[1] Univ Toronto, Dept Surg, 149 Coll St, Toronto, ON M5T 1P5, Canada
[2] Univ Hlth Network, Toronto Western Hosp, Div Gen Surg, 399 Bathurst St, Toronto, ON M5T 2S8, Canada
[3] Ontario Hlth, Hlth Qual Ontario, 130 Bloor St West, Toronto, ON M5S 1N5, Canada
[4] Ottawa Hosp, Clin Epidemiol Program, Res Inst, 1053 Carling Ave, Ottawa, ON K1Y 4E9, Canada
[5] Univ Ottawa, Dept Otolaryngol Head & Neck Surg, 75 Laurier Ave E, Ottawa, ON K1N 6N5, Canada