1. Department of Internal Medicine, Institute of Health Science, College of Medicine, Gyeongsang National University, Jinju, South Korea;
2. Department of Internal Medicine, College of Medicine, Dong-A University, Busan, South Korea;
3. Department of Internal Medicine, Sungkyunkwan University Samsung Medical Center, Seoul, South Korea;
4. Department of Internal Medicine, College of Medicine, Chung-Ang University, Seoul, South Korea;
5. Departments of Internal Medicine, Inje University College of Medicine, Ilsan Paik Hospital, Goyang, South Korea;
6. Department of Internal Medicine, College of Medicine, Busan University, Busan, South Korea;
7. Department of Internal Medicine, Sungkyunkwan University Samsung Changwon Hospital, Changwon, South Korea;
8. Department of Internal Medicine, Kyung Hee University Hospital at Gangdong, College of Medicine, Kyung Hee University, Seoul, South Korea;
9. Department of Palliative Care and Rehabilitation Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA