[1] Univ Calif Irvine, Div Gen Internal Med & Primary Care, Acad 3, Sch Med, Irvine, CA 92697 USA
[2] Univ Calif Irvine, Ctr Hlth Policy Res, Acad 3, Sch Med, Irvine, CA 92697 USA
[3] Harvard Univ, Sch Med, Beth Israel Deaconess Med Ctr, Div Gen Internal Med & Primary Care, Boston, MA USA
[4] Univ Massachusetts, Survey Res Ctr, Boston, MA 02125 USA
[5] Dana Farber Canc Inst, Boston, MA 02115 USA