title: Influence of hysterectomy on fistula formation in women with diverticulitis.
abstract: BACKGROUND
  : Diverticulitis is a risk factor for fistula formation but little is known about the influence of hysterectomy in this association. A population-based nationwide matched cohort study was performed to determine the risk of fistula formation in hysterectomized women with, and without, diverticulitis.
  
  
  METHODS
  : Women who had a hysterectomy between 1973 and 2003, and a matched control cohort, were identified from the Swedish Inpatient Register. Incidence of diverticulitis and fistula surgery was determined by cross-linkage to the Register, and risk was estimated using a Cox regression model.
  
  
  RESULTS
  : In a cohort of 168 563 hysterectomized and 614 682 non-hysterectomized women (mean follow-up 11.0 and 11.5 years respectively), there were 14 051 cases of diverticulitis and 851 fistulas. Compared with women who had neither hysterectomy nor diverticulitis, the risk of fistula surgery increased fourfold in hysterectomized women without diverticulitis (hazard ratio (HR) 4.0 (95 per cent confidence interval (c.i.) 3.5 to 4.7)), sevenfold in non-hysterectomized women with diverticulitis (HR 7.6 (4.8 to 12.1)) and 25-fold in hysterectomized women with diverticulitis (HR 25.2 (15.5 to 41.2)).
  
  
  CONCLUSIONS
  : Diverticulitis, and to a lesser extent hysterectomy, is strongly associated with the risk of fistula formation. Hysterectomized women with diverticulitis have the highest risk of developing surgically managed fistula.
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden. daniel.altman@ki.se
authors.forename: D
authors.initials: D
authors.lastname: Altman
authors.forename: C
authors.initials: C
authors.lastname: Forsgren
authors.forename: F
authors.initials: F
authors.lastname: Hjern
authors.forename: C
authors.initials: C
authors.lastname: Lundholm
authors.forename: S
authors.initials: S
authors.lastname: Cnattingius
authors.forename: A L V
authors.initials: AL
authors.lastname: Johansson
mesh_terms: D016022:Case-Control Studies; D004238:Diverticulitis / Q000453:epidemiology / Q000601:surgery*; D005260:Female; D005402:Fistula / Q000453:epidemiology / Q000209:etiology*; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D007044:Hysterectomy / Q000009:adverse effects* / Q000706:statistics & numerical data; D007412:Intestinal Fistula / Q000453:epidemiology / Q000209:etiology; D012307:Risk Factors; D013548:Sweden / Q000453:epidemiology; D014548:Urinary Fistula / Q000453:epidemiology / Q000209:etiology; D014624:Vaginal Fistula / Q000453:epidemiology / Q000209:etiology