1. Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 60351, Republic of Korea
2. Department of Internal Medicine, Dongguk University Ilsan Hospital, Dongguk University School of Medicine, Goyang 10326, Republic of Korea
3. Department of Internal Medicine, Ewha Womans University School of Medicine, Seoul 07804, Republic of Korea
4. Department of Internal Medicine, Kyungpook National University Medical Center, Kyungpook National University School of Medicine, Daegu 37224, Republic of Korea