title: Long-term risk of acute diverticulitis among patients with incidental diverticulosis found during colonoscopy.
abstract: OBJECTIVE
  Colonic diverticulosis is the most common finding during routine colonoscopy, and patients often question the significance of these lesions. Guidelines state that these patients have a 10% to 25% lifetime risk of developing acute diverticulitis. However, this value was determined based on limited data, collected before population-based colonoscopy, so the true number of cases of diverticulosis was not known. We measured the long-term risk of acute diverticulitis among patients with confirmed diverticulosis discovered incidentally on colonoscopy.
  
  
  METHODS
  We performed a retrospective study using administrative and clinical data from the Veterans Affairs Greater Los Angeles Healthcare System, collecting data on patients who underwent colonoscopies from January 1996 through January 2011. We identified patients diagnosed with diverticulosis, determined incidence rates per 1000 patient-years, and analyzed a subgroup of patients with rigorously defined events confirmed by imaging or surgery. We used a Cox proportional hazards model to identify factors associated with the development of diverticulitis.
  
  
  RESULTS
  We identified 2222 patients with baseline diverticulosis. Over an 11-year follow-up period, 95 patients developed diverticulitis (4.3%; 6 per 1000 patient-years); of these, 23 met the rigorous definition of diverticulitis (1%; 1.5 per 1000 patient-years). The median time-to-event was 7.1 years. Each additional decade of age at time of diagnosis reduced the risk for diverticulitis by 24% (hazard ratio, 0.76; 95% confidence interval, 0.6-0.9).
  
  
  CONCLUSIONS
  Based on a study of the Veterans Affairs Greater Los Angeles Healthcare System, only about 4% of patients with diverticulosis develop acute diverticulitis, contradicting the common belief that diverticulosis has a high rate of progression. We also found that younger patients have a higher risk of diverticulitis, with risk increasing per year of life. These results can help inform patients with diverticulosis about their risk of developing acute diverticulitis.
authors.affiliation: University of California Los Angeles/Veteran's Affairs Center for Outcomes Research and Education, Los Angeles, California.
authors.forename: Kamyar
authors.initials: K
authors.lastname: Shahedi
authors.forename: Garth
authors.initials: G
authors.lastname: Fuller
authors.forename: Roger
authors.initials: R
authors.lastname: Bolus
authors.forename: Erica
authors.initials: E
authors.lastname: Cohen
authors.forename: Michelle
authors.initials: M
authors.lastname: Vu
authors.forename: Rena
authors.initials: R
authors.lastname: Shah
authors.forename: Nikhil
authors.initials: N
authors.lastname: Agarwal
authors.forename: Marc
authors.initials: M
authors.lastname: Kaneshiro
authors.forename: Mary
authors.initials: M
authors.lastname: Atia
authors.forename: Victoria
authors.initials: V
authors.lastname: Sheen
authors.forename: Nicole
authors.initials: N
authors.lastname: Kurzbard
authors.forename: Martijn G H
authors.initials: MG
authors.lastname: van Oijen
authors.forename: Linnette
authors.initials: L
authors.lastname: Yen
authors.forename: Paul
authors.initials: P
authors.lastname: Hodgkins
authors.forename: M Haim
authors.initials: MH
authors.lastname: Erder
authors.forename: Brennan
authors.initials: B
authors.lastname: Spiegel
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003113:Colonoscopy; D004238:Diverticulitis / Q000453:epidemiology*; D004240:Diverticulum / Q000150:complications* / Q000175:diagnosis*; D005260:Female; D006801:Humans; D015141:Los Angeles / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012189:Retrospective Studies; D018570:Risk Assessment; D014728:Veterans
keywords: BMI; CT; Colon; Diverticular Disease; ICD-9; International Classification of Diseases, 9th revision; Pouch; Prognosis; VA; VAGLAHS; Veteran's Affairs; Veterans Affairs Greater Los Angeles Healthcare System; body mass index; computed tomography