1 Royal Brompton Hospital, London, United Kingdom.
2 University of Queensland Thoracic Research Centre, Department of Thoracic Medicine, The Prince Charles Hospital, Chermside, Queensland, Australia.
3 University of Queensland Thoracic Research Centre, Department of Thoracic Medicine, The Prince Charles Hospital, Chermside, Queensland, Australia. Electronic address: kwun_fong@health.qld.gov.au.