[1] Harvard Univ, Sch Med, Cambridge, MA 02138 USA
[2] Beth Israel Deaconess Med Ctr, Washington, DC USA
[3] Ctr Studying Hlth Syst Change, Washington, DC USA
[4] Inst Hlth Policy, Boston, MA USA
[5] Massachusetts Gen Hosp, Partners HealthCare Syst, Boston, MA 02114 USA