[1] Univ Calif Berkeley, Sch Publ Hlth, Berkeley, CA 94720 USA
[2] Univ Calif Riverside, Sch Med, Riverside, CA 92521 USA
[3] Univ Calif Berkeley, Sch Publ Hlth, Div Epidemiol, Berkeley, CA 94720 USA
[4] Univ Calif Berkeley, Sch Publ Hlth, Div Biostat, Berkeley, CA 94720 USA
[5] London Sch Hyg & Trop Med, Dept Noncommunicable Dis Epidemiol, London, England
[6] Univ Calif San Francisco, Dept Dermatol, Div Epidemiol, 2430 Sutter St,N421, San Francisco, CA 94115 USA