Background: Inhaler mishandling is a common issue among patients suffering from asthma and is associated with poor clinical outcomes and greater consumption of health-care resources. Ease of use can improve inhaler technique and, possibly, patients' preference for their inhaler device, which in turn may lead to better adherence to therapy. Methods: This study investigated usability characteristics of NEXThaler Ò versus two other dry powder inhalers (DPIs; Diskus Ò and Turbuhaler