[1] Imperial Coll London, Med Informat & Decis Making, London, England
[2] Nottingham Univ Hosp NHS Trust, Queens Med Ctr, Acute & Obstetr Med, Nottingham, England
[3] Cent & North West London NHS Fdn Trust, London, England
[4] Swansea Bay Univ Hlth Board, Morriston Hosp, Anaesthet Dept, Swansea, W Glam, Wales
[5] Imperial Coll NHS Trust, St Marys Hosp, London, England
[6] Imperial Coll London, Dept Surg & Canc, London, England