1. Institute of Allergy and Clinical Immunology, Seoul National University Medical Research Center, Seoul, Korea.
2. Department of Internal Medicine, Chungbuk National University Hospital, Cheongju, Korea.
3. Department of Internal Medicine, Busan Paik Hospital, Inje University College of Medicine, Busan, Korea.
4. Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea.
5. Department of Internal Medicine, Kyungpook National University School of Medicine, Daegu, Korea.
6. Department of Internal Medicine, Pusan National University Hospital, Busan, Korea.
7. Department of Internal Medicine, Pusan National University Yangsan Hospital, Yangsan, Korea.
8. Department of Internal Medicine, Kangwon National University School of Medicine, Chuncheon, Korea.
9. Department of Internal Medicine, Gacheon University Gil Medical Center, Incheon, Korea.
10. Department of Internal Medicine, Haeundae Paik Hospital, Inje University College of Medicine, Busan, Korea.
11. Department of Internal Medicine, Jeju National University School of Medicine, Jeju, Korea.
12. Department of Internal Medicine, Dankook University College of Medicine, Cheonan, Korea.
13. Department of Internal Medicine, Cheonnam National University Hospital, Gwangju, Korea.