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.

Self-Evaluation of Negative Symptoms: A Novel Tool to Assess Negative Symptoms.

Many patients with schizophrenia have negative symptoms, but their evaluation is a challenge. Thus, standardized assessments are needed to facilitate identification of these symptoms. Many tools have been developed, but most are based on observer ratings. Self-evaluation can provide an additional outcome measure and allow patients to be more engaged in their treatment. The aim of this study was to present a novel tool, Self-evaluation of Negative Symptoms (SNS), and demonstrate its validity. Forty-nine patients with schizophrenia and schizoaffective disorders according to DSM-5 were evaluated. Cronbach's coefficient (α = 0.867) showed good internal consistency. Factor analysis extracted 2 factors (apathy and emotional) that accounted for 75.2% of the variance. The SNS significantly correlated with the Scale of Assessment of Negative Symptoms (r= 0.628) and the Clinician Global Impression on the severity of negative symptoms (r= 0.599), supporting good convergent validity. SNS scores did not correlate with level of insight (r= 0.008), Parkinsonism (r= 0.175) or Brief Psychiatric Rating Scale positive subscores (r= 0.253), which indicates good discriminant validity. The intrasubject reliability of the SNS revealed excellent intraclass correlation coefficients (ICC = 0.942). Taken together, the results show that the SNS has good psychometric properties and satisfactory acceptance by patients. The study also demonstrates the ability of patients with schizophrenia to accurately report their own experiences. Self-assessments of negative symptoms should be more widely employed in clinical practice because they may allow patients with schizophrenia to develop appropriate coping strategies.