[1] Sungkyunkwan Univ, Sch Med, Kangbuk Samsung Hosp, Div Gastroenterol,Dept Internal Med, Seoul 110746, South Korea
[2] Kyung Hee Univ, Dept Internal Med, Sch Med, Seoul, South Korea
[3] Soonchunhyang Univ, Coll Med, Dept Internal Med, Cheonan, South Korea
[4] Soonchunhyang Univ, Coll Med, Dept Prevent Med, Cheonan, South Korea
[5] Hanyang Univ, Dept Internal Med, Sch Med, Seoul 133791, South Korea
[6] Catholic Univ Korea, Dept Internal Med, Sch Med, Seoul, South Korea
[7] Dankook Univ, Coll Med, Dept Internal Med, Cheonan, South Korea