[1] Harvard Med Sch, Dept Emergency Med, Boston, MA 02115 USA
[2] Brigham & Womens Hosp, 75 Francis St, Boston, MA 02115 USA
[3] Harvard Med Sch, Dept Hlth Care Policy, Boston, MA 02115 USA
[4] Univ Penn, Dept Med Eth & Hlth Policy, Perelman Sch Med, Philadelphia, PA 19104 USA
[5] Univ Penn, Wharton Sch, Dept Hlth Care Management, Philadelphia, PA 19104 USA