Validation of the Turkish version of the Revised Foot Function Index for patients with foot and ankle disorders

Abstract

Background: The revised Foot Function Index (FFI-R) is a multidimensional instrument that was developed to assess a patient's self-reported health-related foot function. The FFI-R is clinically useful and easy to apply, and it has comprehensive subscales assessing the pain, stiffness, psychosocial stress, disability, and activity limitations related to foot and ankle problems. The present study was conducted to validate the Turkish version of the FFI-R, and to demonstrate its use in a Turkish population with various foot and ankle problems. Methods: The English version of the FFI-R was translated into Turkish, and then, it was administered to 124 patients (mean age of 39.9 years old) with foot and ankle problems and a mean symptom duration of 7.9 months. These patients completed two well-established foot and ankle-specific patient-reported outcome measures, the Foot and Ankle Outcome Score (FAOS) and the Manchester-Oxford Foot Questionnaire (MOX-FQ), and a general instrument, the 36-item Short Form Health Survey (SF-36). The test-retest reliability was evaluated using the intraclass correlation coefficient, and the internal consistency was measured using Cronbach's alpha. The construct validity of the FFI-R was assessed by correlating its subscales with the FAOS, MOX-FQ, and SF-36 subscales. Results: The test-retest reliability of the FFI-R ranged between 0.84 and 0.97. The internal consistency was 0.97 for the overall FFI-R, and it ranged between 0.85 and 0.97 for the subscales. Significant correlations were obtained between the FFI-R subscales and the FAOS, MOX-FQ, and SF-36 subscales. Conclusions: The Turkish version of the FFI-R was found to be a reliable and valid instrument for measuring the foot and ankle-related functional disability and health status of Turkish patients with foot and ankle problems. © 2019