[1] Univ Toronto, St Michaels Hosp, Dept Med, Toronto, ON M5B 1W8, Canada
[2] Univ Toronto, St Michaels Hosp, Dept Obstet & Gynecol, Toronto, ON M5B 1W8, Canada
[3] Univ Toronto, St Michaels Hosp, Dept Hlth Policy Management & Evaluat, Toronto, ON M5B 1W8, Canada
[4] McMaster Univ, Hamilton Gen Hosp, Populat Hlth Res Inst, Hamilton, ON, Canada
[5] McMaster Univ, Hamilton Gen Hosp, Dept Med, Hamilton, ON, Canada
[6] Hamilton Hlth Sci, Div Cardiol, Dept Med, Hamilton, ON, Canada
[7] Henderson Res Ctr, Hamilton, ON, Canada