Cross-cultural Adaption and Validity of the “Patient Specific Functional Scale” / Kulturelle Adaption und Validierung der deutschen Version der “Patient Specific Functional Scale”

Abstract Objective: Measurement of activity and participation related outcomes play an important role in rehabilitation of low back pain. Therefore the „Patient Specific Functional Scale»(PSFS) was developed to assess individual, patient related activities. The aim of this study is the cultural adaptation and validation of the PSFS for German speaking countries. Method: A cultural translation and adaptation process was carried out in accordance with standardized guidelines. The internal and external responsiveness and the construct validity adjustment to the German version pertaining to patients with lumbar back pain was examined in comparison to the «Oswestry Disability Index»(ODI). Results: In both groups the PSFS proved itself to be more sensitive in comparison to the ODI. The internal responsiveness of ODI improved ES= -0.75), (non-improved ES= -0.38). PSFS (improved ES= 1.96), (non-improved ES 0.77). The external responsiveness of ODI (AUC= 0.59), of PSFS (AUC= 0.83) (P= 0.0068). Constructs of both measurement instruments have a weak and a moderate correlation on measuring point 1 (r= -0.28) and 2 (r= -0.58). Conclusion: The German version of PSFS proves itself to be a feasible model and a method of high sensitivity in evaluating changes in the functional ability of patients with lumbar back pain. The instrument can be recommended to be used in clinical practice.