[1] Chungnam Natl Univ, Sch Med, Dept Family Med, Daejeon, South Korea
[2] Dongguk Univ, Ilsan Hosp, Dept Family Med, Goyang, South Korea
[3] Dongguk Univ, Sch Med, Dept Med, Seoul, South Korea
[4] Catholic Kwandong Univ, Int St Marys Hosp, Dept Family Med, Incheon, South Korea
[5] Bobath Hosp, Dept Internal Med, Seongnam, South Korea
[6] Seoul Natl Univ, Bundang Hosp, Dept Internal Med, Seongnam, South Korea
[7] Yonsei Univ, Coll Med, Dept Internal Med, Div Med Oncol, Seoul, South Korea
[8] Natl Hlth Insurance Serv Ilsan Hosp, Dept Family Med, Goyang, South Korea
[9] Hallym Univ, Kangdong Sacred Heart Hosp, Dept Internal Med, Seoul, South Korea
[10] Pusan Natl Univ, Yangsan Hosp, Dept Internal Med, Pusan, South Korea
[11] Samsung Med Ctr, Dept Family Med, Support Care Ctr, Seoul, South Korea
[12] Dongguk Univ, Dept Stat, Seoul, South Korea
[13] Univ Texas MD Anderson Canc Ctr, Div Canc Med, Dept Palliat Care & Rehabil Med, Houston, TX 77030 USA