1 Centre for Trauma and Surgery, and GI Physiology Unit, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK.
2 Statistics Division, The George Institute for Global Health, UNSW, Sydney, Australia.
3 Department of Gastroenterology and Hepatology, University Hospital Zurich, Zurich, Switzerland.
4 Centre for Medical Imaging, University College London, London, UK.