Cross-Cultural Adaptation and Psychometric Testing of the Lower Extremity Functional Scale to Urdu Language

Abstract

The standardization of outcome measurements across studies, conducted in various contexts, is facilitated by the cross-cultural adaptation of questionnaires. It is advised that the procedure should adhere to the standardized methods. In addition to addressing cultural and linguistic issues, the psychometric features of the modified version should be investigated. The purpose of this study was to translate and culturally adapt the Lower Extremity Functional Scale (LEFS) into Urdu and evaluate the reliability, validity, and responsiveness of the Urdu version of the Lower Extremity Functional Scale (LEFS-U. The original version of LEFS was translated and cross-culturally adapted using established worldwide standards. All the participants underwent baseline administration of LEFS-U, 36-item Short Form Health Survey (SF-36), Visual Analogue Scale for Pain (VAS-pain), and Visual Analogue Scale for Disability (VAS-disability), followed by a second administration to the patients’ group after receiving 3 weeks of the intervention. The Global Rate of Change Scale (GROC) was also administered at that time. Furthermore, factor analysis, reliability, validity, and responsiveness of LEFS-U, all were assessed. The LEFS was found internally consistent with Cronbach’s alpha of 0.99 and excellent test re-test reliability, evaluated by Intraclass correlation coefficient (ICC) was 0.98 (95% CI: 0.96-0.99). The LEFS-U has a one-factorial structure, which constitutes 67.85% of the total variance. A significant difference in LEFS-U total score was found between patients and healthy controls (p<0.001). Moreover, Pearson’s correlation coefficient showed a moderate correlation between LEFS-U and SF-36 Physical Function (0.54), Role Physical (0.58), Body Pain (0.61), VAS-pain (-0.50), and VAS-disability (-0.45). The results show that LEFS-U is a reliable, valid, and responsive questionnaire to measure disability in patients with lower extremity disorders.