title: A new Integrated Negative Symptom structure of the Positive and Negative Syndrome Scale (PANSS) in schizophrenia using item response analysis.
abstract: BACKGROUND
  Debate persists with regard to how best to categorize the syndromal dimension of negative symptoms in schizophrenia. The aim was to first review published Principle Components Analysis (PCA) of the PANSS, and extract items most frequently included in the negative domain, and secondly, to examine the quality of items using Item Response Theory (IRT) to select items that best represent a measurable dimension (or dimensions) of negative symptoms.
  
  
  METHODS
  First, 22 factor analyses and PCA met were included. Second, using a large dataset (n=7187) of participants in clinical trials with chronic schizophrenia, we extracted items loading on one or more PCA. Third, items not loading with a value of ≥ 0.5, or loading on more than one component with values of ≥ 0.5 were discarded. Fourth, resulting items were included in a non-parametric IRT and retained based on Option Characteristic Curves (OCCs) and Item Characteristic Curves (ICCs).
  
  
  RESULTS
  15 items loaded on a negative domain in at least one study, with Emotional Withdrawal loading on all studies. Non-parametric IRT retained nine items as an Integrated Negative Factor: Emotional Withdrawal, Blunted Affect, Passive/Apathetic Social Withdrawal, Poor Rapport, Lack of Spontaneity/Conversation Flow, Active Social Avoidance, Disturbance of Volition, Stereotyped Thinking and Difficulty in Abstract Thinking.
  
  
  CONCLUSIONS
  This is the first study to use a psychometric IRT process to arrive at a set of negative symptom items. Future steps will include further examination of these nine items in terms of their stability, sensitivity to change, and correlations with functional and cognitive outcomes.
authors.affiliation: Nathan S. Kline Institute for Psychiatric Research, 140 Old Orangeburg Road, Orangeburg, NY 10962, United States; ProPhase LLC, 3 Park Avenue, 37th Floor, New York, NY 10016, United States; Manhattan Psychiatric Center, 1 Wards Island Complex, NY, NY 10035, United States. Electronic address: akhan@nki.rfmh.org.
authors.forename: Anzalee
authors.initials: A
authors.lastname: Khan
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Lindenmayer
authors.forename: Mark
authors.initials: M
authors.lastname: Opler
authors.forename: Christian
authors.initials: C
authors.lastname: Yavorsky
authors.forename: Brian
authors.initials: B
authors.lastname: Rothman
authors.forename: Luka
authors.initials: L
authors.lastname: Lucic
mesh_terms: D057565:Apathy; D016206:Databases, Bibliographic / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D008297:Male; D025341:Principal Component Analysis; D011569:Psychiatric Status Rating Scales; D011594:Psychometrics; D012559:Schizophrenia / Q000175:diagnosis / Q000503:physiopathology*; D012565:Schizophrenic Psychology; D018709:Statistics, Nonparametric
keywords: Item response analysis; Negative symptoms; PANSS