1. Department of Otolaryngology-Head and Neck Surgery; Oregon Health and Science University; Portland Oregon
2. Department of Otolaryngology-Head and Neck Surgery; University of Washington; Seattle Washington
3. Department of Public Health and Preventive Medicine; Division of Biostatistics; Oregon Health and Science University; Portland Oregon
4. Oregon Institute of Occupational Health Sciences; Oregon Health and Science University; Portland Oregon U.S.A