1. Department of Surgery, Goo Hospital, Daegu, Korea.
2. Department of Internal Medicine, School of Medicine, Kyungpook National University, Daegu, Korea.
3. Department of Internal Medicine, Keimyung University School of Medicine, Daegu, Korea.
4. Department of Internal Medicine, Yeungnam University College of Medicine, Daegu, Korea.
5. Department of Medical Statistics, Catholic University of Daegu School of Medicine, Daegu, Korea.