Brief Negative Symptom Scale Reliably Assesses Negative Symptoms in Schizophrenia

The Brief Negative Symptom Scale (BNSS) is internally consistent and validated for the assessment of negative symptoms in patients with schizophrenia, according to a study published in Schizophrenia Research.

The investigators of this study sought to examine the reliability, validity, and factor structure of the BNSS in an Asian population, as well as to explore the association between BNSS assessment and functioning in patients with schizophrenia. The study included 274 English-speaking individuals with schizophrenia, aged 21 to 65 years, who were recruited from outpatient clinics at the Institute of Mental Health, Singapore. All participants were assessed using the BNSS, Positive and Negative Syndrome Scale (PANSS), Scale for the Assessment of Negative Symptoms (SANS), Global Assessment of Functioning Scale (GAF), Calgary Depression Scale for Schizophrenia (CDSS), and Simpson-Angus Extrapyramidal Side Effects Scale. The investigators examined the concurrent, discriminant, and construct validity of BNSS using Spearman’s correlation between BNSS and subscales of PANSS and SANS; factor structure of BNSS was explored through confirmatory factor analyses. After adjusting for covariates, the investigators conducted multiple regression analyses with GAF as the dependent variable and either BNSS Total, the 5 BNSS domains (anhedonia, asociality, avolition, blunted affect, and alogia), or the 2 BNSS factors (motivation-pleasure and emotional expressivity) as independent variables.

The total 13-item BNSS had good internal consistency when all items were included (Cronbach’s alpha=0.880) but was lower when any item was left out; BNSS subscale values ranged from 0.848 to 0.949. Spearman’s correlations between BNSS subscales and between BNSS and all other scales were high, supporting good validity claims. In confirmatory factor analyses, the 5 BNSS domains, or 5-factor model, fit the data better than the 2-factor model: However, a second-order model was superior to both in which anhedonia, asociality, and avolition were correlated with motivation-pleasure, and blunted affect and alogia were correlated with emotional expressivity. GAF functioning scores were significantly associated with negative symptoms assessed in BNSS Total (B=−0.438; P <.001), motivation-pleasure scores (B=−0.876; P <.001), asociality (B=−0.950; P =.001), and avolition (B=−2.503; P <.001).

One limitation to the study was including only outpatients who were relatively stable from a single community, which impacts the generalizability of results to a broader population with more severe symptoms. Additionally, the same rater assessed all scales, which could result in higher correlations, and cross-sectional data could not be tested or retested for reliability.

BNSS assessment of negative symptoms was best calculated using a 5-factor or second-order model, and negative symptoms of motivation-pleasure, avolition, and asociality were significantly associated with functioning. The investigators suggested that the BNSS had good internal consistency and validity and supported the reliable use of BNSS in clinical practice.

Reference

Ang MS, Rekhi G, Lee J. Validation of the brief negative symptom scale and its association with functioning [published online April 13, 2019]. Schizophr Res. doi: 10.1016/j.schres.2019.04.005