title: Community-based screening by colonoscopy or computed tomographic colonography in asymptomatic average-risk subjects.
abstract: OBJECTIVE
  Visualizing the entire colorectum in screening is an advantage of colonoscopy, and also computed tomographic (CT) colonography, another potentially suitable screening test. Our objective was to compare screening CT colonography and colonoscopy in an asymptomatic average-risk population, and to determine whether providing a choice of tests increased participation.
  
  
  METHODS
  One thousand and four hundred subjects from the general community, randomly selected from the parliamentary electoral roll, were allocated one of three screening groups: colonoscopy, CT colonography, or a choice of these tests, and were sent an institutional letter of invitation. Those with symptoms, colorectal cancer in first-degree relatives, or colonoscopy within 5 yr were ineligible. Outcome measures were participation, acceptability of screening, and yield for advanced colorectal neoplasia in participants.
  
  
  RESULTS
  Of the subjects, 24.9% were ineligible; the overall participation rate was 18.2% (184/1,009). Participation in each screening group was not different. Both tests were accompanied by the same high levels of acceptability; most participants found colonoscopy (87%) and CT colonography (67%, p < 0.001) less unpleasant than expected. About 29% (26/89) CT colonography subjects had a positive screening test. The yield of advanced colorectal neoplasia was 8.7% (95% CI 5-14%), with no difference in yield between tests.
  
  
  CONCLUSIONS
  Colorectal neoplasia screening by colonoscopy or CT colonography was associated with modest participation, high levels of acceptability, and similar yield for advanced colorectal neoplasia. Providing a choice of test did not increase participation.
authors.affiliation: Department of Diagnostic and Interventional Radiology, Royal Perth Hospital, Western Australia, Australia.
authors.forename: Rosie G
authors.initials: RG
authors.lastname: Scott
authors.forename: John T
authors.initials: JT
authors.lastname: Edwards
authors.forename: Lin
authors.initials: L
authors.lastname: Fritschi
authors.forename: Noellene M
authors.initials: NM
authors.lastname: Foster
authors.forename: Richard M
authors.initials: RM
authors.lastname: Mendelson
authors.forename: Geoffrey M
authors.initials: GM
authors.lastname: Forbes
mesh_terms: D017677:Age Distribution; D000368:Aged; D000704:Analysis of Variance; D001315:Australia / Q000453:epidemiology; D023881:Colonography, Computed Tomographic; D003113:Colonoscopy / Q000379:methods*; D015179:Colorectal Neoplasms / Q000175:diagnosis* / Q000453:epidemiology; D016001:Confidence Intervals; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008403:Mass Screening / Q000379:methods*; D008875:Middle Aged; D011159:Population Surveillance; D011237:Predictive Value of Tests; D011336:Probability; D012016:Reference Values; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D017678:Sex Distribution