Background and Objectives: Prevalence data of different classes of negative symptoms in an inpatient setting are scarce. Most of the data are collected in clinical trials under strict inclusion criteria, using older psychometric scales with known content validity flaws. The objectives of this study were to report the prevalence of different classes of negative symptoms in a naturalistic inpatient setting using both older and newer psychometric scales and to determine whether second-generation psychometric scales were not inferior to older scales in detecting negative symptoms. Materials and Methods: Negative symptoms were evaluated using older-generation (Positive and Negative Symptoms Scale, PANSS) and second-generation (Brief Negative Symptoms Scale, BNSS, and Self-Evaluation of Negative Symptoms Scale, SNS) measures. Primary, prominent, core, and predominant negative symptoms were calculated according to various descriptions used in other studies. Results: A total of 323 participants were included in this study. The mean score of the PANSS negative symptoms subscores was 25.33 (SD = 6.86, 95% CI 24.57–26.09), the mean total BNSS score was 36.48 (SD = 15.93, 95% CI 34.74–38.23), and the mean SNS total score was 18,9 (SD = 8.99, 95% CI 17.91–19.89). The prevalence of primary negative symptoms was similar in all groups. PANSS and BNSS categorized 71% of the sample as having prominent negative symptoms. The average prevalence of predominant negative symptoms, as measured by PANSS and BNSS, was 9.6%, whereas SNS reported 10.5%. Conclusions: Negative symptoms were highly prevalent in our inpatient sample. Most of our participants had primary and prominent negative symptoms; however, only a small fraction met the criteria for predominant negative symptoms. Prevalence data were similar between PANSS, BNSS, and SNS, showing that BNSS and SNS are not inferior to PANSS.

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