[1] Churchill Hosp, Oxford Resp Trials Unit, Oxford OX3 7LJ, England
[2] Churchill Hosp, Oxford Pleural Dis Unit, Oxford OX3 7LJ, England
[3] Univ Oxford, Natl Inst Hlth Res, Oxford Biomed Res Ctr, Oxford OX3 7LE, England
[4] Musgrove Pk Hosp, Somerset Lung Ctr, Taunton, Somerset, England
[5] UCL, Med Res Council, Clin Trials Unit, London, England
[6] Blackpool Teaching Hosp NHS Fdn Trust, Blackpool, England
[7] Kings Mill Hosp, Mansfield, England
[8] Medway Maritime Hosp, Gillingham, England
[9] Basildon Univ Hosp, Basildon, England
[10] Univ Hosp South Manchester NHS Fdn Trust, Manchester, Lancs, England
[11] Royal Wolverhampton Hosp NHS Trust, Wolverhampton, W Midlands, England
[12] Rotherham Gen Hosp, Rotherham, S Yorkshire, England
[13] Vancouver Coastal Hlth, Vancouver, BC, Canada
[14] Univ Calif Davis, Med Ctr, Sacramento, CA 95817 USA
[15] Queen Alexandra Hosp, Portsmouth, Hants, England
[16] Cardiff & Vale Univ, Hlth Board, Cardiff, S Glam, Wales
[17] Univ Western Australia, Sch Med, Crawley, Australia
[18] Univ Western Australia, Ctr Asthma Allergy & Resp Res, Crawley, Australia
[19] Ipswich Hosp, Dept Resp Med, Ipswich, Suffolk, England
[20] Univ Bristol, Southmead Hosp, Dept Clin Sci, Acad Resp Unit, Bristol, Avon, England
[21] UCL, Res Dept Infect & Populat Hlth, Inst Epidemiol & Healthcare, London, England