[1] Milton Keynes Univ Hosp, Milton Keynes MK6 5LD, Bucks, England
[2] Univ Oxford, OUCAGS, Oxford OX3 9DU, England
[3] Pennine Acute Hosp NHS Trust, Sect Inflammatory Bowel Dis, Manchester BL9 7TD, Lancs, England
[4] Univ Manchester, Manchester Acad Hlth Sci, Manchester M13 9NQ, Lancs, England