title: An illustration of how a self-report diagnostic screening scale could improve the internal validity of antidepressant efficacy trials.
abstract: BACKGROUND
  During the past 20 years semi-structured diagnostic interviews have been the standard for diagnostic evaluations in research relying on reliable and valid psychiatric assessment and diagnosis; however, only a minority of antidepressant efficacy trials (AETs) employ these interviews. This might be important insofar as several studies have found that clinicians conducting unstructured clinical interviews underrecognize diagnostic comorbidity. Because of the financial incentives to recruit patients into AETs quickly, there is little incentive to vigorously determine the presence of comorbid conditions that should result in exclusion from the trial. In the present report we demonstrate how a self-report diagnostic screening scale could be used to identify systematic differences in diagnostic practice across settings, and how such a scale could be used to compare samples of patients who pass screening evaluations and are accepted into an AET.
  
  
  METHODS
  Depressed patients completed the Psychiatric Diagnostic Screening Questionnaire (PDSQ), and were evaluated with either an unstructured clinical interview or with the Structured Clinical Interview for DSM-IV (SCID).
  
  
  RESULTS
  The two samples were clinically comparable based on their scores on the self-administered PDSQ. Consistent with the greater thoroughness of the SCID, compared to unstructured diagnostic evaluations, more patients administered the SCID were diagnosed with comorbid conditions. After excluding patients with disorders that might be the basis for exclusion from an AET, the two samples then differed in their scores on the PDSQ. That is, more patients in the sample evaluated by an unstructured interview had 'occult' pathology than patients evaluated with the SCID.
  
  
  CONCLUSIONS
  These findings demonstrate how systematic differences in diagnostic practice might be detected across sites when conducting AETs.
  
  
  CONCLUSIONS
  The study was conducted with patients in a single outpatient clinical practice rather than participants of a multi-site trial.
authors.affiliation: Department of Psychiatry and Human Behavior, Brown University School of Medicine, Rhode Island Hospital, Providence, RI, USA. mzimmerman@lifespan.org
authors.forename: Mark
authors.initials: M
authors.lastname: Zimmerman
authors.forename: Iwona
authors.initials: I
authors.lastname: Chelminski
authors.forename: Michael
authors.initials: M
authors.lastname: Posternak
mesh_terms: D000328:Adult; D000928:Antidepressive Agents / Q000627:therapeutic use; D015897:Comorbidity; D003866:Depressive Disorder / Q000175:diagnosis* / Q000188:drug therapy* / Q000453:epidemiology; D017831:Diagnosis, Dual (Psychiatry); D005260:Female; D006801:Humans; D007406:Interview, Psychological / Q000379:methods; D008297:Male; D008403:Mass Screening / Q000379:methods*; D018579:Patient Selection; D010555:Personality Inventory / Q000706:statistics & numerical data*; D015995:Prevalence; D011569:Psychiatric Status Rating Scales / Q000706:statistics & numerical data; D011594:Psychometrics; D015203:Reproducibility of Results; D019966:Substance-Related Disorders / Q000175:diagnosis / Q000453:epidemiology; D011795:Surveys and Questionnaires; D016896:Treatment Outcome
chemical_list: D000928:Antidepressive Agents