Analysis of the psychometric properties of the American Orthopaedic Foot and Ankle Society Score (AOFAS) in rheumatoid arthritis patients: application of the Rasch model.
OBJECTIVE
To tested the reliability and validity of Aofas in a sample of rheumatoid arthritis patients.


METHODS
The scale was applicable to rheumatoid arthritis patients, twice by the interviewer 1 and once by the interviewer 2. The Aofas was subjected to test-retest reliability analysis (with 20 Rheumatoid arthritis subjects). The psychometric properties were investigated using Rasch analysis on 33 Rheumatoid arthritis patients.


RESULTS
Intra-Class Correlation Coefficient (ICC) were (0.90<ICC<0.95; p<0.001) for intra-observer reliability and (0.75<ICC<0.91; p<0.001) for inter-observer reliability. Subjects separation rates were 1.9 and 4.75 for the items, showing that patients fell into three ability levels, and the items were divided into six difficulties levels. The Rasch analysis showed that eight items was satisfactory. One erroneous item have been identified, showing percentages above the 5% allowed by the statistical model. Further Rasch modeling suggested revising the original item 8.


CONCLUSIONS
The results suggest that the Brazilian versions of Aofas exhibit adequate reliability, construct validity, response stability. These findings indicate that Aofas Ankle-Hindfoot scale presents a significant potential for clinical applicability in individuals with rheumatoid arthritis. Other studies in populations with other characteristics are now underway.
Biofunction Department, Physical Therapy, Universidade Federal da Bahia, Salvador, BA, Brazil; Medicine and Health Program, Escola Bahiana de Medicina e Saúde Pública, Salvador, BA, Brazil. Electronic address: cristiano.sena@ufba.br.
Cristiano Sena da
CS
Conceição
Biofunction Department, Physical Therapy, Universidade Federal da Bahia, Salvador, BA, Brazil; Medicine and Health Program, Universidade Federal da Bahia, Salvador, Bahia, Brazil.
Mansueto Gomes
MG
Neto
Biofunction Department, Physical Therapy, Universidade Federal da Bahia, Salvador, BA, Brazil.
Anolino Costa
AC
Neto
Medicine and Health Program, Escola Bahiana de Medicina e Saúde Pública, Salvador, BA, Brazil.
Selena M D
SM
Mendes
Biointeraction Department, Universidade Federal da Bahia, Salvador, BA, Brazil.
Abrahão Fontes
AF
Baptista
Medicine and Health Program, Escola Bahiana de Medicina e Saúde Pública, Salvador, BA, Brazil.
Kátia Nunes
KN
Sá
D001172:Arthritis, Rheumatoid / Q000503:physiopathology*; D001938:Brazil; D006801:Humans; D009985:Orthopedics / Q000379:methods / Q000592:standards*; D011594:Psychometrics; D011788:Quality of Life; D015203:Reproducibility of Results; D018434:Sickness Impact Profile; D012955:Societies, Medical; D011795:Surveys and Questionnaires / Q000592:standards*; D014481:United States
Análise Rasch; Artrite reumatoide; Avaliação; Disability; Escala; Evaluation; Incapacidade; Rasch analysis; Rheumatoid arthritis; Scale