The Patient-Specific Functional Scale - A useful tool for physiotherapists working in primary care

Purpose: To examine content validity, reliability and responsiveness of the Patient-Specific Functional Scale (PSFS), for patients with musculoskeletal disorders receiving physiotherapy in primary care. Design: A methodological study with a cross-sectional design for the investigation of content validity and reliability and a prospective cohort design for the investigation of responsiveness. Materials: For the study of content validity and reliability 81 patients were included. For the study of responsiveness 180 patients were included. Methods: Content validity was examined by categorizing the reported activities according to ICF. In the study of reliability Intraclass Correlation Coefficient (ICC), Smallest Error of Measurement (SEM) and Smallest Detectable Change (SDC) were calculated. Responsiveness was examined through a criterion approach. Area under the curve (AUC), sensitivity, specificity and Minimal Important Change (MIC) were calculated with Receiver Operating Characteristics (ROC). Results :Patients mainly reports problems at ICF-activity level. Reliability was acceptable for first reported activity (ICC>0.7), but poorer for activity 2 and 3 (ICC