[1] Univ Mayor, Ctr Invest Soc & Salud, Nucleo Milenio Sociomed, Santiago, Chile
[2] Univ Mayor, Escuela Salud Publ, Santiago, Chile
[3] Univ Calif San Diego, San Diego State Univ, Joint Doctoral Program Publ Hlth Epidemiol, San Diego, CA USA
[4] Univ Calif San Francisco, Dept Epidemiol & Biostat, 550 16th St,2556, San Francisco, CA 94158 USA