[1] Univ Calif San Francisco, Dept Emergency Med, 1001 Potrero Ave,Bldg 5,Suite 6A, San Francisco, CA 94110 USA
[2] Univ Calif San Francisco, Dept Neurol, San Francisco, CA 94110 USA
[3] Univ Calif San Francisco, Sch Med, San Francisco, CA 94110 USA
[4] San Francisco State Univ, San Francisco, CA USA
[5] Univ Calif San Francisco, Dept Med & Epidemiol & Biostat, San Francisco, CA 94110 USA