5G-04 - Trends in Prescription Fills and Out-of-Pocket Costs of Inhaler Devices by Global Warming Potential in the U.S.

Background: To address the environmental impact of inhalers with high GWP, the US ratified the Kigali Amendment to the Montreal Protocol in 2022 to reduce and restrict the use of hydroflourocarbons (HFCs), including from HFA MDIs, and implemented the American Innovation and Manufacturing Act to encourage the development of inhaler devices with low GWP. Despite these federal policies and a recent US Senate investigation highlighting concerns about the restricted availability and high cost of inhalers, particularly DPIs, due to limited competition,4 there is a lack of information on the affordability and use of inhaler devices based on their GWP in the U.S.

Objectives: In this study, we analyze trends in prescription fills and out-of-pocket costs for inhaler devices and quantify their potential impact on carbon dioxide equivalent (CO2e) emissions in the U.S.

Methods: We used IQVIAs National Prescription Audit PayerTrak, which captures detailed information on all prescriptions filled and dispensed to individuals at retail pharmacies in the U.S. We calculated monthly fills (primary outcome) and mean out-of-pocket costs (secondary outcome) for inhaler devices by product type (MDI, DPI and SMI) between January 2021 and July 2024. We analyzed these outcomes for each product type by drug class (e.g., short-acting  agonists [SABA]) and specific inhalers (e.g., Albuterol HFA). We also calculated total CO2e emissions by product type, drug class, and for specific inhalers

Results: Between January 2021 and July 2024, monthly prescription fills for inhaler devices increased modestly from 8,352,741 to 8,446,527 (p=0.03). HFA MDIs consistently accounted for over 71% of fills, while mean out-of-pocket costs (OOPC) were significantly higher for DPIs ($38.6) and SMIs ($35.5) compared to MDIs ($14.8) during this period. While the share of MDIs varied across drug classes, OOPC were consistently lower for MDIs. Among LABA/ICS inhalers, DPIs represented 50% of fills but had higher OOPC than MDIs ($29.9 vs. $25.3; p< 0.01). For SABAs, MDIs - which included 15 albuterol products - accounted for nearly all fills and had the lowest OOPC ($7.79) of any inhaler device. Most inhaler devices had only one brand, or generic product (many of which were authorized generics) available on the market. HFA MDIs contributed 98.9% of the 2.34 million metric tons (MMT) of CO₂e emissions from inhalers, with SABAs responsible for 73.4% of emissions and albuterol HFA alone accounting for 63.3%.

Conclusions: Efforts to increase the use of DPIs and SMIs and, in turn, reduce carbon emissions are needed in the U.S. Such efforts should ensure the availability and affordability of low GWP inhalers, particularly for HFA MDI inhalers widely used and disproportionately contributing to inhaler-related emissions (e.g., albuterol).