The Value of Total Knee Replacement in Patients With Knee Osteoarthritis and a Body Mass Index of 40 kg/m or Greater : A Cost-Effectiveness Analysis.

Background: Total knee replacement (TKR) is an effective and cost-effective strategy for treating end-stage knee osteoarthritis. Greater risk for complications among TKR recipients with a body mass index (BMI) of 40 kg/m or greater has raised concerns about the value of TKR in this population.

Objective: To assess the value of TKR in recipients with a BMI of 40 kg/m or greater using a cost-effectiveness analysis.

Design: Osteoarthritis Policy Model to assess long-term clinical benefits, costs, and cost-effectiveness of TKR in patients with a BMI of 40 kg/m or greater.

Data Sources: Total knee replacement parameters from longitudinal studies and published literature, and costs from Medicare Physician Fee Schedules, the Healthcare Cost and Utilization Project, and published data.

Target Population: Recipients of TKR with a BMI of 40 kg/m or greater in the United States.

Time Horizon: Lifetime.

Perspective: Health care sector.

Intervention: Total knee replacement.

Outcome Measures: Cost, quality-adjusted life-years (QALYs), and incremental cost-effectiveness ratios (ICERs), discounted at 3% annually.

Results Of Base-case Analysis: Total knee replacement increased QALYs by 0.71 year and lifetime medical costs by $25 200 among patients aged 50 to 65 years with a BMI of 40 kg/m or greater, resulting in an ICER of $35 200. Total knee replacement in patients older than 65 years with a BMI of 40 kg/m or greater increased QALYs by 0.39 year and costs by $21 100, resulting in an ICER of $54 100.

Results Of Sensitivity Analysis: In TKR recipients with a BMI of 40 kg/m or greater and diabetes and cardiovascular disease, ICERs were below $75 000 per QALY. Results were most sensitive to complication rates and preoperative pain levels. In the probabilistic sensitivity analysis, at a $55 000-per-QALY willingness-to-pay threshold, TKR had a 100% and 90% likelihood of being a cost-effective strategy for patients aged 50 to 65 years and patients older than 65 years, respectively.

Limitation: Data are derived from several sources.

Conclusion: From a cost-effectiveness perspective, TKR offers good value in patients with a BMI of 40 kg/m or greater, including those with multiple comorbidities.

Primary Funding Source: National Institute of Arthritis and Musculoskeletal and Skin Diseases of the National Institutes of Health.