1. Bariatric Unit, Department of General Surgery, Sunderland Royal Hospital, South Tyneside and Sunderland NHS Trust, Kayll Rd, Sunderland SR4 7TP, UK
2. Bariatric & Upper GI Surgery Unit, Birmingham Heartlands Hospital, University Hospital Birmingham NHS Foundation Trust, Bordesley Green E, Birmingham B9 5SS, UK
3. Upper Surgery Unit, NHS Forth Valley, Stirling Rd, Larbert FK5 4WR, UK
4. Upper GI Surgery Unit, Whittington Health NHS Trust, Magdala Ave, Highgate, London N19 5NF, UK
5. Upper GI Surgery Unit, St. George's University Hospitals NHS Foundation Trust, Blackshaw Rd, Tooting, London SW17 0QT, UK
6. Faculty of Health Sciences and Wellbeing, University of Sunderland, Sunderland SR1 3SD, UK