title: Psychometric properties of the self-report version of the Quick Inventory of Depressive Symptoms (QIDS-SR₁₆) questionnaire in patients with schizophrenia.
abstract: BACKGROUND
  Self-report instruments for the assessment of depressive symptoms in patients with psychotic disorders are scarce. The Quick Inventory of Depressive Symptoms (QIDS-SR16) may be a useful self-report instrument, but has received little attention in this field. This paper aimed to test the psychometric properties of the QIDS-SR16 questionnaire in patients with a psychotic disorder.
  
  
  METHODS
  Patients diagnosed with a psychotic disorder from health care institutions in The Netherlands were included in the study. Depressive symptoms were assessed with the QIDS-SR16 and the Calgary Depression Scale for Schizophrenia (CDSS). Psychotic symptoms were assessed with the Positive and Negative Syndrome Scale (PANSS) and extrapyramidal symptoms (EPS) with three EPS rating scales. Spearman's correlation coefficients were used to compare the total score of the QIDS-SR16 with the total scores of the CDSS, PANSS-subscales and EPS rating scales.
  
  
  RESULTS
  In a sample of 621 patients with psychotic disorders, the QIDS-SR16 showed good internal consistency (α = 0.87). The QIDS-SR16 correlated moderately with the CDSS (r = 0.44) and the PANSS subscale for emotional distress (r = 0.47). The QIDS-SR16 showed weak correlation with the PANSS subscale for negative symptoms (r = 0.28) and minimal correlation with EPS rating scales (r = 0.09-0.16).
  
  
  CONCLUSIONS
  The QIDS-SR16 may reliably assess depressive symptoms in patients with psychotic disorders, but its concurrent validity with the CDSS was rather poor in this population. We would recommend developing a new self-report questionnaire for the assessment of depressive symptoms in patients with psychotic disorders.
authors.forename: Irene M
authors.initials: IM
authors.lastname: Lako
authors.forename: Johanna T W
authors.initials: JT
authors.lastname: Wigman
authors.forename: Rianne M C
authors.initials: RM
authors.lastname: Klaassen
authors.forename: Cees J
authors.initials: CJ
authors.lastname: Slooff
authors.forename: Katja
authors.initials: K
authors.lastname: Taxis
authors.affiliation: University of Groningen, University Medical Center Groningen, University Center for Psychiatry, Rob Giel Research Center, Groningen, The Netherlands. a.a.bartels@umcg.nl.
authors.forename: Agna A
authors.initials: AA
authors.lastname: Bartels-Velthuis
mesh_terms: D000293:Adolescent; D000328:Adult; D003863:Depression / Q000175:diagnosis*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009426:Netherlands; D010555:Personality Inventory; D011569:Psychiatric Status Rating Scales / Q000706:statistics & numerical data; D011594:Psychometrics; D012565:Schizophrenic Psychology; D057566:Self Report; D055815:Young Adult