1. Department of Internal Medicine, Hanyang University College of Medicine, Seoul, Korea.
2. Department of Internal Medicine, College of Medicine, Ewha Womans University, Seoul, Korea.
3. Department of Allergy and Clinical Immunology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
4. Department of Internal Medicine, Gachon University Gil Medical Center, Incheon, Korea.
5. Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, Korea.
6. Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
7. Department of Internal Medicine, Nowon Eulji Hospital, Eulji University School of Medicine, Seoul, Korea.