1. Department of Internal Medicine, School of Medicine, Gyeongsang National University, Jinju, Korea.
2. Department of Internal Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea.
3. Department of Internal Medicine, College of Medicine, Chung-Ang University, Seoul, South Korea.
4. Department of Palliative Care and Rehabilitation Medicine, University of Texas MD Anderson Cancer Center, Houston, Texas.