Structural validity of the Brazilian version of the Western Ontario and McMaster Universities Osteoarthritis Index among patients with knee osteoarthritis

• Autor(a) principal: Ferreira,Cheila de Sousa Bacelar
• Data de Publicação: 2020
• Outros Autores: Dibai-Filho,Almir Vieira, Almeida,Davi Oliveira da Silva, Bassi-Dibai,Daniela, Barreto,Felipe Souza, Oliveira,Adriano Rodrigues de, Fidelis-de-Paula-Gomes,Cid André
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: São Paulo medical journal (Online)
• Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S1516-31802020000500400
• topic: Reproducibility of results; Surveys and questionnaires; Pain; Rheumatology; Joint degeneration; Exploratory factor analysis; Confirmatory factor analysis; WOMAC

BACKGROUND: The original structure of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) has been contested in several languages. OBJECTIVE: To assess the structural validity of the Brazilian version of WOMAC among patients with knee osteoarthritis. DESIGN AND SETTING: Structural validity study conducted at physiotherapy clinics and primary healthcare units. METHODS: The study included males and females aged 40 to 80 years who were all native Brazilian Portuguese speakers, with knee pain in the previous six months and a diagnosis of knee osteoarthritis. We used exploratory factor analysis (EFA) followed by confirmatory factor analysis (CFA) with implementation of a polychoric matrix and the robust diagonally weighted least squares (RDWLS) extraction method. The adequacy of the model was assessed using the following fit indices: root mean square error of approximation (RMSEA), comparative fit index (CFI), Tucker-Lewis index (TLI), standardized root mean square residual (SRMR) and chi-square/degree of freedom (DF). RESULTS: 203 patients with knee osteoarthritis were included. The model proposed in this study with two factors, i.e. “pain” (items 1, 2, 3 and 4) and “physical function” (items 10, 11, 16, 17, 18, 19, 21 and 22), showed adequate fit indices in CFA: chi-square/DF = 1.30; CFI = 0.976; TLI = 0.970; RMSEA = 0.039; and SRMR = 0.070. The factorial loads ranged from 0.68 to 0.76 for the “pain” domain and 0.44 to 0.62 for the “physical function” domain. CONCLUSION: The Brazilian version of WOMAC with two domains, i.e. “pain” (four items) and “physical function” (eight items), presents the best structure.