title: Impact of the number of readers on mammography interpretation.
abstract: OBJECTIVE
  To evaluate the impact of the number of readers on sensitivity and specificity, and compare it with conference consensus reading.
  
  
  METHODS
  Eight readers read mammography films of 200 women (including 35 false-negative and 16 screen-detected cancers). The sensitivities and specificities of the two methods were calculated: either at least a single cancer-positive opinion within the group (summarized independent reading) or the cancer-positive opinion of the reader majority (conference consensus reading) was considered decisive.
  
  
  RESULTS
  The mean sensitivity for summarized independent readings of different groups was 64.7% as compared to the 43.1% mean sensitivity of conference consensus readings. The mean specificities were 92.4% and 97.7%, respectively. The greatest sensitivity of 74.5% was achieved when the readings of the four best-performing readers were combined.
  
  
  CONCLUSIONS
  The sensitivity of reading is maximal when any positive opinion within a pair or a group of readers is taken into consideration. Discordant double reading may best be judged as screening positive, and the value of a third opinion should be questioned.
authors.affiliation: Department of Radiology, Helsinki University Central Hospital, Hospital District of Helsinki and Uusimaa, Finland. katja.hukkinen@hus.fi
authors.forename: K
authors.initials: K
authors.lastname: Hukkinen
authors.forename: L
authors.initials: L
authors.lastname: Kivisaari
authors.forename: T
authors.initials: T
authors.lastname: Vehmas
mesh_terms: D001943:Breast Neoplasms / Q000000981:diagnostic imaging*; D002983:Clinical Competence; D005260:Female; D006801:Humans; D008327:Mammography / Q000379:methods*; D008403:Mass Screening / Q000592:standards* / Q000706:statistics & numerical data; D008875:Middle Aged; D015588:Observer Variation; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012680:Sensitivity and Specificity