[1] Univ Calif San Francisco, Dept Med, San Francisco, CA USA
[2] Univ Calif San Francisco, Dept Epidemiol & Biostat, San Francisco, CA 94143 USA
[3] San Francisco VA Med Ctr, San Francisco, CA USA
[4] San Francisco Gen Hosp, Dept Med, San Francisco, CA 94110 USA
[5] San Francisco Gen Hosp, Posit Hlth Program, San Francisco, CA 94110 USA
[6] Kaiser Permanente Div Res, Oakland, CA USA