[1] Imperial Coll Healthcare NHS Trust, Renal Transplant Directorate, London, England
[2] Univ Sunderland, Fac Hlth Sci & Wellbeing, Sci Complex, Sunderland, England
[3] Sunderland Royal Hosp, Bariatr Surg Unit, Directorate Gen Surg, Sunderland, England
[4] Univ Coll London Hosp NHS Fdn Trust, Dept Gen Surg, London, England
[5] Royal Infirm Edinburgh NHS Trust, Hepatobiliary Pancreat Surg Serv, Directorate Gen Surg, Edinburgh, Midlothian, Scotland
[6] Univ Edinburgh, Dept Clin Surg, Edinburgh, Midlothian, Scotland
[7] Imperial Coll London, Dept Surg & Canc, London, England