title: Appendectomy and subsequent risk of inflammatory bowel diseases.
abstract: BACKGROUND
  Case-control studies have reported an inverse relationship between appendectomy and the risk of ulcerative colitis, but the association has not been confirmed in prospective studies.
  
  
  METHODS
  Using national hospital discharge registry data in Denmark, the authors followed up 154,434 patients who underwent appendectomy during the period 1977 to 1989 to investigate whether they had subsequent hospitalizations for ulcerative colitis and Crohn's disease. Ratios of observed-to-expected first hospitalizations for inflammatory bowel diseases served as measures of the relative risk (RR).
  
  
  RESULTS
  Hospitalization for ulcerative colitis occurred in 84 patients who had appendectomies versus 97.0 expected (RR = 0.87; 95% CI, 0.69-1.07). RRs were not significantly reduced in subgroups defined by sex, age, time since appendectomy, calendar period, or cause of appendectomy. Hospitalization for Crohn's disease occurred in excess (RR = 2.88; 95% CI, 2.45-3.39; n = 150), notably in the first year after appendectomy (RR = 10.83; 95% CI, 8.49-13.62; n = 73); but after 5 years, the RR was not significantly elevated.
  
  
  CONCLUSIONS
  This large population-based cohort study failed to support a significant inverse association between appendectomy and ulcerative colitis risk in the first decade after the operation. The excess of Crohn's disease shortly after appendectomy most likely reflects differential diagnostic problems in patients newly presenting with abdominal pain.
authors: Department of Epidemiology Research, Danish Epidemiology Science Center, Statens Serum Institut, Copenhagen, Denmark.
authors: M
authors: M
authors: Frisch
authors: C
authors: C
authors: Johansen
authors: L
authors: L
authors: Mellemkjaer
authors: E A
authors: EA
authors: Engels
authors: G
authors: G
authors: Gridley
authors: R J
authors: RJ
authors: Biggar
authors: J H
authors: JH
authors: Olsen
mesh_terms: D000328:Adult; D001062:Appendectomy; D015331:Cohort Studies; D003093:Colitis, Ulcerative / Q000209:etiology* / Q000628:therapy; D003424:Crohn Disease / Q000209:etiology* / Q000628:therapy; D005260:Female; D006760:Hospitalization; D006801:Humans; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period; D011446:Prospective Studies; D012307:Risk Factors