1. Department of Family Medicine, Chungnam National University Hospital, Daejeon, South Korea.
2. Department of Medicine, Dongguk University-Seoul, Seoul, South Korea.
3. Department of Family Medicine, Dongguk University Ilsan Hospital, Goyang-si, South Korea.
4. Department of Palliative Medicine, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, South Korea.
5. Palliative Care and Hospice Center, Bobath Memorial Hospital, Sungnam, South Korea.
6. Department of Family Medicine, St. Paul's Hospital, College of Medicine, The Catholic University of Korea, Seoul, South Korea.
7. Department of Statistics, Dongguk University-Seoul, Seoul, South Korea.
8. Department of Hemato-oncology, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan, South Korea.
9. Department of Hemato-oncology, Keimyung University Dongsan Hospital, Daegu, South Korea.