1 Trial Manager, Oxford Respiratory Trials Unit, Nuffield Department of Medicine, University of Oxford, Oxford OX2 7LE.
2 Consultant Respiratory Physician, Department of Respiratory Medicine, Sherwood Forest Hospitals NHS Foundation Trust, Mansfield.
3 Consultant Respiratory Physician, Department of Respiratory Medicine, Norfolk and Norwich University Hospitals, Norwich.
4 Professor of Respiratory Medicine, Oxford Respiratory Trials Unit, Nuffield Department of Medicine, University of Oxford, Oxford, and Oxford NIHR Biomedical Research Centre, Oxford.