Validity, reliability, and Rasch analysis of the orthotics and prosthetics users' survey: Turkish version of the lower-extremity functional status

Abstract

Background: It is well known that questionnaires and scales are easy to use, cheap, and provide fast results. In the clinical setting, it will be easier and more comfortable to evaluate lower-extremity functions in both prosthesis and orthosis users with a single questionnaire. Objectives: To study the Turkish version of the orthotics and prosthetics users' survey lower-extremity functional status (OPUS-LEFS) and investigate its reliability and validity in the Turkish prosthesis and orthosis users. Study design: After forward and backward translation process, test–retest, internal consistency, validity, dimensionality, and Rasch analysis were done for 139 participants. Methods: Participants with a lower-limb prosthesis or orthosis were recruited in this study. Test and retest of the survey was done 1–3 days apart. For convergent validity, Nottingham Health Profile was used. Pearson correlation coefficient was used to analyze test–retest reliability; Cronbach's alpha for internal consistency, Spearman's correlation coefficient for validity, exploratory factor analysis by means of Kaiser–Meyer–Olkin and Bartlett's value of sphericity for dimensionality, and Rasch analysis were used. Results: Test–retest reliability of OPUS-LEFS showed very strong correlation (0.994) and for internal consistency with Cronbach's alpha value 0.71 of the Turkish version of OPUS-LEFS. Analyses showed that OPUS-LEFS is valid (p < 0.001) and significant (p < 0.001). Conclusions: The Turkish version of the OPUS-LEFS has been shown to be a valid and reliable tool in evaluating both orthosis and prosthesis users with a self-administered questionnaire for LEFS.