title: Predicting the risk of a false-positive test for women following a mammography screening programme.
abstract: OBJECTIVE
  The objectives of this study was to provide a simple estimate of the cumulative risk of a false-positive test for women participating in mammography screening. To test the method, we used data from two well-established, organized mammography screening programmes offering biennial screening to women aged 50-69 years in Copenhagen and Fyn, Denmark.
  
  
  METHODS
  We defined the outcome from a screen as being either a false-positive test or not a false-positive test. We then tested whether the outcomes from subsequent screens were independent, and afterwards estimated the risk over 10 screens of a false-positive test, i.e. the risk of getting at least one false-positive test for a woman participating in all 10 screens typically offered in Europe.
  
  
  RESULTS
  The outcomes of subsequent screens were found to be independent. After completion of screening rounds 3-5, the risk of a false-positive test over 10 screens was predicted to be 15.8-21.5% for a woman participating in the programme in Copenhagen, and 8.1-9.6% for a woman participating in the programme in Fyn.
  
  
  CONCLUSIONS
  Our study showed that a relatively robust prediction of the risk of a false-positive test over 10 screens can be calculated in a simple way relatively early after the start of a mammography screening programme.
authors.affiliation: Institute of Public Health, University of Copenhagen, Øster Farigmagsgade 5, opg. B, DK-1014 Copenhagen K, Denmark.
authors.forename: Sisse Helle
authors.initials: SH
authors.lastname: Njor
authors.forename: Anne Helene
authors.initials: AH
authors.lastname: Olsen
authors.forename: Walter
authors.initials: W
authors.lastname: Schwartz
authors.forename: Ilse
authors.initials: I
authors.lastname: Vejborg
authors.forename: Elsebeth
authors.initials: E
authors.lastname: Lynge
mesh_terms: D000368:Aged; D001943:Breast Neoplasms / Q000175:diagnosis*; D003718:Denmark; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D008327:Mammography / Q000379:methods / Q000592:standards / Q000706:statistics & numerical data*; D008403:Mass Screening / Q000379:methods / Q000592:standards / Q000706:statistics & numerical data*; D008875:Middle Aged; D012307:Risk Factors