Enhancing economic modelling in obesity: integrating novel type 2 diabetes progression & obstructive sleep apnea remission - a UK case study.

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/m(obesity), or BMI ≥27 to <30 kg/m(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.