[1] Univ Southern Denmark, Dept Clin Res, Res Unit Gynecol & Obstet, Odense, Denmark
[2] Odense Univ Hosp, Ctr Clin Epidemiol, Odense, Denmark
[3] Univ Southern Denmark, Dept Clin Res, Res Unit Clin Epidemiol, Odense, Denmark
[4] Brigham & Womens Hosp, Dept Med, Div Gastroenterol Hepatol & Endoscopy, 75 Francis St, Boston, MA 02115 USA
[5] Massachusetts, Boston, MA USA
[6] Harvard Med Sch, Boston, MA 02115 USA