1. Department of Internal Medicine, Chungnam National University Hospital, Daejeon, Korea.
2. Department of Internal Medicine, Soonchunhyang University Hospital, Cheonan, Korea.
3. Department of Internal Medicine, Daejeon St Mary's Hospital, Daejeon, Korea.
4. Department of Internal Medicine, Konyang University Hospital, Daejeon, Korea.
5. Department of Internal Medicine, Eulji University Hospital, Daejeon, Korea.