title: Comparison of cumulative false-positive risk of screening mammography in the United States and Denmark.
abstract: BACKGROUND
  In the United States (US), about one-half of women screened with annual mammography have at least one false-positive test after ten screens. The estimate for European women screened ten times biennially is much lower. We evaluate to what extent screening interval, mammogram type, and statistical methods, can explain the reported differences.
  
  
  METHODS
  We included all screens from women first screened at age 50-69 years in the US Breast Cancer Surveillance Consortium (BCSC) (n=99,455) between 1996-2010, and from two population-based mammography screening programs in Denmark (n=230,452 and n=400,204), between 1991-2012 and 1993-2013, respectively. Model-based cumulative false-positive risks were computed for the entire sample, using two statistical methods (Hubbard Njor) previously used to estimate false-positive risks in the US and Europe.
  
  
  RESULTS
  Empirical cumulative risk of at least one false-positive test after eight (annual or biennial) screens was 41.9% in BCSC, 16.1% in Copenhagen, and 7.4% in Funen. Variation in screening interval and mammogram type did not explain the differences by country. Using the Hubbard method, the model-based cumulative risks after eight screens was 45.1% in BCSC, 9.6% in Copenhagen, and 8.8% in Funen. Using the Njor method, these risks were estimated to be 43.6, 10.9 and 8.0%.
  
  
  CONCLUSIONS
  Choice of statistical method, screening interval and mammogram type does not explain the substantial differences in cumulative false-positive risk between the US and Europe.
authors.affiliation: Department of Public Health, University of Copenhagen, Copenhagen K, Denmark. Electronic address: kkja@sund.ku.dk.
authors.forename: Katja
authors.initials: K
authors.lastname: Kemp Jacobsen
authors.affiliation: Group Health Research Institute, Seattle, WA, United States.
authors.forename: Linn
authors.initials: L
authors.lastname: Abraham
authors.affiliation: Group Health Research Institute, Seattle, WA, United States.
authors.forename: Diana S M
authors.initials: DS
authors.lastname: Buist
authors.affiliation: Department of Biostatistics and Epidemiology, University of Pennsylvania, Philadelphia, PA, United States.
authors.forename: Rebecca A
authors.initials: RA
authors.lastname: Hubbard
authors.affiliation: Group Health Research Institute, Seattle, WA, United States.
authors.forename: Ellen S
authors.initials: ES
authors.lastname: O'Meara
authors.affiliation: Department of Surgery, University of Vermont, Burlington, VT, United States.
authors.forename: Brian L
authors.initials: BL
authors.lastname: Sprague
authors.affiliation: Department of Epidemiology & Biostatistics, University of California, San Francisco, CA, United States; General Internal Medicine Section, Department of Veterans Affairs, University of California, San Francisco, CA, United States.
authors.forename: Karla
authors.initials: K
authors.lastname: Kerlikowske
authors.affiliation: Center of Diagnostic Imaging, Copenhagen University Hospital, Rigshospitalet, Denmark.
authors.forename: Ilse
authors.initials: I
authors.lastname: Vejborg
authors.affiliation: Department of Public Health, University of Copenhagen, Copenhagen K, Denmark.
authors.forename: My
authors.initials: M
authors.lastname: Von Euler-Chelpin
authors.affiliation: Department of Public Health, University of Copenhagen, Copenhagen K, Denmark.
authors.forename: Sisse Helle
authors.initials: SH
authors.lastname: Njor
mesh_terms: D000368:Aged; D001943:Breast Neoplasms / Q000000981:diagnostic imaging*; D003718:Denmark; D055088:Early Detection of Cancer / Q000379:methods; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D008327:Mammography / Q000379:methods; D008875:Middle Aged; D012306:Risk; D014481:United States
keywords: Breast neoplasm; False-positive reactions; Mammography; Mass screening; Methods