Determination of the minimal clinically important difference (MCID for patient-reported outcome measures evaluating the effectiveness of exercise treatment in knee osteoarthritis

The effectiveness of knee osteoarthritis (OA) treatments is primarily assessed through Patient-Reported Outcome Measures (PROMs). Understanding whether statistically significant improvements observed in patients after treatment translate into clinical significance, managing the treatment, and calculating sample sizes for research require determining the "Minimal Clinically Important Difference" (MCID) values for these scales. Hence, the aim of this thesis is to calculate the MCID values for widely used outcome scales, including the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Lower Extremity Functional Scale (LEFS), and Oxford Knee Score (OKS), as well as knee flexion Range of Motion (ROM) assessments in knee OA patients. Ninety-four patients diagnosed with stage 2 and 3 knee OA were included, undergoing a supervised 15-session exercise program. Sociodemographic data were recorded, and WOMAC, LEFS, OKS, and knee flexion ROM were evaluated three times: before treatment, after treatment (6 weeks), and at the 4-month follow-up. MCID values were calculated using the reference-based calculation method and a 5-point global change score. The global change score recorded the level of improvement after treatment for each patient. Patients were categorized into two groups: those showing improvement and those with unchanged conditions. The average difference between post-treatment (6 weeks and 4 months) and pre-treatment averages was calculated for each scale. Based on this difference, a ROC curve was drawn, and AUC and MCID were calculated. Upon examining the results, statistically significant improvements were found in all scales except knee flexion ROM at the end of treatment and the 4-month follow-up (p<0.05). The MCID values were found to be 10.5 for WOMAC, 9.5 for LEFS, and 7.5 for OKS, with moderate to high sensitivity and specificity after treatment. These values changed to 11.5, 13.5, and 6.5, respectively, at the 4-month follow-up. MCID could not be calculated for knee flexion ROM due to a lack of statistically significant improvement between groups. As the calculated MCID results from evidence-based conservative knee OA treatment programs in the literature are insufficient, the findings of this thesis fill a significant gap and contribute to academic research.