Are Semaglutide and Tirzepatide Worth the Cost for People With Knee Arthritis and Obesity?

The researchers used the Osteoarthritis Policy Model, a validated microsimulation model of knee osteoarthritis, to estimate lifetime health benefits and costs. They compared five weight loss strategies: semaglutide, tirzepatide, laparoscopic sleeve gastrectomy, Roux-en-Y gastric bypass, and diet and exercise. Input data came from published clinical trials and the U.S. Office of Health Policy. The base-case cohort had a mean BMI of 40 kg/m² and a pain score of 71 out of 100. Outcomes were measured in quality-adjusted life-years and costs from healthcare and societal perspectives.

Millions of people live with both knee osteoarthritis and obesity, conditions that worsen each other. GLP-1 receptor agonists like semaglutide and tirzepatide have shown they can reduce both weight and knee pain, but these drugs are expensive. This study provides decision-makers with concrete data showing that both drugs represent a reasonable investment in health outcomes, with tirzepatide offering the better value — important information as payers and health systems decide whether to cover these medications for osteoarthritis patients.

GLP-1 receptor agonists have become blockbuster drugs for weight loss and diabetes, but their high costs have sparked debate about who should get access to them. This study extends that conversation into osteoarthritis — a condition where obesity directly worsens joint damage and pain. As insurance coverage decisions for these drugs evolve, health economic analyses like this one provide evidence that payers can use to justify or restrict coverage for specific patient populations. The finding that bariatric surgery still outperforms drugs on cost-effectiveness also highlights the ongoing tension between surgical and pharmacological approaches to obesity.

This is a modeling study based on published data rather than a head-to-head clinical trial. The results are sensitive to assumptions about medication costs, treatment efficacy, and baseline BMI. Real-world adherence, side effects, and long-term outcomes may differ from model inputs. Data were drawn from multiple sources, which may introduce heterogeneity.