[1] McGill Univ, Div Clin Epidemiol, Res Inst, Ctr Hlth, Montreal, PQ H3A 1A1, Canada
[2] Univ Calif San Francisco, San Francisco, CA 94143 USA
[3] Univ Western Ontario, London, ON, Canada
[4] Univ Calgary, Calgary, AB, Canada
[5] Univ Manitoba, Winnipeg, MB, Canada
[6] Univ Alberta, Edmonton, AB, Canada
[7] Univ Saskatchewan, Regina, SK, Canada
[8] Univ Montreal, Montreal, PQ, Canada
[9] Dalhousie Univ, Halifax, NS, Canada