[1] Kings Coll London, Sch Populat Hlth & Environm Sci, Dept Publ Hlth & Primary Care, 3rd Floor,Addison House,Guys Campus, London SE1 1UL, England
[2] Norwegian Inst Publ Hlth, Oslo, Norway
[3] South African Med Res Council, Hlth Syst Res Unit, Cape Town, South Africa
[4] Guys & St Thomas NHS Fdn Trust, Physiotherapy Dept, London, England
[5] Kings Coll Hosp NHS Fdn Trust, Pulm Rehabil & Integrated Resp Team, London, England
[6] Queen Mary Univ London, Barts & London Sch Med & Dent, Blizard Inst, Ctr Primary Care & Publ Hlth, London, England
[7] Imperial Coll London, Natl Heart & Lung Inst, London, England
[8] Guys & St Thomas NHS Fdn Trust, Lane Fox Resp Serv, London, England
[9] Univ Hosp Leicester NHS Trust, Ctr Exercise & Rehabil Sci, Leicester, Leics, England
[10] UCL, Dept Clin Educ & Hlth Psychol, London, England