Translation, cross-cultural adaptation and validation of the Upper Limb Functional Index (ULFI) into Brazilian Portuguese in patients with chronic upper limb musculoskeletal disorders.

Objective: The purpose of this study was to translate, cross-culturally adapt, and validate the Upper Limb Functional Index (ULFI) into Brazilian Portuguese (ULFI-Br).

Methods: The translation and cross-cultural adaptation of the ULFI was performed according to international recommendations. The ULFI-Br was applied to 190 patients with chronic upper limb musculoskeletal disorders to verify structural validity. The QuickDASH, the SF-36 and a Numerical Pain Scale (NPS) were completed by 180 patients to assess construct validity using the Spearman correlation (ρ). The internal structure of the ULFI-Br was evaluated by exploratory and confirmatory factor analysis with fit indices chi-square/degrees of freedom (DF), Root Mean Square Error of Approximation (RMSEA), Comparative Fit Index (CFI) and Tucker Lewis Index (TLI). A subsample of 51 patients was used to assess test-retest reliability using the intra-class correlation coefficient (ICC), standard error of measurement (SEM) and minimum detectable change at the 90th percentile (MDC). Internal consistency was assessed by Cronbach's alpha (α). Floor and ceiling effects were also assessed.

Results: Factor analysis identified an uni-dimensional structure with acceptable fit indices (RMSEA = 0.063, CFI = 0.918, TLI = 0.910). The ULFI-Br showed excellent reliability (ICC = 0.909) and adequate internal consistency (α = 0.897). The SEM was 6.11% and the MDC was 14.26%. The ULFI-Br demonstrated high correlation with the QuickDASH (ρ = -0.721), and moderate to low correlation with other questionnaires. There were no floor or ceiling effects.

Conclusion: The ULFI-Br showed adequate measurement properties in patients with chronic upper limb musculoskeletal disorders indicating its suitability for use as a measure of upper limb functional status in Brazil.