1. University of Liverpool; Department of Biostatistics; Block F, Waterhouse Building 1-5 Brownlow Hill Liverpool UK L69 3GL
2. National Institute for Health and Care Excellence; Centre for Clinical Practice; Level 1A, City Tower, Piccadilly Plaza Manchester UK M1 4BD
3. University of Manchester and University Hospital of South Manchester; Centre for Respiratory Medicine and Allergy, Institute of Inflammation and Repair; Manchester Academic Health Sciences Centre 46 Grafton Street Manchester UK M13 9NT
4. University of Sydney; Discipline of Physiotherapy, Faculty of Health Sciences; Rm No O156, O Block Sydney NSW Australia 2141
5. University of Sydney; Central Clinical School, Sydney Medical School; Sydney Australia NSW 2006