Background:  The Centers for Disease and Prevention (CDC) instituted a new cohort study in HIV-infected subjects from birth through 24 years of age as of 2004 to describe clinical and psychosocial aspects of HIV infection.

Methods:  Using a population-proportional-to-size sampling method, 22 hospital and clinic sites were selected. This observational longitudinal cohort study is limited to HIV-infected subjects from birth to 25 years of age at enrollment in 7 U.S. states. We included subjects with ≥1 abstracted clinic visit during or after 2006 in this analysis.

Results:  As of July 31, 2007, 1480 HIV-infected (68.5%) of approximately 2160 eligible youth had been enrolled and met inclusion criteria, including 791 (53.4%) females, 1021 (69%) non-Hispanic blacks, and 343 (23.2%) Hispanics. Participants were nearly equally divided into 3 age groups (years) <13 (34%), 12 to 18 (36%), and 19 to 25 (29%) and had an overall median age of 14.8 years. Their mode of HIV transmission was classified as perinatal (70.3%), behavioral (12.4%), and other (transfusion, transplant, breastfeeding, sexual abuse) (17.3%); with respective median ages (years) of 13.2, 21.8, and 16.4. Most subjects (77%) were being treated with ART, mainly protease inhibitor (PI) -based regimens (52.6%), however perinatal subjects were twice as likely to be on ART as behavioral subjects (p <0.001). Overall, 32% of subjects had an HIV viral load <400 copies/mL and 40% had a viral load <400 to 100,000 copies/mL. While perinatal subjects were about twice as likely to have a viral load <400 copies/mL and no immunosuppression as behavioral subjects, they were also 1.5 times as likely to have severe immunosuppression (p = 0.03) and 3.6 times as likely to have an AIDS-defining condition during their last visit (p = 0.0006). Fewer than 10% of subjects had a viral load ≥100,000 copies/mL (range 7.2% to 9.7%). Sex was discussed by health care providers with 65.5% of subjects ≥13 years of age; 23.1% of these subjects reported being sexually active in 2006 to 2007; behavioral subjects were 3 times as likely as perinatal subjects to be sexually active (p <<0.01).

Conclusions:  Most LEGACY subjects were ≥13 years of age, receiving ART (mainly PI-based HAART), and experiencing no or moderate immunosuppression, viral loads <10,000 copies/mL, and a lack of AIDS-defining conditions. A significant proportion of all subjects ≥13 years of age reported being sexually active. Urgent follow-up is recommended to prevent secondary HIV transmission from this population.