title: Evaluation of a risk index for advanced proximal neoplasia of the colon.
abstract: BACKGROUND
  A clinical risk index that uses distal colorectal findings at flexible sigmoidoscopy (FS) in conjunction with easily determined risk factors for advanced proximal neoplasia (APN) may be useful for tailoring or prioritizing screening with colonoscopy.
  
  
  OBJECTIVE
  To conduct an external evaluation of a previously published risk index in a large, well-characterized cohort.
  
  
  METHODS
  Cross-sectional.
  
  
  METHODS
  Teaching hospital and colorectal cancer screening center.
  
  
  METHODS
  A total of 5139 asymptomatic persons aged 50 to 74 (54.9% women) with a mean age (±SD) of 58.3 (±6.2) years.
  
  
  METHODS
  Between 2003 and 2011, all participants underwent a complete screening colonoscopy and removal of all polyps.
  
  
  METHODS
  Participants were classified as low, intermediate, or high risk for APN, based on their composite risk index scores. The concordance or c-statistic was used to measure discriminating ability of the risk index.
  
  
  RESULTS
  A total of 167 persons (3.2%) had APN. The prevalence of those with APN among low-, intermediate-, and high-risk categories was 2.1%, 2.9%, and 6.5%, respectively. High-risk individuals were 3.2 times more likely to have APN compared with those in the low-risk category. The index did not discriminate well between those in the low- and intermediate-risk categories. The c-statistic for the overall index was 0.62 (95% confidence interval, 0.58-0.66).
  
  
  CONCLUSIONS
  Distal colorectal findings were derived from colonoscopies and not FS itself.
  
  
  CONCLUSIONS
  The risk index discriminated between those at low risk and those at high risk, but it had limited ability to discriminate between low- and intermediate-risk categories for prevalent APN. Information on other risk factors may be needed to tailor, or prioritize, access to screening colonoscopy.
authors.affiliation: Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, Toronto, Canada.
authors.forename: Arlinda
authors.initials: A
authors.lastname: Ruco
authors.affiliation: Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, Toronto, Canada.
authors.forename: David
authors.initials: D
authors.lastname: Stock
authors.affiliation: Department of Medicine, University of Calgary, Calgary, Canada.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Hilsden
authors.affiliation: Population, Public & Aboriginal Health, Alberta Health Services, Calgary, Alberta, Canada.
authors.forename: S Elizabeth
authors.initials: SE
authors.lastname: McGregor
authors.affiliation: Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, Toronto, Canada; Institute for Clinical Evaluative Sciences, Toronto, Canada; Institute of Health Policy, Management and Evaluation, University of Toronto, Toronto, Canada; Dalla Lana School of Public Health, University of Toronto, Toronto, Canada.
authors.forename: Lawrence F
authors.initials: LF
authors.lastname: Paszat
authors.affiliation: Institute for Clinical Evaluative Sciences, Toronto, Canada.
authors.forename: Refik
authors.initials: R
authors.lastname: Saskin
authors.affiliation: Institute for Clinical Evaluative Sciences, Toronto, Canada; Institute of Health Policy, Management and Evaluation, University of Toronto, Toronto, Canada; Dalla Lana School of Public Health, University of Toronto, Toronto, Canada; Prevention and Cancer Control, Cancer Care Ontario, Toronto, Canada; Department of Medicine, University of Toronto, Toronto, Canada.
authors.forename: Linda
authors.initials: L
authors.lastname: Rabeneck
mesh_terms: D000368:Aged; D003106:Colon / Q000473:pathology*; D003111:Colonic Polyps / Q000601:surgery; D003113:Colonoscopy; D015179:Colorectal Neoplasms / Q000175:diagnosis* / Q000473:pathology; D003430:Cross-Sectional Studies; D055088:Early Detection of Cancer / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008403:Mass Screening / Q000379:methods; D008875:Middle Aged; D009361:Neoplasm Invasiveness / Q000175:diagnosis*; D009367:Neoplasm Staging / Q000379:methods*; D015995:Prevalence; D018570:Risk Assessment