[1] St Michaels Hosp, Ctr Res Inner City Hlth, Toronto, ON M5B 1W8, Canada
[2] Harvard Univ, Sch Publ Hlth, Dept Soc Human Dev & Hlth, Boston, MA 02115 USA
[3] Harvard Univ, Sch Med, Dept Hlth Care Policy, Boston, MA 02115 USA
[4] Brigham & Womens Hosp, Div Gen Internal Med, Boston, MA 02115 USA
[5] Harvard Univ, Sch Med, Dept Med, Boston, MA 02115 USA
[6] Dana Farber Canc Inst, Ctr Community Based Res, Boston, MA 02115 USA