CC4 COST-EFFECTIVENESS ANALYSIS OF THE STEPPED EXERCISE PROGRAM FOR PATIENTS WITH KNEE OSTEOARTHRITIS (STEP-KOA) TRIAL

To evaluate the cost-effectiveness of the STepped Exercise Program for patients with Knee OsteoArthritis (STEP-KOA). The randomized control trial included 230 intervention and 115 control patients at two Veterans Affairs (VA) medical centers. A decision tree was used to simulate 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 needs. Of the 60% (n=138) progressing to Step 2, 59% (n=81) progressed to Step 3. A VA-owned tablet with data was provided to 15% (n=35) of STEP-KOA participants. Micro-costing was used to derive costs from the VA perspective using invoices and VA labor rates. Quality-of-life (QOL) was measured using EQ-5D-5L US utility weights and differential change between arms estimated using site- and sex-adjusted linear mixed models. Incremental cost-effectiveness ratios (ICER) were calculated as the difference in costs divided by the difference in quality adjusted life years (QALY) between arms at 9 months. A Monte Carlo probabilistic sensitivity analysis (PSA) with 1000 simulations was used to generate a cost-effectiveness acceptability curve. The trial found differential improvement in utility weights of 0.04 (95% confidence interval (CI) 0.003, 0.080; p=0.03) for STEP-KOA versus control at 9 months. In the base case, STEP-KOA resulted in an incremental gain of 0.03 QALYs and an incremental cost of $287 per patient for an ICER of $9,138. One-way sensitivity analyses found the largest sources of variation in the ICER were the impact on QOL and the proportion needing a VA-owned tablet. The PSA found a 99% probability of cost-effectiveness at $50,000 willingness-to-pay per QALY. STEP-KOA improves QOL by reducing KOA pain and has a high probability of cost-effectiveness. Resources needed to implement the program will decline as ownership of mobile health devices increases.