title: The psychometric discriminative properties of the Peters et al Delusions Inventory: a receiver operating characteristic curve analysis.
abstract: OBJECTIVE
  To establish sensitivity, specificity, and discriminative validity of the Peters et al Delusions Inventory (PDI), a recently released self-compiled questionnaire aimed at measuring psychosis proneness in the general population.
  
  
  METHODS
  Eighty-one patients diagnosed with a mental disorder with psychotic features (schizophrenia, schizoaffective disorder, bipolar disorder, major depression) and 210 putatively healthy individuals were invited to complete the PDI and the brief version of the General Health Questionnaire (GHQ-12). The receiver operating characteristic analysis has been used to extract the best threshold to discriminate between cases, those with a psychotic disorder, and noncases, those without a psychotic disorder.
  
  
  RESULTS
  The best PDI threshold in discriminating between cases and noncases was 8 (sensitivity, 74%; specificity, 79%). The corresponding figures of sensitivity and specificity for a GHQ-12 cutoff of 6 were 63% and 83%, respectively. The value of the area under the receiver operating characteristic curve was found to be higher for the PDI (0.815) than for the GHQ-12 (0.770), although at a barely detectable, statistically significant difference (Z = 1.45, P = .073).
  
  
  CONCLUSIONS
  The expected high negative predictive value of the PDI (96%) in the general population suggests it will be a valuable tool in future research on psychosis proneness.
authors.affiliation: Department of Psychology, University of Cagliari, 09123 Cagliari, Italy. apreti@tin.it
authors.forename: Antonio
authors.initials: A
authors.lastname: Preti
authors.forename: Marco B L
authors.initials: MB
authors.lastname: Rocchi
authors.forename: Davide
authors.initials: D
authors.lastname: Sisti
authors.forename: Tania
authors.initials: T
authors.lastname: Mura
authors.forename: Sebastiana
authors.initials: S
authors.lastname: Manca
authors.forename: Sara
authors.initials: S
authors.lastname: Siddi
authors.forename: Donatella Rita
authors.initials: DR
authors.lastname: Petretto
authors.forename: Carmelo
authors.initials: C
authors.lastname: Masala
mesh_terms: D000328:Adult; D000368:Aged; D001714:Bipolar Disorder / Q000453:epidemiology; D003702:Delusions / Q000175:diagnosis* / Q000453:epidemiology* / Q000523:psychology; D003865:Major Depressive Disorder / Q000453:epidemiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011594:Psychometrics / Q000706:statistics & numerical data; D011618:Psychotic Disorders / Q000453:epidemiology; D012372:ROC Curve; D015203:Reproducibility of Results; D012559:Schizophrenia / Q000453:epidemiology; D012680:Sensitivity and Specificity; D011795:Surveys and Questionnaires