title: The effect of appendectomy on the course of ulcerative colitis: a systematic review.
abstract: OBJECTIVE
  Previous studies have shown significantly lower appendectomy rates in ulcerative colitis (UC) patients compared with healthy controls. Evidence indicating that the appendix has an immunomodulatory role in UC has been accumulating. To examine the latest evidence on the effect of appendectomy on the disease course of UC.
  
  
  METHODS
  PubMed, The Cochrane Library and EMBASE were searched. Primary end-points were number of relapses, use of steroids, number of hospital admissions and number of colectomies.
  
  
  RESULTS
  The search resulted in six observational studies (five case-control studies and one cohort study) totalling 2532 patients. Owing to clinical heterogeneity, no meta-analysis could be conducted. One study found lower relapse rates in patients appendectomized before the onset of UC [absolute risk reduction (ARR)=21.5%; 95% CI: 1.71-45.92%]. Another two studies found a reduced requirement for immunosuppression in appendectomized patients (ARR=20.2%; 95% CI: 9.67-30.46% in the first study and ARR=21.4%; 95% CI: 10.32-32.97% in the second study). In addition, one study found lower colectomy rates in nonappendectomized patients (ARR=8.7%; 95% CI: 1.29-18.66%) and two studies found lower colectomy rates in appendectomized patients (ARR=21.4%; 95% CI: 13.17-28.79% in the first study and ARR=18.7%; 95% CI: 7.50-29.97% in the second study).
  
  
  CONCLUSIONS
  There are limited and conflicting data available regarding the effect of appendectomy on the disease course of UC. Most studies suggest a beneficial effect and the minority find no, or a negative, effect.
authors.affiliation: Department of Surgery, Academic Medical Center, Amsterdam, The Netherlands.
authors.forename: T J
authors.initials: TJ
authors.lastname: Gardenbroek
authors.forename: E J
authors.initials: EJ
authors.lastname: Eshuis
authors.forename: C I J
authors.initials: CI
authors.lastname: Ponsioen
authors.forename: D T
authors.initials: DT
authors.lastname: Ubbink
authors.forename: G R A M
authors.initials: GR
authors.lastname: D'Haens
authors.forename: W A
authors.initials: WA
authors.lastname: Bemelman
mesh_terms: D001062:Appendectomy; D003082:Colectomy; D003093:Colitis, Ulcerative / Q000209:etiology* / Q000601:surgery; D018450:Disease Progression; D006801:Humans; D012008:Recurrence