title: Symptom structure and severity: a comparison of responses to the positive and negative syndrome scale (PANSS) between patients with PTSD or schizophrenia.
abstract: OBJECTIVE
  To describe and compare the structure and relative severity of symptoms in clinical trial patients diagnosed with Post Traumatic Stress Disorder (PTSD) or schizophrenia using the Positive and Negative Syndrome Scale (PANSS), developed originally to evaluate symptoms of schizophrenia.
  
  
  METHODS
  This secondary data analysis used baseline PANSS symptom ratings (n=267) from a six-month multicenter randomized placebo-controlled trial of adjunctive risperidone in patients with chronic military-related PTSD. First, using a split-half design, Exploratory Factor Analysis (EFA) was employed to identify independent factors which were then compared to published factor structures for schizophrenia. Next, Confirmatory Factor Analysis (CFA) was applied to the second half of the sample to compare the results of the EFA and published factor structures. Finally, T-tests were used to compare the severity of factor scores between the PTSD sample and the baseline PANSS ratings from the Clinical Antipsychotic Trial for Intervention Effectiveness (CATIE) schizophrenia sample (n=1460).
  
  
  RESULTS
  EFA suggested five factors similar to those identified in a summary of 29 schizophrenia studies by Wallwork (Schizophrenia Research, 137:246-250). CFA showed that the five factor Wallwork model fit the data better than the EFA, although both had relatively high goodness of fit. T-tests showed that the PTSD sample had more severe symptoms on the Depressive factor, and the schizophrenia sample on the Positive, Negative, and Disorganized factors, with no significant difference on the Excited factor.
  
  
  CONCLUSIONS
  Veterans with PTSD had similar symptom structure to patients with schizophrenia on the PANSS, but were less symptomatic on psychosis-related factors and more symptomatic on depression. Dimensional symptom factors can be virtually the same across diagnoses.
authors.affiliation: VA New England Mental Illness Research, Education and Clinical Center, West Haven, CT 06516, USA; Yale Medical School, New Haven, CT 06511, USA. Electronic address: elina.stefanovics@yale.edu.
authors.forename: Elina A
authors.initials: EA
authors.lastname: Stefanovics
authors.affiliation: VA New England Mental Illness Research, Education and Clinical Center, West Haven, CT 06516, USA; Yale Medical School, New Haven, CT 06511, USA; Clinical Neuroscience Division, Department of Veterans Affairs National Center for PTSD, VA Connecticut Healthcare System, West Haven, CT, USA.
authors.forename: John H
authors.initials: JH
authors.lastname: Krystal
authors.affiliation: VA New England Mental Illness Research, Education and Clinical Center, West Haven, CT 06516, USA; Yale Medical School, New Haven, CT 06511, USA; Psychiatry Service, VA Connecticut Healthcare System, West Haven, CT, USA.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Rosenheck
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014150:Antipsychotic Agents / Q000627:therapeutic use; D002908:Chronic Disease; D003130:Combat Disorders / Q000175:diagnosis* / Q000188:drug therapy / Q000523:psychology*; D003937:Diagnosis, Differential; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011569:Psychiatric Status Rating Scales / Q000706:statistics & numerical data*; D011594:Psychometrics / Q000706:statistics & numerical data; D018967:Risperidone / Q000627:therapeutic use; D012559:Schizophrenia / Q000175:diagnosis* / Q000188:drug therapy; D012565:Schizophrenic Psychology; D013313:Stress Disorders, Post-Traumatic / Q000175:diagnosis* / Q000188:drug therapy / Q000523:psychology*; D014728:Veterans / Q000523:psychology*; D055815:Young Adult
chemical_list: D014150:Antipsychotic Agents; D018967:Risperidone