FAST and PSFS: Assessment and Validation of Two Functional Scales in Patients With Knee OA in Singapore

The new National One-Rehab framework mandates the use of the Patient-Specific Functional Scale (PSFS) as an outcome measure to track patients' rehabilitation progress. Anecdotally, we have encountered patients (especially elderly ≥ 65 years old) with difficulty understanding and completing such questionnaire accurately. We developed a pictorial functional scale (Functional Activity Scoring Tool, FAST) with reference to the successful application of the Wong-Baker FACES pain rating scale. Concurrently, we hope to validate PSFS and FAST against Knee injury and Osteoarthritis Outcome Score (KOOS) which is validated in Singapore population. This study aims to investigate the reliability and validity of the PSFS and FAST in patients with knee osteoarthritis. We hypothesize that both the PSFS and FAST can be used to measure difficulty in performing activities of daily living in patients with knee osteoarthritis in a reliable and valid manner. The FAST and PSFS questionnaires will be administered to patients in SingHealth Polyclinics with knee osteoarthritis to explore the psychometric and clinimetric properties. Eligibility criteria were: age 45 and above, proficient in English, diagnosed with knee osteoarthritis. Patients were excluded if they have underlying medical or trauma conditions (i.e., trauma, fracture, infection, inflammatory disease, tumor), history of knee surgery within the last 3 months, or clinically recognizable cognitive impairment. Eligible patients will be informed about the purpose of the study and the confidentiality and anonymity of the process. After giving written consent they will complete a questionnaire on demographic and clinical characteristics and the sets of outcome measures (FAST, KOOS, PSFS). Participants will then return at two-to-three weeks later to complete the sets of outcome measures again and GROC, and to state their preferred outcome measures. Statistical analysis will be conducted to evaluate the validity and reliability of PS