Evaluation of dry powder inhalers with a focus on ease of use and user preference in inhaler-naïve individuals.

Inhaler errors are common amongst inhaler users. Therefore, in the development work of new inhalation devices, it is important to characterize the ease of use of the inhalers. In this study four dry powder inhalers, Diskus, Easyhaler, Ellipta and Turbuhaler, were evaluated, focusing on ease of use and patient preference. The study used a triangular methodology. The sample consisted of 31 inhaler naïve individuals. Educational videos for all inhalers were watched, and afterwards, the use of all four inhalers was demonstrated in a random order. The demonstrations were videotaped. Thereafter they were checked against a predefined checklist and all mistakes were recorded. Only 33% of inhaler demonstrations were completed without the participants making any mistakes. The proportions of subjects who used the devices correctly were as follows: Diskus 48%, Easyhaler 19%, Ellipta 55% and Turbuhaler 16%. When comparing correct and incorrect inhaler technique for each inhaler pair the following differences were statistically significant: Diskus vs. Easyhaler (p<0.05), Ellipta vs. Easyhaler (p<0.01), Diskus vs. Turbuhaler (p<0.01), Ellipta vs. Turbuhaler (p<0.01). In the participants' ranking, the inhalers Ellipta, followed by Turbuhaler, were most often ranked as most preferred. Participants' preference of Ellipta over Easyhaler (p<0.01) and over Diskus (p<0.001) were statistically significant.