[1] Sungkyunkwan Univ, Kangbuk Samsung Hosp, Dept Family Med, Sch Med, 29 Saemunan Ro, Seoul 03181, South Korea
[2] Sungkyunkwan Univ, Ctr Cohort Studies, Total Healthcare Ctr, Kangbuk Samsung Hosp,Sch Med, Seoul, South Korea
[3] Sungkyunkwan Univ, Kangbuk Samsung Hosp, Dept Occupat & Environm Med, Sch Med, Samsung Main Bldg B2,250 Taepyung Ro 2ga, Seoul 04514, South Korea
[4] Sungkyunkwan Univ, Dept Clin Res Design & Evaluat, SAIHST, Seoul, South Korea
[5] Sungkyunkwan Univ, Kangbuk Samsung Hosp, Div Gastroenterol, Dept Internal Med,Sch Med, Seoul, South Korea