Responsiveness and the Minimal Important Change of Knee Injury and Osteoarthritis Outcome Score Following Physiotherapy Intervention in Iraqi People with Knee Osteoarthritis

Background: The Knee Injury Osteoarthritis Outcome Score (KOOS) is a widely used patient-reported questionnaire to evaluate individuals with knee osteoarthritis or a history of knee injuries. Objectives: The aim of this study was to evaluate the responsiveness and establish the minimal important change (MIC) for the Arabic version of KOOS in Iraqi individuals with knee osteoarthritis following physiotherapy intervention. Methods: Fifty volunteers (13 male and 37 female, mean age: 59.3±9.6 years old) with an orthopedic diagnosis of knee osteoarthritis participated in this study. The Arabic KOOS was completed by the participants once before the intervention and once after completing a 4-week physiotherapy treatment program. A seven-item global rating of change scale was used as an external anchor to assess the participants' opinion about the treatment and its possible changes. Responsiveness was evaluated by calculating the receiver operating characteristic (ROC) curve, and the MIC was established by identifying an optimal cut-off on the ROC curve. Results: All subscales of the Arabic KOOS showed an area under the curve > 0.70. The MICs reflecting the values required by the participants to feel the improvement were 15.5, 14.5, 11, 11.5, and 12.5 for the pain, symptoms, activities of daily living, sports and recreation, and quality of life subscales, respectively. Conclusions: All subscales of the Arabic KOOS are responsive to physiotherapy treatment. Therapists and researchers can use the MIC values to evaluate whether their prescribed treatment was satisfactory and effective from their patients' point of view.