[1] Dongguk Univ, Coll Med, Dept Internal Med, Ilsan Hosp, Goyang, South Korea
[2] Seoul Natl Univ Hosp, Ctr Palliat Care & Clin Eth, Seoul, South Korea
[3] Univ Ulsan, Asan Med Ctr, Dept Oncol, Coll Med, Seoul, South Korea
[4] Seoul Natl Univ Hosp, Dept Pediat, Seoul, South Korea
[5] Dongguk Univ, Dept Biostat, Coll Med, Goyang, South Korea
[6] Seoul Natl Univ Hosp, Dept Internal Med, Seoul, South Korea
[7] Univ Ulsan, Asan Med Ctr, Dept Pulm & Crit Care Med, Coll Med, 88 Olymp Ro 43 Gil, Seoul 05505, South Korea