A cost-effectiveness analysis of behavioural, pharmacological, and surgical obesity treatments in Canada

Aims: Effective weight management pharmacotherapies are a new alternative to bariatric surgery or health behaviour intervention (HBI) alone. Comparative cost-effectiveness evaluations can guide decision-making. We aimed to evaluate the cost-effectiveness of sleeve gastrectomy (SG), Roux-en-Y gastric bypass (RYGB), semaglutide, tirzepatide, and HBI compared to no treatment in preventing cardiometabolic complications among Canadian adults with class III obesity. Materials and Methods: We developed a cohort-based Markov model with a 40-year time horizon. We examined cardiometabolic complications in 40-year-olds with class III obesity (BMI ≥40 kg/m²) without type 2 diabetes or cardiovascular disease at baseline. We compared SG, RYGB, semaglutide 2.4 mg, tirzepatide 15 mg, HBI, and no treatment. We obtained data on treatment effects, probabilities, utilities, and costs from published literature. We expressed effectiveness in quality-adjusted life years (QALYs) and estimated costs from a Canadian public payer perspective. Outcomes included incremental cost-effectiveness ratios (ICERs) evaluated at a CAD $50 000/QALY willingness-to-pay threshold. Results: RYGB and HBI were cost-effective strategies. HBI was cost-effective versus no treatment (ICER $14 279/QALY). RYGB demonstrated the highest QALYs (20.20) and was the most cost-effective strategy versus tirzepatide (ICER $44 667/QALY). Semaglutide and SG were strongly dominated due to higher costs and lower effectiveness. Tirzepatide was extendedly dominated by RYGB. Sensitivity analyses confirmed these findings and showed that lower drug prices could improve pharmacotherapy cost-effectiveness. Conclusions: RYGB and HBI are cost-effective for managing class III obesity. While RYGB provided the greatest health gains, access remains limited. Neither pharmacotherapy was cost-effective at current prices. Lower drug prices could significantly improve pharmacotherapy cost-effectiveness.