1. Department of Otorhinolaryngology, Kanagawa Children’s Medical Center, Yokohama, Japan
2. Department of Biostatistics, Yokohama City University School of Medicine, Yokohama, Japan
3. Department of Otorhinolaryngology, Minamikase E.N.T. Clinic, Kawasaki, Japan
4. Department of Otorhinolaryngology, Yokohama Medical and Welfare Center Konan, Yokohama, Japan
5. Department of Otorhinolaryngology, International University of Health and Welfare, Mita Hospital, Tokyo, Japan
6. Department of Otorhinolaryngology, Head and Neck Surgery, Yokohama City University Hospital, Yokohama, Japan