Validation of the Simple Shoulder Test in a Portuguese-Brazilian Population. Is the Latent Variable Structure and Validation of the Simple Shoulder Test Stable across Cultures?

BACKGROUND: The validation of widely used scales facilitates the comparison across international patient samples. The objective of this study was to translate, culturally adapt and validate the Simple Shoulder Test into Brazilian Portuguese. Also we test the stability of factor analysis across different cultures. OBJECTIVE: The objective of this study was to translate, culturally adapt and validate the Simple Shoulder Test into Brazilian Portuguese. Also we test the stability of factor analysis across different cultures. METHODS: The Simple Shoulder Test was translated from English into Brazilian Portuguese, translated back into English, and evaluated for accuracy by an expert committee. It was then administered to 100 patients with shoulder conditions. Psychometric properties were analyzed including factor analysis, internal reliability, test-retest reliability at seven days, and construct validity in relation to the Short Form 36 health survey (SF-36). RESULTS: Factor analysis demonstrated a three factor solution. Cronbach’s alpha was 0.82. Test-retest reliability index as measured by intra-class correlation coefficient (ICC) was 0.84. Associations were observed in the hypothesized direction with all subscales of SF-36 questionnaire. CONCLUSION: The Simple Shoulder Test translation and cultural adaptation to Brazilian-Portuguese demonstrated adequate factor structure, internal reliability, and validity, ultimately allowing for its use in the comparison with international patient samples.