[1] Univ Calif San Francisco, Dept Family & Community Med, San Francisco, CA 94143 USA
[2] RAND Corp, Santa Monica, CA USA
[3] Univ Calif Los Angeles, Robert Wood Johnson Clin Scholars Program, Los Angeles, CA USA
[4] Univ Calif Los Angeles, Div Gen Internal Med & Hlth Serv Res, Los Angeles, CA USA