[1] Cincinnati Childrens Hosp Med Ctr, Cincinnati, OH 45229 USA
[2] Univ Cincinnati, Coll Med, Cincinnati, OH 45221 USA
[3] Westat Corp, Rockville, MD USA
[4] Eunice Kennedy Shriver Natl Inst Child Hlth & Hum, Pediat Adolescent & Maternal AIDS Branch, NIH, Rockville, MD USA
[5] NYU, Sch Med, New York, NY USA
[6] Univ Alabama Birmingham, Sch Publ Hlth, Birmingham, AL USA
[7] Thomas Jefferson Univ, Jefferson Med Coll, Philadelphia, PA 19107 USA