1 Department of Allergy and Clinical Immunology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
2 Department of Internal Medicine, Korean Armed Forces Capital Hospital, Seongnam, Korea.
3 Department of Internal Medicine, Konkuk University College of Medicine, Seoul, Korea.
4 Department of Internal Medicine, Inje University Haeundae Paik Hospital, Inje University College of Medicine, Busan, Korea.
5 Department of Pulmonary, Allergy and Critical Care Medicine, Kyung Hee University Hospital at Gangdong, College of Medicine, Kyung Hee University, Seoul, Korea.
6 Harvard School of Public Health, Boston, MA, USA.
7 Department of Allergy and Clinical Immunology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea. tbkim@amc.seoul.kr.