Table 1.

Attributes and levels used in the discrete choice experiment

Attribute	Definition given to the participants in the survey	Levels
Multidose or unidose system (ease of use)	A'multidose'inhaler contains multiple doses within the inhaler. A'unidose'inhaler uses individual capsules and needs to be refilled before each inhalation. Therefore, a'unidose'inhaler always requires more steps before inhalation compared to a multidose system	• Unidose system • Multidose system
Reduction in number of exacerbations (flare-ups) per year (efficacy)	The use of inhaler can reduce the likelihood of exacerbations in the next year. This reduction varies depending on the type of inhaler and serves as an indicator of the effectiveness of the inhaler	• Likely to reduce one exacerbation in the upcoming year • Likely to reduce two exacerbations in the upcoming year • Likely to reduce three exacerbations in the upcoming year
Likelihood of side effects (safety)	The use of inhaler can cause side effects, such as dry mouth or palpitations. These side effects may lead to non-adherence to the agreed regimen	• Likely to experience no side effects • Likely to experience mild side effects, but they do not interfere with taking the medicine • Likely to experience moderate to severe side effects that may stop you from taking the medicine
Out of pocket costs	Annual costs the patient has to pay for using inhalers, not reimbursed by the health insurer	• €50,- per year • €150,- per year • €250,- per year
Global warming potential (GWP)	pMDIs contain greenhouse gases. The environmental impact of one inhalation from a pMDI, is 25 times higher than that of a low GWP inhaler (i.e. DPI or soft-mist inhaler). With average use of a pMDI (5.5 packages per year), the CO₂ equivalent emissions per year are equivalent to a round-trip flight from Amsterdam to Paris	• High GWP inhaler • Low GWP inhaler