Purpose: To validate the Lithuanian version of the Self-Evaluation Negative Symptoms Scale (Lith-SNS).
Materials and methods: A double translation from French to Lithuanian and back was performed. We included patients from in-patient and out-patient settings that had a diagnosis of paranoid schizophrenia according to ICD-10 criteria and were screened as free from acute psychotic symptoms using the Mini International Neuropsychiatric Interview (MINI). Participants were evaluated using the Brief Psychiatric Rating Scale (BRPS) and completed the Lith-SNS scale. We measured internal consistency, convergent validity, and discriminant validity of Lith - SNS comparing its scores with BPRS negative and positive symptom subscores.
Results: A total of 67 participants were evaluated. Cronbach's alpha (α) for all 20 items of Lith-SNS (α = 0.82), and for the five subscores (α = 0.76) showed good internal consistency. Factor analysis showed a 2-factor solution which accounted for 70.12% of the variance with the first factor accounting for 53.3% and the second factor accounting for 16.8% of the variance. Lith-SNS total scores and all five subscores significantly correlated with BPRS negative symptoms subscores showing good convergent validity. There was a correlation between the Positive subscore of BPRS and the alogia subscore of Lith-SNS (r = 0.39, p = 0.001), but no correlations with other subscores or the total Lith-SNS score showing adequate discriminant validity.
Conclusions: Lithuanian version of SNS is a valuable tool to evaluate negative symptoms of schizophrenia with good internal consistency, convergent, and discriminant validity.
Keywords: SNS; Schizophrenia; negative symptoms; self-evaluation.