1. Department of Surgery, University of Toronto , 149 College Street, Toronto, ON M5T 1P5, Canada
2. Division of General Surgery, Toronto Western Hospital, University Health Network , 399 Bathurst St, Toronto, ON M5T 2S8, Canada
3. Health Quality Ontario, Ontario Health , 130 Bloor Street West, Toronto, ON M5S 1N5, Canada
4. Clinical Epidemiology Program, The Ottawa Hospital Research Institute , 1053 Carling Ave, Ottawa, ON K1Y 4E9, Canada
5. Department of Otolaryngology-Head and Neck Surgery, University of Ottawa , 75 Laurier Ave. E, Ottawa, ON K1N 6N5, Canada