Abstract / Summary
Pressurized metered-dose inhalers (pMDIs) are an important source of healthcare-related greenhouse-gas emissions, but decarbonization strategies may also alter medication costs, access, and clinical outcomes. Prior U.S. analyses have characterized these domains separately; the consequences of specific product- and regimen-level inhaler transitions remain incompletely integrated. We evaluated the clinical, economic, environmental, and distributional trade-offs of selected U.S. inhaler transitions. We conducted a U.S. scenario analysis among adults using nationally weighted 2023 Medical Expenditure Panel Survey dispensing data, 2025 National Average Drug Acquisition Cost data, and published product- or molecule-specific life-cycle greenhouse-gas estimates. Six product- or regimen-specific transitions were modeled. Observed acute-care utilization differences from a Veterans Health Administration cohort were applied only to the budesonide-formoterol pMDI-to-fluticasone-salmeterol dry powder inhaler transition. Deterministic, probabilistic, pricing, uptake, carbon-footprint, lower-global-warming-potential propellant, and distributional scenarios were evaluated. Clinical, economic, and environmental effects varied markedly by transition. Annual albuterol pMDI-to-DPI transition avoided an estimated 1,148,636 metric tons CO₂e but increased medication acquisition costs by 295.8 million and 315.7 million but slightly increased modeled emissions. In the VHA-aligned transition, 2.019 million modeled users generated 6,461 additional respiratory emergency-department users and 8,278 additional hospitalizations over 180 days; incremental acute-care costs were 770.0 million, and net healthcare savings were 41 in additional acquisition cost per switched albuterol inhaler to approximately $241 in savings per fluticasone-salmeterol fill; under national uninsured-rate reference scenarios, 8.3%–11.6% of modeled VHA-aligned clinical and economic effects were proportionally allocated to uninsured patients. Lower-global-warming-potential pMDI scenarios substantially attenuated the environmental advantage of device substitution. The consequences of inhaler decarbonization were product- and regimen-specific rather than determined by device class alone. Targeted transitions that account for clinical suitability, patient preference, affordability, and evolving lower-carbon pMDI options may better balance environmental and patient-centered outcomes compared to universal device substitution.