title: Construct validity of 2 measures to assess reasons for antipsychotic discontinuation and continuation from patients' and clinicians' perspectives in a clinical trial.
abstract: BACKGROUND
  Little is known about the specific reasons for antipsychotic discontinuation or continuation from patients' or clinicians' perspectives. This study aimed to assess the construct validity of 2 new measures of the Reasons for Antipsychotic Discontinuation/Continuation (RAD): RAD-I (a structured interview assessing the patient's perspective) and RAD-Q (a questionnaire assessing the clinician's perspective).
  
  
  METHODS
  Data were used from a 12-week antipsychotic trial of schizophrenia patients in which the RAD was administered at study entry and at study completion (or discontinuation). Construct validity was assessed through comparisons of RAD responses, clinicians' responses to a standard patient disposition form identifying reasons for patient's study discontinuation, and several standard psychiatric measures. Percent agreement quantified the correspondence between patient and clinician scores.
  
  
  RESULTS
  Patients indicating lack of improvement/worsening of positive symptoms as a 'somewhat' to 'primary' reason for medication discontinuation had statistically significantly less improvement in Positive and Negative Syndrome Scale positive score than patients not reporting these as a reason (concurrent validity). Similar results were observed for the RAD negative symptom, functional, social support, and adherence items, whereas the mood and cognitive items were not significantly associated with change scores on standard psychiatric measures. Responses to the RAD were also weakly associated with variables that theoretically should not be related to them (divergent validity). Level of agreement between the clinician- and patient-rated RAD scores was high (60%-100%).
  
  
  CONCLUSIONS
  Initial validation of the RAD suggests that the instruments are valid tools for gathering detailed information regarding reasons for antipsychotic discontinuation and continuation from patients' and clinicians' perspectives.
authors.affiliation: Eli Lilly and Company, Lilly Corporate Center, DC 5024, Indianapolis, IN 46285, USA. d.faries@lilly.com
authors.forename: Douglas
authors.initials: D
authors.lastname: Faries
authors.forename: Haya
authors.initials: H
authors.lastname: Ascher-Svanum
authors.forename: Glenn
authors.initials: G
authors.lastname: Phillips
authors.forename: Allen W
authors.initials: AW
authors.lastname: Nyhuis
authors.forename: Tomoko
authors.initials: T
authors.lastname: Sugihara
authors.forename: Virginia
authors.initials: V
authors.lastname: Stauffer
authors.forename: Bruce J
authors.initials: BJ
authors.lastname: Kinon
mesh_terms: D000328:Adult; D014150:Antipsychotic Agents / Q000627:therapeutic use*; D003072:Cognition Disorders / Q000209:etiology; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007406:Interview, Psychological / Q000379:methods*; D007407:Interviews as Topic; D008297:Male; D055118:Medication Adherence; D008875:Middle Aged; D010865:Pilot Projects; D011594:Psychometrics / Q000379:methods*; D011599:Psychopathology / Q000592:standards; D011618:Psychotic Disorders / Q000175:diagnosis / Q000188:drug therapy; D011788:Quality of Life; D015203:Reproducibility of Results; D018967:Risperidone / Q000627:therapeutic use; D012559:Schizophrenia / Q000175:diagnosis / Q000188:drug therapy*; D011795:Surveys and Questionnaires / Q000592:standards*
chemical_list: D014150:Antipsychotic Agents; D018967:Risperidone