Purpose: This study presents an updated health economic model for evaluating the long-term cost-effectiveness of interventions in overweight and obesity, integrating new clinical evidence from the SURMOUNT clinical trial programme and methodological advancements in type-2 diabetes and obstructive sleep apnea (OSA) modelling.
Patients and methods: An updated individual patient simulation model evaluated the costs and long-term clinical outcomes of tirzepatide (5, 10, 15.0 mg) versus diet and exercise (D&E) alone in patients with a body mass index (BMI) ≥30 kg/m2 (obesity), or BMI ≥27 to <30 kg/m2 (overweight) + ≥1 obesity-related complication with a UK healthcare perspective. Key improvements over a previously published model were introduced, including modelling remission and progression of OSA, capturing realistic patterns of D&E discontinuation, incorporating HbA1c as a continuous cardiometabolic endpoint and transition to R-based implementation over VBA. Primary results include incremental cost-effectiveness ratios (ICERs; cost/QALY), costs, life years gained and quality-adjusted life years (QALYs). Secondary outcomes including clinical outcomes, random seed and cohort convergence, deterministic sensitivity results and run time were also calculated.
Results: The refined model predicted that all tirzepatide doses were cost-effective compared to D&E at a £20,000/QALY gained WTP (willingness-to-pay) threshold (ICERs: £8,327-£10,157). Refined estimation of long-term D&E discontinuation and OSA remission likely contributed to lower incremental costs, higher QALYs, and reduced ICERs compared with the previous model, aligning outcomes more closely with expected benefits from weight management treatment. Transitioning to R-based implementation reduced run time (e.g. by 4.52 h for deterministic sensitivity analyses) and enhanced model stability in all analyses conducted.
Conclusion: This enhanced economic model represents a significant advancement in the evaluation of obesity pharmacotherapy, designed to enhance clinical relevance, technical robustness, and increase usability. It supports evidence-based decision-making for chronic weight management treatment in the UK, and beyond, while offering a scalable platform for future therapeutic evaluations.
Keywords: I10; I15; R-based implementation; diet; obesity; patient simulation modelling; tirzepatide; weight management.
In this study, researchers improved a computer model that estimates how weight-loss treatments affect people’s health and healthcare costs over their lifetime. The model focuses on adults in the UK who are overweight or have obesity and at least one related health condition. It compares treatment with tirzepatide plus diet and exercise to diet and exercise alone. It builds on an earlier model but includes several important updates based on new clinical evidence and feedback from experts.The updated model more accurately reflects real-world health changes by tracking how weight loss affects conditions such as obstructive sleep apnea (a condition where breathing repeatedly stops and starts during sleep) and type 2 diabetes over time. The model can show that people’s sleep apnea may improve or no longer be present as they lose weight with treatment. It also reflects that lifestyle changes such as diet and exercise are often stopped over time, and that their health benefits tend to fade once support ends. In addition, the model now tracks blood sugar levels continuously, rather than using broad categories, allowing a more realistic estimate of how treatments affect the risk of developing type 2 diabetes and its complications.The model was rebuilt using modern statistical software, which made it faster, and more reliable to test under different assumptions, while still keeping a familiar Excel interface. Example results showed that tirzepatide improved health outcomes and was cost-effective compared with diet and exercise, largely by reducing the risk of type 2 diabetes, knee replacement surgery, and long-term sleep apnea.Overall, this study presents a more realistic way to estimate the long-term health and economic impact of obesity treatments in the UK. The improved model can help decision-makers understand the full benefits of modern weight-loss medicines and support evidence-based choices for NHS funding and policy.