ACKNOWLEDGEMENTS:
The authors thank the patients who participated in this study and the WATCH study team who conducted it. They also acknowledge the support of the National Institute for Health Research (NIHR) Southampton Biomedical Research Centre and NIHR Clinical Research Facility, which are funded by NIHR and are a partnership between the University of Southampton and University Hospital Southampton NHS Foundation Trust. The authors also acknowledge a non-promotional grant from Novartis (£35,000) and initial assistance through a charitable grant (£3,500) for relevant patient costs (e.g. parking) from the Asthma, Allergy & Inflammation Research Charity. The WATCH study itself is not externally funded.