title: Comparing Rasch analyses probability estimates to sensitivity, specificity and likelihood ratios when examining the utility of medical diagnostic tests.
abstract: BACKGROUND
  Medical diagnostic tests are evaluated based on measures of sensitivity (Sn), specificity (Sp), and likelihood ratios (LR). These procedures are limited in the event of a biased gold standard or missing data. Interpretations of these measures are frequently inappropriate.
  
  
  OBJECTIVE
  The Rasch measurement model (RMM) was examined as a method to provide evidence of diagnostic test utility in order to overcome the limitations of Sn, Sp, and LR.
  
  
  METHODS
  Patients suspected of a knee ligament tear (n = 825) were studied, by evaluating four diagnostic tests. The RMM probability estimates for each test were compared to estimates of Sn, Sp, and LR.
  
  
  RESULTS
  The RMM provided probability estimates for the diagnosis that were comparable to likelihood ratios. These probability estimates correlated with the estimates of Sn, Sp, and LR. The RMM estimates were not affected by missing data.
  
  
  CONCLUSIONS
  The RMM may provide an alternative means to study the utility of medical diagnostic tests to estimate the probability of disease presence/absence.
authors.affiliation: Department of Physical Therapy, The Medical College of Ohio, Toledo, OH 43614-5803, USA. dcipriani@mco.edu
authors.forename: Daniel
authors.initials: D
authors.lastname: Cipriani
authors.forename: Christine
authors.initials: C
authors.lastname: Fox
authors.forename: Sadik
authors.initials: S
authors.lastname: Khuder
authors.forename: Nancy
authors.initials: N
authors.lastname: Boudreau
mesh_terms: D000070598:Anterior Cruciate Ligament Injuries; D003955:Diagnostic Tests, Routine / Q000592:standards* / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D007718:Knee Injuries / Q000175:diagnosis*; D016013:Likelihood Functions; D008297:Male; D012680:Sensitivity and Specificity