The Positive and Negative Symptoms Questionnaire: a self-report scale in schizophrenia

Abstract

The assessment of various symptoms in schizophrenia has received much interest, although few studies have compared evaluations by clinicians to those of their patients. Self-report tools may improve service delivery, data collection, and possibly also treatment adherence. We constructed the Positive and Negative Symptoms Questionnaire (PNS-Q), a self-report measure, after items from the Scale for Assessment of Positive Symptoms (SAPS) and the Scale for Assessment of Negative Symptoms (SANS). The PNS-Q contained 68 items and was administered to 61 schizophrenic inpatients. We examined its psychometric properties and utility as a self-report tool in schizophrenia. The PNS-Q exhibited high internal consistency for both its positive and negative subscales. External validity with the SAPS and SANS was low. The positive symptoms subscale correlated significantly with the SAPS ( r = .341, P < .01), whereas the negative symptoms subscale did not correlate at all with the SANS ( r = −0.086, P > .1). The correlation between patients' insight and scores of the PNS-Q was mixed. A partial correlation analysis failed to confirm a relationship between the rating of the patients' level of insight (measured by the Amador Scale to Assess Unawareness of Mental Disorders [SUMD]) and the disparity between the PNS-Q and the SAPS and SANS. However, the PNS-Q correlated highly with McEvoy's Vignettes, a measure of self-perception of symptoms. The results of this study are discussed in light of current research and methodologic issues. The PNS-Q reflects schizophrenics' self-perception, an important, yet neglected, aspect of schizophrenia. Using this new measure, we believe that clinicians and researchers will be able to gain insight to the inner world of these patients and improve their condition, as well as enhance patients' involvement in treatment planning.