[1] Worcestershire Acute Hosp NHS Trust, Worcestershire Royal Hosp, Worcester, England
[2] Univ Manchester, Manchester, Lancs, England
[3] Univ Manchester, Univ Hosp South Manchester NHS Fdn Trust, Manchester Acad Hlth Sci Ctr, Manchester, Lancs, England
[4] Univ S Manchester Hosp, Manchester M20 8LR, Lancs, England
[5] Royal Blackburn Hosp, Blackburn, Lancs, England
[6] St Thomas Hosp, Lane Fox Unit, London, England
[7] Lancashire Teaching Hosp NHS Trust, Preston, Lancs, England
[8] Univ Coll London Hosp, London, England
[9] Univ Coll London Hosp, Biomed Res Ctr, MRC,Clin Trials Unit, Natl Inst Hlth Res, London, England
[10] Univ Oxford, NIHR Oxford Biomed Res Ctr, Oxford Ctr Resp Med, Oxford Resp Trials Unit, Oxford, England