University of Exeter - Exeter Inflammatory Bowel Disease and Pharmacogenetics Research Group, St Mark’s Hospital, UK IBD Registry, Department of Gastroenterology, Royal Devon and Exeter Hospital NHS Foundation Trust, University Hospital Southampton NHS Foundation Trust, UK IBD Registry, UK IBD Registry, University College London Hospitals NHS Foundation Trust, UK IBD Registry, Western General Hospital, NHS Lothian, King's College Hospital - Department of Gastroenterology, Hull and East Yorkshire Hospitals, Government of the United Kingdom - Leeds Teaching Hospitals, Torbay and South Devon NHS Foundation Trust, St Mark’s Hospital, Independent and UK IBD Registry