Nan Zhou1, Anita McGrogan2 & Matthew D Jones2
1School of Chemistry, University of Bristol, Bristol, BS8 1TS, UK
2Department of Life Sciences, University of Bath, Bath, BA2 7AY, UK
Summary
National policy initiatives in the UK, such as the NHS Net Zero strategy, have encouraged switching from pressurized metered dose inhalers (pMDIs) to more environmentally sustainable dry powder inhalers (DPIs). However, real-world evidence on the impact of such nonclinical switching remains limited. This retrospective cohort study used Clinical Practice Research Datalink (CPRD) data to evaluate the characteristics and outcomes, specifically discontinuation, persistence, and switch-back, of 13,482 asthma patients who switched between pMDIs and DPIs without changing drug class or dose from 2015 to 2024 in English primary care. A higher number of patients switched from pMDI to DPI compared with those who switched from DPI to pMDI, reflecting national policy direction. However, persistence was lower in this group, particularly among older adults and women. In contrast, patients switching to pMDIs showed consistently higher persistence. Approximately 25-30% of all switchers reverted to their original inhaler. Monthly switching trends revealed strong alignment with NHS policy events, even prior to their formal implementation, indicating that policy signals can influence clinical behavior. These findings highlight the importance of patient-centred approaches to inhaler switching, especially for groups at higher risk of discontinuation. Further research is needed to assess safety and effectiveness outcomes of switching, including exacerbation control and treatment success.