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