[1] Royal Edinburgh Infirm, Dept Resp Med, Edinburgh EH16 4SA, Midlothian, Scotland
[2] Univ Edinburgh, Edinburgh EH8 9YL, Midlothian, Scotland
[3] Norfolk & Norwich Univ Hosp, Dept Resp Med, Norwich, Norfolk, England
[4] Fulcrum Med Practice, Middlesbrough, Cleveland, England
[5] British Thorac Soc, London, England
[6] Royal Brompton Hosp, Dept Resp Med, London SW3 6LY, England