, University Hospital Maastricht, The Netherlands.
authors.forename: M G
authors.initials: MG
authors.lastname: Russel
authors.forename: E
authors.initials: E
authors.lastname: Dorant
authors.forename: R J
authors.initials: RJ
authors.lastname: Brummer
authors.forename: M A
authors.initials: MA
authors.lastname: van de Kruijs
authors.forename: J W
authors.initials: JW
authors.lastname: Muris
authors.forename: J M
authors.initials: JM
authors.lastname: Bergers
authors.forename: J
authors.initials: J
authors.lastname: Goedhard
authors.forename: R W
authors.initials: RW
authors.lastname: Stockbrügger
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001062:Appendectomy / Q000592:standards* / Q000706:statistics & numerical data; D016022:Case-Control Studies; D003093:Colitis, Ulcerative / Q000175:diagnosis / Q000453:epidemiology* / Q000517:prevention & control; D003424:Crohn Disease / Q000175:diagnosis / Q000453:epidemiology* / Q000517:prevention & control; D005260:Female; D006801:Humans; D015994:Incidence; D015212:Inflammatory Bowel Diseases / Q000175:diagnosis / Q000453:epidemiology / Q000517:prevention & control; D008297:Male; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D015995:Prevalence; D012307:Risk Factors