Cost and Quality of Life Outcomes of the STepped Exercise Program for Patients With Knee OsteoArthritis Trial

Objectives: This study aimed to evaluate the cost-effectiveness of the randomized clinical trial STEP-KOA (STepped Exercise Program for patients with Knee OsteoArthritis). Methods: The trial included 230 intervention and 115 control participants from 2 Veterans Affairs (VA) medical centers. A decision tree simulated outcomes for cohorts of patients receiving arthritis education (control) or STEP-KOA (intervention), which consisted of an internet-based exercise training program (step 1), phone counseling (step 2), and physical therapy (step 3) according to patient's response. Intervention costs were assessed from the VA perspective. Quality of life (QOL) was measured using 5-level EQ-5D US utility weights. Incremental cost-effectiveness ratios (ICERs) were calculated as the difference in costs divided by the difference in quality-adjusted life-years (QALYs) between arms at 9 months. A Monte Carlo probabilistic sensitivity analysis was used to generate a cost-effectiveness acceptability curve. Results: The adjusted model found differential improvement in QOL utility weights of 0.042 (95% confidence interval 0.003-0.080; P=.03) for STEP-KOA versus control at 9 months. In the base case, STEP-KOA resulted in an incremental gain of 0.028 QALYs and an incremental cost of $279 per patient for an ICER of $10 076. One-way sensitivity analyses found the largest sources of variation in the ICER were the impact on QOL and the need for a VA-owned tablet. The probabilistic sensitivity analysis found a 98% probability of cost-effectiveness at $50 000 willingness-to-pay per QALY. Conclusions: STEP-KOA improves QOL and has a high probability of cost-effectiveness. Resources needed to implement the program will decline as ownership of mobile health devices increases.