[1] Natl Hlth Insurance Serv Ilsan Hosp, Dept Internal Med, Div Gastroenterol, Goyang 10444, South Korea
[2] Chungbuk Natl Univ, Dept Internal Med, Coll Med, Cheongju 28644, South Korea
[3] Hallym Univ, Coll Med, Dept Internal Med, Div Gastroenterol,Dongtan Sacred Heart Hosp, Hwaseong 18450, South Korea
[4] Natl Hlth Insurance Serv Ilsan Hosp, Dept Policy Res Affairs, Goyang 10444, South Korea