[1] Univ Calif Los Angeles, Dept Psychiat, Hlth Risk Reduct Projects, Los Angeles, CA 90025 USA
[2] Westat Corp, Rockville, MD USA
[3] Univ Alabama, Dept Epidemiol & Int Hlth, Birmingham, AL USA
[4] Montefiore Med Ctr, Dept Pediat, Adolescent AIDS Program, Bronx, NY 10467 USA