Cross-cultural adaptation of the Patient Specific Functional Scale 2.0 into Japanese

Abstract

The patient-specific functional scale (PSFS) is a patient-reported outcome measure of disability that has high responsiveness and can be adapted to a variety of musculoskeletal disorders. It is often difficult for patients to recall the activities to rate and their pre-disability status on the PSFS, and the PSFS 2.0 has recently been developed to make it easier for respondents to answer. The purpose of this study was the cross-cultural adaptation of the PSFS 2.0 into Japanese. Following an international guideline for cross-cultural adaptation of patient-reported outcome measures, the adaptation was conducted through the following five steps: forward-translation, creation of an integrated version, backward-translation, creation of a provisional Japanese version, and pilot testing. In the pilot testing, 30 Japanese participants with musculoskeletal disorders rated each sentence on a 5-point numerical rating scale (from 1: I don't understand the meaning of the sentence at all, to 5: I can understand the sentence sufficiently), and comments were obtained. In sentences that were commented upon, ≥ 80% of the participants posted a score of ≥4. Based on the comments obtained, the final Japanese version of the PSFS 2.0 was developed via discussions among all six members of its translators and authors.