1. Seattle, Washington, Dallas, Texas, Aurora, Colorado, and Boston, Massachusetts
2. Department of Otolaryngology-Head and Neck Surgery, University of Washington School of Medicine, Health Service Research & Development Service, VA Puget Sound Health Care System, Seattle, WA, Department of Health Services, University of Washington, Tenet Health System, Dallas, TX, University of Colorado Health Outcomes Program, and Department of Surgery, VA Boston Healthcare System and Brigham and Women's Hospital, Harvard Medical School.