Cost-Effectiveness of Weight-Loss Interventions Prior to Total Knee Replacement for Patients With Class III Obesity

Class III obesity (body mass index >40 kg/m² ) is associated with higher complications following total knee replacement (TKR), and weight loss is recommended. We aimed to establish the cost-effectiveness of Roux-en-Y gastric bypass (RYGB), laparoscopic sleeve gastrectomy (LSG), and lifestyle nonsurgical weight loss (LNSWL) interventions in knee osteoarthritis patients with class III obesity considering TKR.

Using the Osteoarthritis Policy model and data from published literature to derive model inputs for RYGB, LSG, LNSWL, and TKR, we assessed the long-term clinical benefits, costs, and cost-effectiveness of weight-loss interventions for patients with class III obesity considering TKR. We assessed the following strategies with a health care sector perspective: 1) no weight loss/no TKR, 2) immediate TKR, 3) LNSWL, 4) LSG, and 5) RYGB. Each weight-loss strategy was followed by annual TKR reevaluation. Primary outcomes were cost, quality-adjusted life expectancy (QALE), and incremental cost-effectiveness ratios (ICERs), discounted at 3% per year. We conducted deterministic and probabilistic sensitivity analyses to examine the robustness of conclusions to input uncertainty.

LSG increased QALE by 1.64 quality-adjusted life-years (QALYs) and lifetime medical costs by $17,347 compared to no intervention, leading to an ICER of $10,600/QALY. RYGB increased QALE by 0.22 and costs by $4,607 beyond LSG, resulting in an ICER of $20,500/QALY. Relative to immediate TKR, LSG and RYGB delayed and decreased TKR utilization. In the probabilistic sensitivity analysis, RYGB was cost-effective in 67% of iterations at a willingness-to-pay threshold of $50,000/QALY.

For patients with class III obesity considering TKR, RYGB provides good value while immediate TKR without weight loss is not economically efficient.