1. Department of Pediatrics, Incheon St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.
2. Department of Biostatistics, College of Medicine, The Catholic University of Korea, Seoul, Korea.
3. Department of Statistics and Actuarial Science, College of Natural Sciences, Soongsil University, Seoul, Korea.
4. Department of Pediatrics, St. Vincent’s Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.
5. Department of Pediatrics, Seoul St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.