1. Department of Otorhinolaryngology-Head and Neck Surgery, Sungkyunkwan University School of Medicine, Samsung Medical Center, Seoul 06351, Republic of Korea
2. Department of Otolaryngology, Ajou University Hospital, Ajou University School of Medicine, Suwon 16499, Republic of Korea
3. Biomedical Statistics Center, Research Institute for Future Medicine, Samsung Medical Center, Seoul 06351, Republic of Korea
4. Department of Otolaryngology, Ulsan University School of Medicine, Asan Medical Center, Seoul 05505, Republic of Korea