[1] Harvard Univ, Sch Med, Cambridge, MA 02138 USA
[2] Brigham & Womens Hosp, Div Gen Internal Med, Boston, MA 02115 USA
[3] Harvard Univ, Massachusetts Gen Hosp, Inst Hlth Policy, Boston, MA 02114 USA
[4] Brigham & Womens Hosp, Div Gen Med & Primary Care, Boston, MA 02115 USA