1. Department of Pediatrics, School of Medicine, The Catholic University of Korea, Bucheon St. Mary’s Hospital, Bucheon, Korea;
2. Department of Pediatrics, Seoul National University College of Medicine, Seoul, Korea;
3. Department of Pediatrics, Korea University College of Medicine, Seoul, Korea;
4. Department of Pediatrics, Hallym University Kangdong Sacred Heart Hospital, Seoul, Korea;
5. Department of Pediatrics, Soonchunhyang University School of Medicine, Bucheon, Korea;
6. Department of Pediatrics, Korea University Anam Hospital, Seoul, Korea;
7. Department of Pediatrics, Seoul National University Bundang Hospital, Seongnam, Korea;
8. Department of Pediatrics, National Health Insurance Service Ilsan Hospital, Ilsan, Korea;
9. Department of Pediatrics, Pediatric Allergy and Respiratory Center, Soonchunhyang University College of Medicine, Seoul, Korea;
10. Department of Pediatrics, Chonnam National University Hospital, Chonnam National University Medical School, Gwangju, Korea;
11. Department of Pediatrics, Dankook University Hospital, Cheonan, Korea;
12. Department of Pediatrics, College of Medicine, Chungbuk National University, Cheongju, Korea;
13. Department of Pediatrics, Pusan National University Yangsan Hospital, Yangsan, Korea;
14. Department of Pediatrics, Gangnam CHA Medical Center CHA University School of Medicine, Seoul, Korea;
15. Department of Pediatrics, Samsung Changwon Hospital, Sungkyunkwan University School of Medicine, Changwon, Korea;
16. Department of Pediatrics, Mediplex Sejong Hospital, Incheon, Korea;
17. Department of Pediatrics, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea;
18. Department of Clinical Epidemiology and Biostatistics, Asan Medical Center, Seoul, Korea;
19. Department of Statistics, Asan Institute for Life Sciences, University of Ulsan College of Medicine, Seoul, Korea;
20. Department of Pediatrics, Inje University Seoul Paik Hospital, Seoul, Korea;
21. Department of Pediatrics, School of Medicine, Inha University, Incheon, Korea;
22. Department of Pediatrics, School of Medicine, The Catholic University of Korea, Uijeongbu St. Mary’s hospital, Uijeongbu, Korea;
23. Division of Allergy and Chronic Respiratory Diseases, Center for Biomedical Sciences, Korea National Institute of Health, Korea Centers for Disease Control and Prevention, Osong, Korea