[1] Univ Ulsan, Asan Med Ctr, Dept Internal Med, Div Gastroenterol,Coll Med, Seoul, South Korea
[2] Univ Ulsan, Asan Med Ctr, Dept Clin Epidemiol & Biostat, Coll Med, Seoul, South Korea
[3] Univ Ulsan, Digest Dis Res Ctr, Asan Med Ctr, Div Gastroenterol,Dept Internal Med,Coll Med, 88 Olymp Ro 43 Gil, Seoul 05505, South Korea