The Brief Negative Symptom Scale (BNSS) was designed to address the main limitations of the existing scales for the assessment of negative symptoms in schizophrenia. The first validation of the scale by the same group involved in its development showed good convergent and discriminant validity, and a factor structure which confirmed the two domains of negative symptoms (reduced emotional/verbal expression and anhedonia/asociality/avolition). Nevertheless, the investigated samples of patients with schizophrenia were relatively small.

The present study aimed at providing a further independent validation of the BNSS in a large clinical sample to promote a wider diffusion of the scale in clinical research.

The inter-rater reliability, convergent/discriminant validity and factor structure of the Italian version of the BNSS were evaluated in 912 outpatients with schizophrenia recruited within an Italian multicenter study.

Our results confirmed the strong inter-rater reliability of the BNSS (the intraclass correlation coefficient ranged from 0.81 to 0.98 for individual items and was 0.98 for the total score). The convergent validity measures had r values from 0.62 to 0.77, while the divergent validity measures had r values from 0.20 to 0.28 in the whole sample (N=912) and in a smaller group of patients without clinically significant levels of depression and extrapyramidal symptoms (N=496). The BNSS factor structure was supported in both groups.

According to our results the BNSS is a promising measure for quantifying negative symptoms of schizophrenia in large multicenter clinical studies.

The study was carried out within the project 'Multicenter study on factors influencing real-life social functioning of people with a diagnosis of schizophrenia” of the Italian Network for Research on Psychoses.