Validation of the Lithuanian version of the brief Negative Symptoms Scale.

Purpose of the article: To validate the Lithuanian version of the Brief Negative Symptoms Scale (Lith-BNSS) in a Lithuanian speaking sample.

Materials and methods: We performed a double translation of BNSS from English into Lithuanian. Four clinicians conducted psychometric validation. We checked the internal consistency of the 13 items and six subscales of BNSS. Convergent and discriminant validity were calculated by applying BNSS in clinical practice with other psychometric tools for negative, positive, and depressive symptoms and cognitive deficit assessment. The psychometric tools used were BNNS, Self-assessment of Negative Symptoms Scale (SNS), Positive and Negative Symptoms Scale (PANSS), Montgomery Asberg Depression Rating Scale (MADRS), and Calgary Depression Scale for Schizophrenia (CDSS). We calculated the convergent and discriminant validities using Pearson and Spearman correlations.

Results: We have included 130 patients. Excellent internal consistency was observed for the 13 items (alpha = 0.944) and the six subscales (alpha = 0.874) of BNSS. Good convergent validity is illustrated by strong Pearsons's correlations with the PANSS negative subscale (r = 0.77, p < 0.001) and the PANSS Marder negative factor (r = 0.77, p < 0.001). Adequate discriminant validity is shown by a non-significant correlation with PANSS positive subscore (r = 0.13, p = 0.15), PANSS Marder positive factor (r = 0.14, p = 0.13), CDSS total score (r = 0.02, p = 0.83) and MADRS total score (r = 0.12, p = 0.2).

Conclusions: Lith-BNSS has good psychometric properties and can be used as a valuable addition to the available Lithuanian evaluation tools for negative symptoms of schizophrenia.