title: Communicating accuracy of tests to general practitioners: a controlled study.
abstract: OBJECTIVE
  To assess the extent to which different forms of summarising diagnostic test information influence general practitioners' ability to estimate disease probabilities.
  
  
  METHODS
  Controlled questionnaire study.
  
  
  METHODS
  Three Swiss conferences in continuous medical education.
  
  
  METHODS
  263 general practitioners.
  
  
  METHODS
  Questionnaire with multiple choice questions about terms of test accuracy and a clinical vignette with the results of a diagnostic test described in three different ways (test result only, test result plus test sensitivity and specificity, test result plus the positive likelihood ratio presented in plain language).
  
  
  METHODS
  Doctors' knowledge and application of terms of test accuracy and estimation of disease probability in the clinical vignette.
  
  
  RESULTS
  The correct definitions for sensitivity and predictive value were chosen by 76% and 61% of the doctors respectively, but only 22% chose the correct answer for the post-test probability of a positive screening test. In the clinical vignette doctors given the test result only overestimated its diagnostic value (median attributed likelihood ratio (aLR)=9.0, against 2.54 reported in the literature). Providing the scan's sensitivity and specificity reduced the overestimation (median aLR=6.0) but to a lesser extent than simple wording of the likelihood ratio (median aLR=3.0).
  
  
  CONCLUSIONS
  Most general practitioners recognised the correct definitions for sensitivity and positive predictive value but did not apply them correctly. Conveying test accuracy information in simple, non-technical language improved their ability to estimate disease probabilities accurately.
authors.affiliation: Horten-Zentrum für praxisorientierte Forschung und Wissenstransfer, Universitätsspital Zürich, Bolleystrasse 40, Postfach Nord, CH-8091 Zurich, Switzerland. johann.steurer@dim.usz.ch
authors.forename: Johann
authors.initials: J
authors.lastname: Steurer
authors.forename: Joachim E
authors.initials: JE
authors.lastname: Fischer
authors.forename: Lucas M
authors.initials: LM
authors.lastname: Bachmann
authors.forename: Michael
authors.initials: M
authors.lastname: Koller
authors.forename: Gerben
authors.initials: G
authors.lastname: ter Riet
mesh_terms: D000368:Aged; D002983:Clinical Competence; D003142:Communication; D003627:Data Interpretation, Statistical; D019937:Diagnostic Techniques and Procedures; D005194:Family Practice / Q000592:standards*; D005260:Female; D006801:Humans; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D011795:Surveys and Questionnaires; D013557:Switzerland