Content validity and responsiveness of a Finnish version of the Patient-Specific Functional Scale

Abstract

Background: The Patient-Specific Functional Scale (PSFS) questionnaire was developed by Stratford and colleagues to provide a method for eliciting, measuring and recording descriptions of patients’ disabilities. It can be used to guide treatment and assess patient outcome. The aim of the study was to translate and validate a Finnish version of the internationally used PSFS questionnaire, by testing its content validity and responsiveness, and to conduct a cross-cultural adaptation of the measure. Methods: The final version of the Finnish questionnaire underwent a cross-cultural adaptation before the validation study. The subjects of the study were patients receiving physiotherapy for low back pain (n = 78). They completed the PSFS questionnaire prior to physiotherapy treatment and after treatment series. Roland–Morris Disability Questionnaire (RMDQ) and the visual analogue scale (VAS) were recorded before and after the treatment series. Results: For content validity, a good correlation of the scores between baseline measures of PSFS and RMDQ were 0.65 (Pearson's rho) (p < 0.01). For responsiveness, moderate to good correlation among the measures between changes of the PSFS, RMDQ and VAS (0–100 mm) scores were analysed. Conclusions: The Finnish translation of the PSFS questionnaire performs as the original, is proven to have adequate content validity and responsiveness, and could be recommended as an assessment tool for clinical and research use.