[1] Univ Nottingham, Nottingham City Hosp, Div Epidemiol & Publ Hlth, Clin Sci Bldg, Nottingham NG5 1PB, England
[2] Univ Nottingham, Nottingham City Hosp, Div Resp Med, Clin Sci Bldg, Nottingham NG5 1PB, England
[3] Aintree Univ Hosp NHS Fdn Trust, Longmoor Lane, Liverpool L9 7AL, Merseyside, England
[4] Nottingham Univ Hosp, Hayward House, Nottingham, England
[5] Univ Nottingham, Nottingham, England
[6] Queen Elizabeth Hosp Birmingham, Mindelsohn Way, Birmingham B15 2GW, W Midlands, England
[7] Univ Hosp Derby & Burton NHS Fdn Trust, Uttoxeter Rd, Derby DE22 3NE, England