Abstract
OBJECTIVE: To quantify, compare and analyse the carbon emissions of biologic treatments for severe asthma. DESIGN: Cradle-to-gate carbon emissions (from raw materials to finished product) for six monoclonal antibody therapies, benralizumab, dupilumab, mepolizumab, omalizumab, reslizumab and tezepelumab, were estimated using Medicine Carbon Footprint Classifier, a standardised, mass-based method for medicine carbon footprinting. A representative patient, eligible for all therapies, was defined to enable comparisons. Sensitivity, scenario and pairwise analyses were conducted to explore variations in emissions and opportunities for reduction. OUTCOME MEASURES: The primary outcome was first-year carbon emissions of biologic treatments for a representative patient with severe asthma, expressed in kg CO(2)e. Additional outcome measures were the effect of varying the electricity source on treatment emissions and emissions associated with alternative biologic choices. RESULTS: First-year treatment emissions for the representative patient ranged from 1.1 kg CO(₂)e with benralizumab to 188.9 kg CO(2)e with dupilumab, a 172-fold difference. Variation was driven by the active pharmaceutical ingredient per preparation (30-300 mg), number of preparations required for first-year treatment (8-52) and manufacturer's proportion of non-fossil fuel electricity (NFFE) (22%-91%). Sensitivity analysis showed that increasing NFFE to 100% could reduce emissions by 29%-90% and the difference between the highest and lowest emission treatments by 91%. Pairwise comparison showed that selecting any biologic instead of dupilumab could reduce emissions by 134-188 kg CO(2)e per patient-year, equivalent to 340-478 car miles. The emission differences between treatment with benralizumab, mepolizumab and tezepelumab were minimal. CONCLUSIONS: The carbon footprints of biologic treatments for severe asthma vary widely, driven primarily by differences in dose and manufacturer electricity sources. Our analyses highlight near-term opportunities to reduce emissions, including replacing fossil fuel electricity with renewable or nuclear sources (NFFE) and optimising dosing practices. The approach can be applied across other therapeutic areas to support carbon-informed prescribing and healthcare decarbonisation.