Sustainable care: what are the characteristics of people with asthma who successfully switch to low carbon inhaler devices?

Inhalers are responsible for much of the carbon footprint of respiratory therapies. Metered Dose Inhalers (MDIs) lead to greater carbon emissions than Dry Powder Inhalers (DPIs), and switching from MDIs to DPIs where feasible is a stated priority of the UK NHS. However, little is known about what patient factors are associated with a successful inhaler switch. Asthma + Lung UK asked UK asthma patients to complete a wide-ranging online survey in spring 2023. Participants were asked if they had been offered the chance to switch to a DPI, and if so if it had been successful. We compared demographic, economic and clinical factors between people with asthma who had a successful versus those with an unsuccessful switch (that is changed back to an MDI). 9,960 people replied (77.9% female; age 59.9±13.0) of whom 3321 (33.3%) accepted a switch. The change to DPI was successful in 2126 (64% of switchers). Demographic and economic factors were not associated with a successful switch. Compared to those who successfully changed device, unsuccessful switchers were more likely to report uncontrolled asthma (66.2% vs 57.5%*), use of unplanned care (31.8% vs 25.3%*) and requirement for >2 courses of oral corticosteroids (32.5% vs 24.9%*) in the past year (*all p<0.001). Awareness of the carbon impact of MDIs was not different between the two groups (70% vs 71.6%). In a large UK survey of people with asthma, a switch from MDI to equivalent DPI therapy was successful in a significant majority of those who attempted it. Unsuccessful switches were associated with subjective and objective markers of poor disease control rather than socio-demographic factors or environmental concerns.