title: Screening and assessing ideas and delusions of reference using a semi-structured interview scale: a validation study of the Ideas of Reference Interview Scale (IRIS) in early psychosis patients.
abstract: BACKGROUND
  Ideas and delusions of reference (IOR/DOR) are an important but underrecognized research target. Difficulty in their reliable assessment has been a barrier. A screening and assessment tool incorporating a self-information processing framework, the Ideas of Reference Interview Scale (IRIS), was developed and validated in patients with early psychosis.
  
  
  METHODS
  Comprehensive review of IOR/DOR phenomena in the literature and pilot interviews were conducted for scale item development. Self-referential themes were summarized into 15 items. A consecutive sample of 137 outpatients with early psychosis was interviewed using IRIS. Their IOR/DOR experiences were also rated independently by clinicians on the Scale for the Assessment of Positive Symptoms (SAPS) and self-rated using the IOR subscale on the Schizotypal Personality Questionnaire (SPQ). Inter-rater reliability of IRIS was examined in a subsample of 15 participants.
  
  
  RESULTS
  IRIS demonstrated good internal consistency (Cronbach's alpha 0.80), inter-rater reliability (intraclass correlation coefficient 0.95), and divergent validity with other symptoms. IRIS correlated satisfactorily with the IOR/DOR item or subscale on SAPS and SPQ (Spearman's rho = 0.71 and 0.47, respectively).
  
  
  CONCLUSIONS
  IRIS provided a reliable high-resolution tool for progressing single-symptom research into IOR/DOR, a potential target feature of schizophrenia. The scale allows future investigation into self-referential processing and detailed phenomenological comparison in different clinical, subclinical, and healthy populations.
authors.affiliation: Department of Psychiatry, The University of Hong Kong, Hong Kong. ghywong@hku.hk
authors.forename: Gloria H Y
authors.initials: GH
authors.lastname: Wong
authors.forename: Christy L M
authors.initials: CL
authors.lastname: Hui
authors.forename: Jennifer Y M
authors.initials: JY
authors.lastname: Tang
authors.forename: Cindy P Y
authors.initials: CP
authors.lastname: Chiu
authors.forename: May M L
authors.initials: MM
authors.lastname: Lam
authors.forename: Sherry K W
authors.initials: SK
authors.lastname: Chan
authors.forename: W C
authors.initials: WC
authors.lastname: Chang
authors.forename: Eric Y H
authors.initials: EY
authors.lastname: Chen
mesh_terms: D000293:Adolescent; D000328:Adult; D003702:Delusions / Q000175:diagnosis* / Q000209:etiology*; D005260:Female; D006801:Humans; D007406:Interview, Psychological / Q000379:methods* / Q000592:standards; D008297:Male; D008403:Mass Screening / Q000379:methods*; D011569:Psychiatric Status Rating Scales; D011618:Psychotic Disorders / Q000150:complications* / Q000175:diagnosis; D015203:Reproducibility of Results; D055815:Young Adult