[1] Harvard Med Sch, Brighamand Womens Hosp, Dept Med, Div Gastroenterol Hepatol & Endoscopy, Boston, MA 02115 USA
[2] Odense Univ Hosp, Ctr Clin Epidemiol, Odense, Denmark
[3] Univ Southern Denmark, Dept Clin Res, Res Unit Clin Epidemiol, Odense, Denmark
[4] Tufts Univ, Div Gastroenterolgy & Hepatol, Sch Med, Boston, MA USA
[5] Odense Univ Hosp, Dept Med Gastroenterol S, Odense, Denmark
[6] Univ Southern Denmark, Dept Clin Res, Res Unit Med Gastroenterol, Odense, Denmark