European Validation of the Self-Evaluation of Negative Symptoms (SNS): A Large Multinational and Multicenter Study
Sonia Dollfus, Armida Mucci, Giulia Maria Giordano, István Bitter, Stephen F. Austin, Camille Delouche, Andreas Erfurth, W. Wolfgang Fleischhacker, Larisa Movina, Birte Glenthøj, Karoline Gütter, Alex Hofer, Jan Hubeňák, Stefan Kaiser, Jan Libiger, Ingrid Melle, Mette Ødegaard Nielsen, Oleg Papsuev, Janusz Rybakowski, Gabriele Sachs, Alp Üçok, Francesco Brando, Paweł Wójciak, Silvana Galderisi
Abstract
BACKGROUND: Negative symptoms are usually evaluated with scales based on observer ratings and up to now self-assessments have been overlooked. The aim of this paper was to validate the Self-evaluation of Negative Symptoms (SNS) in a large European sample coming from 12 countries. We wanted to demonstrate: (1) good convergent and divergent validities; (2) relationships between SNS scores and patients' functional outcome; (3) the capacity of the SNS compared to the Brief Negative Symptom Scale (BNSS) to detect negative symptoms; and (4) a five-domain construct in relation to the 5 consensus domains (social withdrawal, anhedonia, alogia, avolition, blunted affect) as the best latent structure of SNS. METHODS: Two hundred forty-five subjects with a DSM-IV diagnosis of schizophrenia completed the SNS, the Positive and Negative Syndrome Scale (PANSS), the BNSS, the Calgary Depression Scale for Schizophrenia (CDSS), and the Personal and Social Performance (PSP) scale. Spearman's Rho correlations, confirmatory factor analysis investigating 4 models of the latent structure of SNS and stepwise multiple regression were performed. RESULTS: < 0.0001). Among the 5 SNS subscores, only avolition subscores entered the regression equation explaining a lower functional outcome. The 1-factor and 2-factor models provided poor fit, while the 5-factor model and the hierarchical model provided the best fit, with a small advantage of the 5-factor model. The frequency of each negative dimension was systematically higher using the BNSS and the SNS vs. the PANSS and was higher for alogia and avolition using SNS vs. BNSS. CONCLUSION: In a large European multicentric sample, this study demonstrated that the SNS has: (1) good psychometric properties with good convergent and divergent validities; (2) a five-factor latent structure; (3) an association with patients' functional outcome; and (4) the capacity to identify subjects with negative symptoms that is close to the BNSS and superior to the PANSS negative subscale.