[1] Univ Toronto, St Michaels Hosp, Div Gastroenterol, Toronto, ON, Canada
[2] Univ Calgary, Cumming Sch Med, Dept Oncol, Calgary, AB, Canada
[3] Alberta Hlth Serv, Dept Canc Epidemiol & Prevent Res, Canc Control Alberta, Calgary, AB, Canada
[4] McMaster Univ, Dept Med, Div Gastroenterol, Hamilton, ON, Canada
[5] McMaster Univ, Farncombe Family Digest Hlth Res Inst, Hamilton, ON, Canada
[6] Queens Univ, Fac Hlth Sci, Sch Med, Kingston, ON, Canada
[7] Alberta Hlth Serv, Knowledge Resource Serv, Calgary, AB, Canada
[8] Univ Calgary, Dept Community Hlth Sci, Calgary, AB, Canada
[9] Univ Calgary, Dept Med, Div Gastroenterol & Hepatol, Calgary, AB, Canada
[10] Univ Toronto, Li Ka Shing Knowledge Inst, Dept Med, Toronto, ON, Canada