[1] Univ Cambridge, Div Gastroenterol & Hepatol, Dept Med, Cambridge CB2 0QQ, England
[2] Innsbruck Med Univ, Dept Med 2, Innsbruck, Austria
[3] Harvard Univ, Brigham & Womens Hosp, Sch Med, Div Gastroenterol Hepatol & Endoscopy,Dept Med, Boston, MA 02115 USA