1 Department of Metabolic and Investigative Medicine, Commonwealth building, Hammersmith Hospital, Imperial College London, London, United Kingdom.
2 Department of Upper Gastrointestinal and Bariatric Surgery, St George's Hospital, London, United Kingdom; Population Health Research Institute, St George's, University of London, London, United Kingdom.
3 Department of Upper Gastrointestinal and Bariatric Surgery, St George's Hospital, London, United Kingdom.
4 Southmead Hospital, Bristol, United Kingdom.
5 Leeds Teaching Hospitals, Leeds, United Kingdom.
6 Royal Cornwall Hospital, Treliske, United Kingdom.
7 Gloucestershire Hospitals NHS Trust, Cheltenham, United Kingdom.
8 Hull and East Yorkshire Hospital, Hull, United Kingdom.
9 Dendrite Clinical Systems Ltd, Henley-on-Thames, United Kingdom.
10 Queen Alexandra Hospital, Portsmouth, United Kingdom.
11 Department of Upper Gastrointestinal and Bariatric Surgery, St George's Hospital, London, United Kingdom; Department of Upper GI and Bariatrics, Hebei Medical University, Hebei Sheng, China.
12 Sunderland Hospital, Sunderland, United Kingdom.
13 University College Hospital, London, United Kingdom.
14 Department of Upper Gastrointestinal and Bariatric Surgery, Musgrove Park Hospital, Taunton, United Kingdom.