Conflict of interest: F. Yang reports payment or honoraria for lectures, presentations, manuscript writing or educational events from GSK and AstraZeneca, support for attending meetings from AstraZeneca, and is a member of the British Thoracic Society Asthma Specialist Advisory Group. A. Bossios reports grants from AstraZeneca, payment or honoraria for lectures, presentations, manuscript writing or educational events from Chiesi, GSK and AstraZeneca, and leadership roles with European Respiratory Society as Head of Assembly 5 (Airway diseases, asthma, COPD, and chronic cough), co-chair of the Nordic severe asthma network, member of the steering committee of SHARP, the ERS severe asthma Clinical Research Collaboration, and is a member of the steering committee of the Swedish National Airway Register.