Stability of the five-factor structure of the Positive and Negative Syndrome Scale (PANSS).

The main objective of the study was to verify the stability of the five-factor (negative. positive, excitation, depression and cognitive) structure of the Positive and Negative Syndrome Scale (PANSS). The psychometric properties (validity and reliability) of the forced five-factor structure of the PANSS were explored in two different populations of schizophrenic patients: one in relapse and the other in the chronic phase of the disease. Three hundred and forty-two schizophrenic patients according to DSM-III-R criteria were involved. One hundred and eighteen (34.5%) patients were in relapse, and 224 (65.5%) were in the chronic phase. The forced five-factor principal-component analysis explained 64.3% of the total variance in the relapse patients and 62.1% in the chronic patients. The order of the factors was reversed for the depression and excitation factors in chronic patients compared with patients in relapse. The internal consistency of this five-factor structure was good (Cronbach's alpha >0.70) in the relapse and chronic patients, except for the cognitive factor. In conclusion. five dimensions (negative, positive, excitation, depression and cognition) are necessary to account for the various clinical aspects of schizophrenia described by PANSS in relapse and chronic schizophrenic patients.