[1] Univ Toronto, Factor Inwentash Fac Social Work, 246 Bloor St W, Toronto, ON M5S 1V4, Canada
[2] Western Univ, Sch Kinesiol, London, ON, Canada
[3] Johns Hopkins Univ, Johns Hopkins Bloomberg Sch Publ Hlth, Dept Populat Family & Reprod Hlth, Baltimore, MD USA
[4] Univ Texas Hlth Sci Ctr Houston, Dept Management Policy & Community Hlth, Houston, TX USA
[5] Univ Calif San Francisco, Dept Pediat, San Francisco, CA USA