[1] Pusan Natl Univ, Childrens Hosp, Coll Med, Dept Pediat, Yangsan, South Korea
[2] Chungbuk Natl Univ, Coll Med, Dept Pediat, Cheongju, South Korea
[3] Univ Ulsan, Gangneung Asan Hosp, Coll Med, Dept Pediat, Kangnung, South Korea
[4] Gyeongsang Natl Univ, Gyeongsang Natl Univ Hosp, Gyeongsang Inst Sci, Sch Med,Dept Pediat, 15 Jinju Daero 816beon Gil, Jinju 52727, South Korea
[5] Catholic Univ Korea, Seoul St Marys Hosp, Coll Med, Dept Occupat & Environm Med, Seoul St, Seoul, South Korea
[6] Pusan Natl Univ, Yangsan Hosp, Dept Surg, Div Gastrointestinal Surg, Yangsan, South Korea