[1] Inst Epidemiol & Appl Hlth Res, London, England
[2] UCLH Surg Outcomes Res Ctr, Dept Appl Hlth Res, London, England
[3] Univ Coll Hosp, Dept Anaesthesia & Perioperat Med, London, England
[4] Royal Coll Anaesthetists, Natl Inst Acad Anaesthesias, Hlth Serv Res Ctr, London, England
[5] Alfred Hosp, Dept Anaesthesia & Perioperat Med, Melbourne, Vic, Australia
[6] Monash Univ, Melbourne, Vic, Australia
[7] Monash Univ, Dept Epidemiol & Prevent Med, Hlth Serv Management & Res Unit, Alfred Ctr, Melbourne, Vic, Australia
[8] Geneva Univ Hosp, Div Anaesthesia, Dept Anaesthesiol Pharmacol & Intens Care, Geneva, Switzerland
[9] Univ Southampton, Univ Hosp Southampton NHS Fdn Trust, Crit Care Res Grp, Southampton NIHR Biomed Res Ctr, Southampton, Hants, England
[10] Royal Lancaster Infirm, Dept Anaesthesia, Lancaster, England