Cross-cultural adaptation and validation of the Brazilian-Portuguese version of the Bath Ankylosing Spondylitis Functional Index (BASFI).

OBJECTIVE: To conduct a cross-cultural adaptation of the Bath Ankylosing Spondylitis Functional Index (BASFI) into Brazilian-Portuguese language and to assess its measurement properties. METHODS: The BASFI was translated by four rheumatologists and three English teachers. The translated questionnaire was applied to ankylosing spondylitis patients by trained observers, and self-administered in three moments: days 1, 2, and 14. The validity was assessed analyzing the association of BASFI and functional capacity measures (cervical rotation, intermalleolar distance, Schober's test and occiput-to-wall distance). The internal consistence was tested by Cronbach's α coefficient and the reliability by test-retest (intraclass correlation coefficient - ICC). RESULTS: A total of 60 patients with ankylosing spondylitis was included: 85% male, mean age 47 ± 12 years, and mean disease duration 20 ± 11 years. The intra-observer test-retest (two-week interval) reliability showed a high ICC (0.999, 95% CI: 0.997-0.999) and a high internal consistency (Cronbach's α coefficient: 0.86, CI 95%: 0.80-0.90). Considering the validity, the BASFI indices were correlated with cervical rotation (0.53, P < 0.001) and with intermalleolar distance (0.50, P < 0.001). CONCLUSION: The BASFI Brazilian-Portuguese version is reliable and valid for assessment of patients with ankylosing spondylitis.

Adaptação cultural cruzada e validação da versão do Índice Funcional de Espondilite Anquilosante de Bath (BASFI) para o português do Brasil / Cross-cultural adaptation and validation of the Brazilian-Portuguese version of the Bath Ankylosing Spondylitis Functional Index (BASFI)

OBJETIVO: Conduzir uma adaptação cultural cruzada do Índice Funcional de Espondilite Anquilosante de Bath (BASFI, Bath Ankylosing Spondylitis Functional Index) para o português do Brasil e avaliar suas propriedades de medição. MéTODOS: O BASFI foi traduzido por quatro reumatologistas e três professores de língua inglesa. O questionário traduzido foi aplicado a pacientes com espondilite anquilosante por observadores treinados e autoaplicado em três momentos, dias 1, 2 e 14. A validade foi estimada analisando-se a associação do BASFI e as medidas de capacidade funcional (rotação cervical, distância intermaleolar, teste de Schober e distância occipito-parede). A consistência interna foi testada pelo coeficiente α de Cronbach, e a confiabilidade pelo teste-reteste (coeficiente de correlação intraclasse [CCI]). RESULTADOS: Foram incluídos 60 pacientes com espondilite anquilosante: 85% do gênero masculino, com idade média de 47 ± 12 anos e duração média da doença de 20 ± 11 anos. A confiabilidade intraobservador no teste-reteste (intervalo de duas semanas) revelou alto ICC (0,999; 95% IC: 0,997-0,999), além de alta consistência interna (coeficiente α de Cronbach: 0,86; 95% IC: 0,80-0,90). Considerando-se a validade, os índices do BASFI foram correlacionados com a rotação cervical (0,53; P < 0,001) e a distância intermaleolar (0,50; P < 0,001). CONCLUSÃO: A versão do BASFI para o português do Brasil é confiável e válida para avaliação de pacientes com espondilite anquilosante.

OBJECTIVE: To conduct a cross-cultural adaptation of the Bath Ankylosing Spondylitis Functional Index (BASFI) into Brazilian-Portuguese language and to assess its measurement properties. METHODS: The BASFI was translated by four rheumatologists and three English teachers. The translated questionnaire was applied to ankylosing spondylitis patients by trained observers, and self-administered in three moments: days 1, 2, and 14. The validity was assessed analyzing the association of BASFI and functional capacity measures (cervical rotation, intermalleolar distance, Schober's test and occiput-to-wall distance). The internal consistence was tested by Cronbach's αcoefficient and the reliability by testretest (intraclass correlation coefficient - ICC). RESULTS: A total of 60 patients with ankylosing spondylitis was included: 85% male, mean age 47 ± 12 years, and mean disease duration 20 ± 11 years. The intra-observer test-retest (two-week interval) reliability showed a high ICC (0.999, 95% CI: 0.997-0.999) and a high internal consistency (Cronbach's α coefficient: 0.86, CI 95%: 0.80-0.90). Considering the validity, the BASFI indices were correlated with cervical rotation (0.53, P < 0.001) and with intermalleolar distance (0.50, P < 0.001). CONCLUSION: The BASFI Brazilian-Portuguese version is reliable and valid for assessment of patients with ankylosing spondylitis.