1. Division of Allergy, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
2. Department of Internal Medicine, Veterans Health Service Medical Center, 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, College of Medicine, Ewha Womans University, Seoul, Korea.
5. Department of Internal Medicine, Gachon University Gil Medical Center, Incheon, Korea.
6. Department of Allergy and Clinical Immunology, Kyungpook National University Chilgok Hospital, School of Medicine, Kyungpook National University, Daegu, Korea.
7. Department of Internal Medicine, Pusan National University College of Medicine, Busan, Korea.
8. Department of Internal Medicine, Pusan National University Yangsan Hospital, Yangsan, Korea.
9. Department of Internal Medicine, Hanyang University Hospital, Hanyang University College of Medicine, Seoul, Korea.
10. Department of Internal Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea.
11. Department of Preventive Medicine, University of Ulsan College of Medicine, Seoul, Korea.