Psychometric Evaluation of the Persian Version of the Functional Mobility Scale: Assessing Validity and Reliability

Abstract

Aim This study aimed to assess the content, concurrent validity, test-retest, and intra-rater reliability of the Persian version of the Functional Mobility Scale (FMS) for evaluating functional mobility in children and adolescents with cerebral palsy (CP). Methods Following international standards for measurement translation, we developed a Persian version of the FMS. A total of 160 participants took part in this study. Concurrent validity was assessed using Spearman’s coefficient to correlate with the Gross Motor Function Classification System (GMFCS). Test-retest (n = 30) and intra-rater (n = 30) reliability of the FMS were also examined by Cohen’s weighted kappa coefficient. Results Concurrent validity ranged from −0.912 to −0.941 for children and −0.912 to −0.936 for adolescents. Test-retest ranged from 0.902 to 1. Intra-rater ranged from 0.933 to 0.987. Conclusion The Persian version of the FMS demonstrates very strong validity and almost perfect reliability for assessing and classifying functional mobility in children and adolescents with CP. These findings suggest that this tool could be a useful addition to clinical practice and research for the Persian-speaking population.