1 Department of Gastroenterology, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK; Department of Medicine, School of Clinical Medicine, University of Cambridge, Cambridge CB2 0QQ, UK. Electronic address: nn281@cam.ac.uk.
2 Gastroenterology and Hepatology, Hull and East Yorkshire Hospitals NHS Trust, Hull, UK; Hull York Medical School, University of Hull, Hull, UK.
3 Department of Gastroenterology, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK; Department of Medicine, School of Clinical Medicine, University of Cambridge, Cambridge CB2 0QQ, UK.
4 Department of Gastroenterology, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK.