title: Radiologist interpretive volume and breast cancer screening accuracy in a Canadian organized screening program.
abstract: BACKGROUND
  To strengthen evidence on which radiologist mammography interpretive volume requirements can be based, we assessed the relation of volume to accuracy in the Quebec Breast Cancer Screening Program.
  
  
  METHODS
  Annual interpretive volume (total, screening, and diagnostic) for all 340 radiologists who interpreted 1315327 screening examinations in the period from 2000 to 2006 was obtained using provincial databases. The association of volume to sensitivity, false-positive rate, and accuracy (sensitivity/false-positive rate) was assessed by multivariable Poisson regression with robust error variance. All statistical tests were two-sided.
  
  
  RESULTS
  Radiologists consistently interpreting less than 500 mammograms annually experienced a 58% reduction in accuracy (adjusted accuracy ratio = 0.42; 95% confidence interval [CI] = 0.24 to 0.74) compared with those who consistently interpreted at least 500 mammograms annually. Moreover, accuracy increased progressively as total annual volume increased (P trend = .0005). Radiologists interpreting at least 4000 mammograms annually experienced a 32% increase in accuracy (adjusted accuracy ratio = 1.32; 95% CI = 1.13 to 1.54) compared with those interpreting 500 to 999 mammograms annually. This increase in accuracy is attributable to a reduction in false-positive rate as total volume increased (P trend = .001). Sensitivity changed little with total volume (P trend = .68). Gains in accuracy were greater up to approximately 3000 mammograms interpreted annually.
  
  
  CONCLUSIONS
  The minimum annual volume of 500 mammograms required in North America is justified; radiologist accuracy may be compromised if interpretive volume is consistently less than this requirement. Raising interpretive volume may help to reduce the frequency of false positives without loss of sensitivity. Possible gains in accuracy may be greater with increases in volume of up to approximately 3000 mammograms interpreted annually.
authors.affiliation: Affiliation of authors: Direction de l'analyse et de l'évaluation des systèmes de soins et services, Institut national de santé publique du Québec, Québec City, Canada (IT, SLC, NV, JMD, MHG, EP, JB); Unité de Recherche en Santé des Populations (URESP), Centre de recherche FRSQ du Centre hospitalier affilié universitaire de Québec, Québec city, Canada (JB).
authors.forename: Isabelle
authors.initials: I
authors.lastname: Théberge
authors.forename: Sue-Ling
authors.initials: SL
authors.lastname: Chang
authors.forename: Nathalie
authors.initials: N
authors.lastname: Vandal
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Daigle
authors.forename: Marie-Hélène
authors.initials: MH
authors.lastname: Guertin
authors.forename: Eric
authors.initials: E
authors.lastname: Pelletier
authors.forename: Jacques
authors.initials: J
authors.lastname: Brisson
mesh_terms: D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000517:prevention & control; D002170:Canada / Q000453:epidemiology; D002173:Cancer Care Facilities / Q000706:statistics & numerical data; D018270:Carcinoma, Ductal, Breast / Q000000981:diagnostic imaging; D002285:Carcinoma, Intraductal, Noninfiltrating / Q000000981:diagnostic imaging; D002983:Clinical Competence; D003937:Diagnosis, Differential; D055088:Early Detection of Cancer / Q000379:methods* / Q000706:statistics & numerical data; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D008327:Mammography / Q000706:statistics & numerical data*; D008403:Mass Screening / Q000379:methods* / Q000706:statistics & numerical data; D008875:Middle Aged; D015588:Observer Variation; D010820:Physicians / Q000706:statistics & numerical data*; D015397:Program Evaluation; D011871:Radiology / Q000706:statistics & numerical data*; D012680:Sensitivity and Specificity