OBJECTIVES: This study estimated the cost-effectiveness of tirzepatide (5mg, 10mg, 15mg) compared to liraglutide (3mg) both adjunct to a reduced-calorie diet and increased physical activity in patients with a body mass index (BMI) ≥30kg/m² (obesity), or with a BMI≥27 to <30kg/m² (overweight) + ≥1 weight-related complication using UK inputs.

METHODS: A lifetime simulation model evaluated the costs and long-term clinical outcomes of each treatment. The base-case population was the population from the SURMOUNT-1 trial, and a subgroup analysis was conducted in liraglutide’s UK reimbursed population (BMI≥35kg/m² + prediabetes + high risk of cardiovascular disease) with a two-year stopping rule for liraglutide to reflect reimbursement criteria. Treatment efficacy was informed by a network meta-analysis, using efficacy estimand in the trial population and treatment-regimen estimand in the subgroup analysis due to data availability. Patients were at risk of developing weight-related complications such as diabetes and cardiovascular complications, calculated using published risk equations and modelling changes in risk factors. Incremental cost-effectiveness ratios (ICERs; cost/quality-adjusted life year [QALY]) were calculated.

RESULTS: In the trial population, all doses of tirzepatide were dominant to liraglutide, with cost savings and QALY gains. Tirzepatide remained cost-effective in liraglutide’s UK reimbursed population (ICERs £7,500−£9,300/QALY); the change in results is largely due to the two-year stopping rule for liraglutide in this population. In both populations, all doses of tirzepatide demonstrated reductions in at least five of seven complications compared to liraglutide, most notably for knee replacements (29−46% reduction) and diabetes (25−48% reduction). This is likely driven by comparative efficacy on key risk factors including weight loss (8% versus 15–22%) and prediabetes reversal (88% versus 93–94%) for liraglutide versus tirzepatide, respectively.

CONCLUSIONS: Based on this simulation model, at the UK willingness-to-pay threshold (£20,000), tirzepatide is a cost-effective treatment compared to liraglutide for overweight and obesity, in the trial and liraglutide’s UK reimbursed population.