[1] Univ Western Ontario, Dept Med, London, ON, Canada
[2] Univ Western Ontario, Dept Epidemiol & Biostat, London, ON, Canada
[3] McMaster Univ, Dept Clin Epidemiol & Biostat, Hamilton, ON, Canada
[4] SUNY Buffalo, Dept Med, Buffalo, NY 14260 USA
[5] SUNY Buffalo, Dept Family Med, Buffalo, NY 14260 USA
[6] Sunnybrook Hlth Sci Ctr, Dept Med, Toronto, ON M4N 3M5, Canada
[7] Univ Ottawa, Dept Med, Ottawa, ON, Canada
[8] McMaster Univ, Dept Med, Hamilton, ON, Canada
[9] McMaster Univ, Dept Obstet & Gynaecol, Hamilton, ON, Canada
[10] Univ Alberta, Dept Mental Med & Obstretr & Gynecol, Edmonton, AB T6G 2M7, Canada