1. Department of PediatricsChildren's Hospital of Western Ontario London Ontario Canada
2. Department of Otolaryngology—Head and Neck Surgery, London Health Sciences CenterWestern University London Ontario Canada
3. Department of PediatricsChildren's Hospital of Eastern Ontario Ottawa Ontario Canada
4. Children's Hospital of Eastern Ontario Research Institute Ottawa Ontario Canada
5. Department of Pediatrics, Faculty of MedicineUniversity of Ottawa Ottawa Ontario Canada
6. ICES uOttawa Ottawa Ontario Canada
7. School of Epidemiology and Public HealthUniversity of Ottawa Ottawa Ontario Canada
8. Department of Otolaryngology—Head and Neck SurgeryUniversity of Ottawa Ottawa Ontario Canada