1. Department of Internal Medicine, Soonchunhyang University Cheonan Hospital, Cheonan, Republic of Korea.
2. Department of Internal Medicine, Soonchunhyang University Bucheon Hospital, Bucheon, Republic of Korea.
3. Department of Internal Medicine, Soonchunhyang University Seoul Hospital, Seoul, Republic of Korea.
4. Department of Internal Medicine, Kyung Hee University Hospital, Seoul, Republic of Korea.
5. Department of Internal Medicine, Dongguk University Ilsan Hospital, Goyang, Republic of Korea.