Revisiting the 5 dimensions of the Positive and Negative Syndrome Scale.
BACKGROUND
The Positive and Negative Syndrome Scale (PANSS) is a widely used instrument to measure severe psychopathology in schizophrenia. Recently, its widely accepted 5-factor solution is questioned using confirmatory factor analysis (CFA). This article examines the appropriateness of applying CFA to PANSS data and the dimensionality of the PANSS in a large sample of persons with chronic schizophrenia, schizophreniform disorder, and schizoaffective disorder.


METHODS
Data reduction was conducted on PANSS baseline assessments from 2 multicenter clinical trials consisting of 1284 persons' available PANSS data at baseline and Week 8. Supplementary analyses were conducted for separate trials and for noncompleters at baseline (n = 1872).


RESULTS
Examination of the data indicated that the statistical requirements of CFA (eg, multivariate normality) were not met by the data. Multidimensional scaling and a scree plot of principal components superimposed on simulated random data converged to indicate that 5 dimensions are generally a parsimonious fit to the PANSS at baseline, whereas 4 dimensions emerged after 8 weeks of treatment. The components included negative symptoms, positive symptoms, disorganized (baseline only), anxiety/depression, and excited.


CONCLUSIONS
The results demonstrate realistic alternatives to CFA when studying the PANSS, support a 5-component model of PANSS ratings at baseline, and indicate that the structure of symptoms change after 8 weeks of treatment. These results seem to be robust because they generally replicate within trials for completers and at baseline for the entire sample.
Levine
Stephen Z
SZ
Bar Ilan University, Ramat Gan, Israel. levins@biu.ac.il
Rabinowitz
Jonathan
J
D014150:Antipsychotic Agents / Q000627:therapeutic use*; D003198:Computer Simulation; D018849:Controlled Clinical Trials as Topic; D003627:Data Interpretation, Statistical; D005163:Factor Analysis, Statistical; D005260:Female; D006220:Haloperidol / Q000627:therapeutic use; D006801:Humans; D008297:Male; D011569:Psychiatric Status Rating Scales / Q000592:standards*; D011594:Psychometrics; D015203:Reproducibility of Results; D018967:Risperidone / Q000627:therapeutic use; D012559:Schizophrenia / Q000188:drug therapy*; D012565:Schizophrenic Psychology; D012720:Severity of Illness Index
D014150:Antipsychotic Agents; D006220:Haloperidol; D018967:Risperidone