Cross-Cultural Adaptation and Measurement Properties of the Upper Limb Functional Index (ULFI) for Greek-Speaking Patients

Introduction: The upper limb functional index (ULFI) is a widely used outcome measure for patients with upper limb musculoskeletal disorders (ULMSDs) that is available in several languages. Our purpose was to develop the Greek version of the ULFI and test its test-retest reliability, validity, and responsiveness in a cohort of patients with ULMSD. Methods: We used a merged methodology of published guidelines and recommendations for the translation and cross-cultural adaptation process. One hundred patients with ULMSDs completed the ULFI-Gr on three occasions: baseline, 2-7 days later to evaluate repeatability, and 6 weeks later to assess responsiveness. Participants completed the quick disability of the arm, shoulder, and hand questionnaire (Quick-DASH) and a numerical pain rating scale (NPRS) to evaluate convergent validity. Also, a global rating of change (GROC) scale was used to evaluate responsiveness. Results: Minor wording adaptations were required during the translation and cross-cultural adaption of the questionnaire. Factor analysis resulted in two main factors explaining 40.2% of the total variance. The ULFI-Gr was found to be reliable (intraclass correlation coefficient: 0.97, 95% confidence interval: 0.95-0.99) with a small measurement error (standard error of measurement: 3.34%, minimal detectable change: 7.79%). The ULFI-Gr showed a strong negative correlation with the Quick-DASH (-0.75), a moderate to strong negative correlation with the NPRS (-0.56), and a good level of responsiveness (standardized response mean: 1.31, effect size: 1.19). Conclusions: The ULFI-Gr can be used as a reliable, valid, and responsive patient-reported outcome measure to evaluate the functional status of patients with ULMSDs.