The Value of Total Knee Replacement in Patients With Knee Osteoarthritis and a Body Mass Index of 40 kg/m

BACKGROUND: Total knee replacement (TKR) is an effective and cost-effective strategy for treating end-stage knee osteoarthritis. Greater risk of complications among TKR recipients with BMI≥40kg/m(2) has raised concerns regarding the value of TKR in this population. OBJECTIVE: To assess the value of TKR in recipients with BMI≥40kg/m(2) using a cost-effectiveness analysis. DESIGN: Osteoarthritis Policy Model (OAPol) to assess long-term clinical benefits, costs, and cost-effectiveness of TKR in patients with BMI≥40kg/m(2). DATA SOURCES: Longitudinal studies and published literature to obtain TKR parameters, costs from Medicare Physician Fee Schedules, the Health Care Utilization Project, and published data. TARGET POPULATION: TKR recipients with BMI≥40kg/m(2) in the US TIME HORIZON: Lifetime PERSPECTIVE: Healthcare Sector INTERVENTION: TKR OUTCOME MEASURES: Cost, quality-adjusted life-years (QALYs), incremental cost-effectiveness ratios (ICERs), discounted at 3%/year RESULTS OF BASE-CASE ANALYSIS: TKR increased QALYs by 0.71 and lifetime medical costs by $25,200 among patients with BMI≥40kg/m(2) aged 50–65, resulting in an ICER of $35,200. TKR in patients aged >65 with BMI≥40kg/m(2) increased QALYs by 0.39 and costs by $21,100, resulting in an ICER of $54,100. RESULTS OF SENSITIVITY ANALYSIS: In TKR recipients with BMI≥40kg/m(2) and diabetes and cardiovascular disease, ICERs were below $75,000/QALY. Results were most sensitive to complication rates and preoperative pain levels. In the probabilistic sensitivity analysis at a $55,000/QALY willingness-to-pay threshold, TKR had a 100% and 90% likelihood of being a cost-effective strategy for patients aged 50–65 and >65, respectively. LIMITATIONS: Data are derived from multiple sources. CONCLUSION: From a cost-effectiveness perspective, TKR offers good value in patients with BMI≥40kg/m(2), including those with multiple comorbid conditions.