[1] Univ Calif San Francisco, Philip R Lee Inst Hlth Policy Studies, 3333 Calif St,Ste 265,POB 0936, San Francisco, CA 94118 USA
[2] Univ Calif San Francisco, Ctr Healthcare Value, 3333 Calif St,Ste 265,POB 0936, San Francisco, CA 94118 USA
[3] Univ Calif San Francisco, Dept Neurosurg, 3333 Calif St,Ste 265,POB 0936, San Francisco, CA 94118 USA
[4] Univ Calif Berkeley, Univ Calif San Francisco, Dept Med, Joint Med Program, Berkeley, CA 94720 USA
[5] Univ Calif San Francisco, Dept Pediat, 3333 Calif St,Ste 265,POB 0936, San Francisco, CA 94118 USA
[6] Univ Calif San Francisco, Dept Med, 3333 Calif St,Ste 265,POB 0936, San Francisco, CA 94118 USA
[7] Univ Calif San Francisco, Dept Emergency Med, 3333 Calif St,Ste 265,POB 0936, San Francisco, CA 94118 USA
[8] Harvard Univ, Sch Med, Dept Hlth Care Policy, Boston, MA 02115 USA
[9] Univ Calif San Francisco, Dept Epidemiol & Biostat, 3333 Calif St,Ste 265,POB 0936, San Francisco, CA 94118 USA