[1] Univ Calif San Francisco, Sch Med, 513 Parnassus Ave, San Francisco, CA 94143 USA
[2] Univ Calif San Francisco, Dept Obstet Gynecol & Reprod Sci, 550 16th St, San Francisco, CA 94158 USA
[3] Univ Calif San Francisco, Dept Social & Behav Sci, 3333 Calif St, San Francisco, CA 94118 USA
[4] San Francisco Dept Publ Hlth, Populat Hlth Div, 25 Van Ness Ave,Suite 500, San Francisco, CA 94102 USA
[5] St James Infirm, 234 Eddy St, San Francisco, CA 94102 USA
[6] San Francisco VA Med Ctr, Dept Med, Div Gen Internal Med, 4150 Clement St,Bldg 18,Room 111A1, San Francisco, CA 94121 USA