[1] St Michaels Hosp, Li Ka Shing Knowledge Inst, Toronto, ON M5B 1W8, Canada
[2] Univ Toronto, Dept Med, Toronto, ON, Canada
[3] McMaster Univ, Dept Family Med, Hamilton, ON L8S 4L8, Canada
[4] St Josephs Healthcare, Ctr Evaluat Med, Hamilton, ON, Canada
[5] St Josephs Hosp, Program Assessment Technol Hlth PATH Res Inst, Hamilton, ON, Canada
[6] McMaster Univ, Dept Clin Epidemiol & Biostat, Hamilton, ON, Canada
[7] Univ Alberta, Dept Med, Edmonton, AB, Canada
[8] Univ Western Ontario, Dept Epidemiol & Biostat, Schulich Sch Med & Dent, London, ON, Canada