European Validation of the Self-Evaluation of Negative Symptoms (SNS): A Large Multinational and Multicenter Study.

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: Significant positive correlations were observed between the total score of the SNS and the total scores of the PANSS negative subscale (r = 0.37; P < 0.0001) and the BNSS (r = 0.43; p < 0.0001). SNS scores did not correlate with the level of insight, parkinsonism, or the total score of the PANSS positive subscale. A positive correlation was found between SNS and CDSS (r = 0.35; p < 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.

Specificity and sensitivity of the Self-assessment of Negative Symptoms (SNS) in patients with schizophrenia.

OBJECTIVES: Negative symptoms can be present at any stage of schizophrenia but their evaluation remains challenging. Self-evaluations may be particularly useful in screening negative symptoms quickly and effectively. The purpose of this study was to determine the sensitivity, the specificity, and the threshold beyond which the negative symptoms are considered pathological in a comparative study between patients with schizophrenia and healthy subjects using the Self-assessment of Negative Symptoms (SNS). METHODS: One hundred and nine patients with schizophrenia and schizoaffective disorders (DSM-5) and 99 healthy controls were included and evaluated with the SNS. AUROC analyses were performed to assess the discriminant performance of the SNS scale for screening negative symptoms in the whole sample of patients but also in 2 patient sub-samples without high scores of depression or negative symptoms. RESULTS: The SNS (AUROC = 0.942 ±â€¯0.046; p < 0.001) appears to be an appropriate screening tool for distinguishing between SZ and HC with a threshold value of 7, and the sensitivity and specificity were 92.7% (95CI = [86.1-96.8]) and 85.9% (95CI = [77.4-92.1]) respectively. A threshold at 7 was also observed in the samples without patients with high level of depressive or negative symptoms. CONCLUSION: These results indicate that SNS might be a valuable tool for screening negative symptoms in clinical practice regardless the level of depressive and negative symptoms. Further studies using SNS in subjects at high risk for psychosis or with a first psychotic episode would be useful in the detection of negative symptoms.

A large European, multicenter, multinational validation study of the Brief Negative Symptom Scale.

Negative symptoms represent an unmet need of treatment in schizophrenia. Although a consensus exists on negative symptom construct, and second generation assessment instruments reflecting the consensus are available, studies still rely upon old assessment instruments, that do not reflect recent conceptualizations and might limit progress in the search for effective treatments. This is often the case in the European context, where one of the challenges encountered in designing large studies is the availability of validated instruments in the many languages of the continent. To address this challenge and promote sound research on negative symptoms in Europe, the ECNP Schizophrenia Network coordinated a large multicenter, multinational validation study of the Brief Negative Symptom Scale (BNSS). Clinically-stable subjects with schizophrenia (SCZ, N = 249) were recruited from 10 European Countries. Apart from BNSS, subjects were administered the Positive and Negative Syndrome Scale (PANSS) and standardized instruments for depression, extrapyramidal symptoms and psychosocial functioning. Results showed an excellent internal consistency, convergent and discriminant validity of BNSS and replicated a 5 factor-model. A larger number of subjects with predominant negative symptoms, i.e. the target population for clinical trials, was identified by using the BNSS compared to the PANSS. Regression analysis showed that BNSS-avolition, a key negative symptom poorly assessed by PANSS, explained 23.9% of psychosocial functioning, while no combination of the PANSS core negative symptoms showed the same impact on functioning. The study demonstrated that BNSS has substantial advantages with respect to PANSS for the identification of the avolition domain and subjects with predominant negative symptoms.