[1] Western Gen Hosp, Gastrointestinal Unit, Edinburgh EH4 2XU, Midlothian, Scotland
[2] Royal Coll Physicians, Clin Effectiveness & Evaluat Unit, London NW1 4LE, England
[3] Crohns & Colitis UK, St Albans, England
[4] Univ Liverpool, Dept Gastroenterol, Liverpool L69 3BX, Merseyside, England