1. Division of Otolaryngology-Head and Neck Surgery ; Intermountain Healthcare; Salt Lake City Utah U.S.A
2. Division of Epidemiology ; Intermountain Healthcare; Salt Lake City Utah U.S.A
3. University of Utah School of Medicine ; Salt Lake City Utah U.S.A
4. Department of Pediatrics ; Intermountain Healthcare; Salt Lake City Utah U.S.A
5. Institute for Health Care Delivery Research , Intermountain Healthcare; Salt Lake City Utah U.S.A