Cross-Cultural Adaptation and Validation of the German Version of the Upper Limb Functional Index

Abstract

Context: The Upper Limb Functional Index (ULFI) is a popular tool with valid psychometric properties to assess upper limb function in patients with musculoskeletal conditions. The aim of the study was to cross-culturally adapt and validate the German version of the ULFI. Design: Cross-cultural validation. Methods: A 2-stage cross-cultural adaptation of the ULFI was performed according to international guidelines through consecutive forward and backward translations. Psychometric properties of internal consistency, test–retest reliability, criterion, face and content validity, and factor structure were determined from the included German participants suffering from upper limb conditions (n = 100), who fulfilled the following inclusion criteria: (1) older than 18 years old, (2) German as native language, and (3) medical diagnosis of musculoskeletal upper limb condition. Participants completed the ULFI; Disabilities of the Arm, Shoulder, and Hand; EuroQol Health Questionnaire 5 Dimensions; and Short Form-12 questionnaires. Results: The ULFI-G showed good internal consistency (α = .88); excellent test–retest reliability (intraclass correlation coefficient2:1 = .98); directly strong correlation with Disabilities of the Arm, Shoulder, and Hand (r = .84); fair correlation with Disabilities of the Arm, Shoulder, and Hand-sport (r = .54); inversely fair correlation with EuroQol Health Questionnaire 5 Dimensions (r = −.62); and Short Form 12’s physical health domain (r = −.7). A single-factor structure was revealed. Conclusions: The ULFI-G showed adequate psychometric properties and proved to be a valid tool for upper limb functional assessment in German population.