1. Department of Otolaryngology, Tokyo Teishin Hospital, Tokyo, Japan
2. Department of Otolaryngology and Head and Neck Surgery, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
3. Biostatistics Division, Clinical Research Support Center, The University of Tokyo Hospital, Tokyo, Japan
4. Department of Otolaryngology, Teikyo University School of Medicine Mizonokuchi Hospital, Kawasaki, Japan