title: Prevalence of colonoscopy before age 50.
abstract: OBJECTIVE
  Describe the prevalence of colonoscopy before age 50, when guidelines recommend initiation of colorectal cancer screening for average risk individuals.
  
  
  METHODS
  We assembled administrative health records that captured receipt of colonoscopy between 40 and 49-years of age for a cohort of 204,758 50-year-old members of four US health plans and used backward recurrence time models to estimate trends in receipt of colonoscopy before age 50 and variation in early colonoscopy by age and sex. We also used self-reported receipt of colonoscopy from 27,157 40- to 49-year-old respondents to the 2010 National Health Interview Survey (NHIS) to estimate the association between early colonoscopy and sex, race/ethnicity, and geographic location based on logistic regression models that accounted for the complex NHIS sampling design.
  
  
  RESULTS
  About 5% of the health plan cohort had a record of colonoscopy before age 50. Receipt of early colonoscopy increased significantly from 1999 to 2010 (test for linear trend, p<0.0001), was more likely among women than men (RR=1.9, 95% CI 1.14-1.24) and in the east coast health plan compared to west coast and Hawaii plans. The NHIS analysis found that early colonoscopy was more likely in Northeastern residents compared to residents in the West (odds ratio=1.75, 95% CI 1.28-2.39).
  
  
  CONCLUSIONS
  Colonoscopy before age 50 is increasingly common.
authors.affiliation: RAND Corporation, Santa Monica, CA, United States. Electronic address: crutter@rand.org.
authors.forename: Carolyn M
authors.initials: CM
authors.lastname: Rutter
authors.affiliation: Marshfield Clinic Research Foundation, Epidemiology Research Center, Marshfield, WI, United States.
authors.forename: Robert T
authors.initials: RT
authors.lastname: Greenlee
authors.affiliation: Group Health Research Institute, Seattle,` WA, United States.
authors.forename: Eric
authors.initials: E
authors.lastname: Johnson
authors.affiliation: Geisinger Center for Health Research, Danville, PA, United States; Henry Ford Health System, Department of Pathology, Detroit, MI, United States.
authors.forename: Azadeh
authors.initials: A
authors.lastname: Stark
authors.affiliation: Kaiser Permanente, Center for Health Research Northwest, Portland, OR, United States.
authors.forename: Sheila
authors.initials: S
authors.lastname: Weinmann
authors.affiliation: Group Health Research Institute, Seattle,` WA, United States.
authors.forename: Aruna
authors.initials: A
authors.lastname: Kamineni
authors.affiliation: Minnesota Department of Health, Minnesota Cancer Surveillance System, Saint Paul, MN, United States.
authors.forename: Kenneth
authors.initials: K
authors.lastname: Adams
authors.affiliation: Department of Family Medicine and Community Health, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States.
authors.forename: Chyke A
authors.initials: CA
authors.lastname: Doubeni
mesh_terms: D000328:Adult; D000367:Age Factors; D015331:Cohort Studies; D003110:Colonic Neoplasms / Q000175:diagnosis / Q000517:prevention & control*; D003113:Colonoscopy / Q000706:statistics & numerical data*; D055088:Early Detection of Cancer / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors; D012737:Sex Factors; D014481:United States
keywords: Colorectal cancer screening; HMO Cancer Research Network; Screening uptake