1 Division of Surgery and Interventional Science, University College London, London, UK.
2 Division of Surgery and Interventional Science, University College London, London, UK. [email protected].
3 Division of Surgery and Interventional Science, 4th Floor, University College London, UCL Medical School Building, 21 University Street, London, WC1E 6AU, UK. [email protected].
4 Queen Elizabeth Hospital, King's Lynn NHS Trust, Suffolk, UK.
5 Department of Medical Statistics, London School of Hygiene and Tropical Medicine, London, UK.
6 Department of Anaesthesia and Intensive Care, Papworth Hospital, Cambridge, UK.
7 Department of Innovative Clinical Trials, University Medical Centre Göttingen (UMG), Göttingen, Germany.