Carbon Emission Impact of Semaglutide in People with Obesity in the UK Using a Disease Modelling Approach

We aimed to assess the carbon footprint and clinical outcomes of once-weekly semaglutide in people with overweight or obesity in the UK using a disease modelling approach.

A per-patient carbon footprint analysis was conducted to estimate emissions related to obesity management with semaglutide 2.4 mg as an add on to diet and exercise versus diet and exercise alone. A Markov state-transition cohort model (Core Obesity Model) was used for the analysis. Data were sourced from STEP and SELECT trials across three populations: (1) body mass index [BMI] ≥ 30 or ≥ 27 with one or more obesity-related complications (BMI30+/BMI27+C), (2) BMI ≥ 27 with one or more complications, including type 2 diabetes mellitus (BMI27+C), and (3) BMI ≥ 27 with established cardiovascular disease (BMI27+CVD). Carbon emissions were estimated using resource-based and cost-based methods. Key outcomes included life-years, quality-adjusted life-years, and incremental carbon footprint effectiveness ratio.

In the BMI30+/BMI27+C and BMI27+C populations, semaglutide was dominant, yielding 0.30 and 0.25 additional life-years, 0.51 and 0.46 additional quality-adjusted life-years, while reducing lifetime carbon emissions by 1.8% (9850 vs 10,030 kg of CO₂ equivalent [CO₂e]) and 1.9% (9792 vs 9983 kg CO₂e), respectively. Manufacturing emissions of semaglutide were offset by reductions in carbon emissions resulting from fewer obesity-related complications. In the BMI27+CVD population, semaglutide improved life-years by 0.56 and quality-adjusted life-years by 0.59, but emissions increased (14,700 vs 14,444 kg CO₂e) because of longer survival and increased monitoring. Scenario and sensitivity analyses confirmed the robustness of the results.

Semaglutide offers both clinical and environmental benefits in obesity management, supporting the UK's net-zero emissions goals.