Cross-cultural adaptation, reliability, and content validity of the Brief Negative Symptom Scale (BNSS) for use in Brazil

Abstract

Background: The Brief Negative Symptom Scale (BNSS) assesses the presence and intensity of negative symptoms in schizophrenia. Objectives: This study aimed to carry out the BNSS cross-cultural adaptation to the Brazilian Portuguese language and verify its content validity and reliability. Methods: This is a methodological study that followed these steps: (1) implementation of the cross-cultural adaptation and translation protocol, (2) BNSS adapted content validation, and (3) reliability assessment. Six experts participated in the adaptation process. The sample consisted of 30 individuals diagnosed with schizophrenia and assisted at the Brazilian Psychosocial Care Center (CAPS), in João Pessoa, Paraíba, Brazil, which was the research setting. Results: The cross-cultural adaptation was successful due to the values obtained for each aspect evaluated, such as semantic (0.922), idiomatic (0.910), experiential (0.961), and conceptual equivalence (0.974). The same happened with content validity regarding clarity of language (0.935), practical relevance (0.974), and theoretical relevance (0.948). Cronbach's alpha coefficient was 0.884 for the entire instrument, and the items ranged from 0.865 to 0.882. Discussion: The BNSS adaptation process has shown to be satisfactory for use in the Brazilian context, constituting a useful clinical tool for teaching and research.

The European Portuguese Version of the Brief Negative Symptom Scale

“…While our Cronbach's alpha was 0.91, the Spanish study [13] found one of 0.98 and the Brazilian studies found 0.94 [11] and 0.88 [12]. Our sample size was surpassed by only one of these three studies that collected 111 patients [11], while the Spanish including 20 [13] and another Brazilian including 30 patients [12]. In sum, our findings confirm the cross-cultural properties of BNSS and extend previous validations in Brazilian Portuguese and Spanish cultures to European Portuguese.…”

“…When comparing our validation findings with the BNSS validation findings in samples closely related to European Portuguese, culturally and linguistically, such as the existing studies with a Spanish sample [13] and Brazilian patients [11,12], we found similar consistency metrics. While our Cronbach's alpha was 0.91, the Spanish study [13] found one of 0.98 and the Brazilian studies found 0.94 [11] and 0.88 [12]. Our sample size was surpassed by only one of these three studies that collected 111 patients [11], while the Spanish including 20 [13] and another Brazilian including 30 patients [12].…”

“…To our knowledge, the BNSS has not been assessed in a European Portuguese sample. We found two translation studies in Brazilian samples [11, 12] and one in a Spanish [13] sample, which are the closest to European Portuguese, in terms of culture and language. Despite being the same language, the Brazilian Portuguese variety has substantial differences from European Portuguese, such as in: 1) grammar (for example, the frequent use of the gerund tense in Brazil) and 2) vocabulary (several words and expressions are not commonly used in one on the varieties or are so but have a different meaning (for example, in one question evaluating item 3 under anhedonia: “Existe alguma atividade que você fica na expectativa para fazer?” [Brazilian version] vs. “Haverá algo mais que o deixe entusiasmado por vir a realizar?” [Portuguese version]).…”

EPA guidance on assessment of negative symptoms in schizophrenia

“…BNSS was designed for easy application in the context of clinical trials or clinical routines and has excellent psychometric properties in schizophrenia [28,113] and in bipolar disorders (76). It has been translated and validated into 29 languages [141], notably Danish [142], Polish [143], German [144], Brazilian [68,145], and Spanish [146]. Nine translations were used in a European validation study [74].…”