1. Division of Respiratory, Allergy and Critical Care Medicine, Konyang University College of Medicine, Daejeon, Korea.
2. Department of Allergy and Clinical Immunology, Ajou University School of Medicine, Suwon, Korea.
3. Division of Allergy and Immunology, Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea.
4. Division of Respiratory and Critical Care Medicine, Korea University College of Medicine, Seoul, Korea.
5. Division of Pulmonary, Allergy, and Critical Care Medicine, Hallylm University Sacred Heart Hospital, Anyang, Korea.
6. Department of Statistics, Clinical Trial Center, Ajou University Medical Center, Suwon, Korea.