Little is known about what treatment combinations are best for HIV infected children. This study examined the long-term effectiveness of different anti-HIV drug combinations in children and strategies for switching treatment if the first treatment does not work. The study enrolled children who had not previously taken anti-HIV medication. Participants in this study were recruited in the United States, South America and Europe.

Some European children may also enroll in a substudy that will observe changes in body fat in children taking anti-HIV medications.

Antiretroviral therapy in children aims to prolong clinical and immunologic health. Currently, there are no data defining a particular highly active antiretroviral therapy (HAART) strategy as the optimal first-line therapy for children. This study evaluated the long-term efficacy of two HAART regimens used as initial therapy: 1) two nucleoside reverse transcriptase inhibitors (NRTIs) plus a protease inhibitor (PI), and 2) two NRTIs plus a nonnucleoside reverse transcriptase inhibitor (NNRTI). It also evaluated different strategies for switching therapy when the initial regimen fails. The long-term nature of this study should clarify whether early switching of therapy improves immunologic and virologic outcomes, or results in a more rapid exhaustion of treatment options. The study was conducted in the United States and in Europe.

Participants in this study had a CD4 cell count and viral load test during a screening visit. Participants had an entry visit that included blood and urine tests. Participants were then randomly assigned to one of four groups: Groups PI/1K and PI/30K received two NRTIs plus a PI; Groups NNRTI/1K and NNRTI/30K received two NRTIs plus an NNRTI. The medications allowed in the study were: abacavir, didanosine, emtricitabine, emtricitabine/tenofovir disoproxil fumarate, lamivudine, lamivudine/zidovudine, stavudine, tenofovir disoproxil fumarate, zalcitabine, and zidovudine (NRTIs); efavirenz and nevirapine (NNRTIs); efavirenz/emtricitabine/tenofovir disoproxil fumurate (NNRTI/NRTI); and amprenavir,atazanavir, darunavir, fosamprenavir calcium, indinavir, lopinavir/ritonavir, nelfinavir, saquinavir, ritonavir, and tipranavir (PIs). Note: Per the 06/28/05 amendment of this trial, emtricitabine, emtricitabine/tenofovir disoproxil fumarate, and tenofovir dioproxil fumarate were added to the list of medications that could be included in a participant's treatment regimen.

For participants whose initial regimen failed, or who experienced clinical disease progression (indicated by the development of a new CDC Category C diagnosis) or other clinical disease progression at or after Week 24 of first-line therapy, second-line therapy was strongly encouraged. (However, if poor adherence was suspected as a possible reason for an increase in HIV viral load, the site and the clinician were to try to improve patient adherence and obtain additional confirmatory viral load values within a five-week time frame.) In second-line therapy, participants who initially took NRTIs with a PI switched to NRTIs and an NNRTI. Participants who initially took NRTIs and an NNRTI switched to NRTIs and a PI. The timing of the switch was based on the participant's group: Groups PI/1K and NNRTI/1K switched to second-line treatment when viral load was 1,000 copies/ml or greater; Groups PI/30K and NNRTI/30K switched to second-line treatment when viral load was 30,000 copies/ml or greater. Participants who failed second-line therapy discontinued study treatment and were offered the best available therapy at the discretion of the clinician.

Participants had study visits at Weeks 2, 4, 8, 12, 16, 24, and every 12 weeks thereafter until the drug regimen was switched to second-line treatment. Participants then had a re-entry visit and the schedule of visits restarted. Participants were in the study between 4 and 7 years, depending on when they enrolled. All study visits included medical history, a physical exam, and blood collection. Urine collection occurred at most visits. Participants were asked to complete adherence questionnaires and PACTG participants underwent neuropsychological assessments at selected visits.

All participants in this study were encouraged to coenroll in PACTG 219C, Long-Term Effects of HIV Exposure and Infection in Children. Participants in the European portion of the study may be asked to enroll in a substudy to observe the development and progression of lipodystrophy syndrome in children.

Inclusion Criteria:

• Older than 30 days and younger than 18 years of age (may enroll up to the day before their 18th birthday)
• HIV infected
• Not previously on HAART or received anti-HIV drugs for less than 56 consecutive days after birth to prevent mother-to-infant HIV transmission. Participants who have previously received nevirapine for the prevention of mother-to-infant HIV transmission are not eligible for this study.
• Willing to use acceptable methods of contraception

Exclusion Criteria:

• Grade 3 or 4 clinical or laboratory toxicity. More information on this criterion can be found in the protocol.
• Active opportunistic infection or a serious bacterial infection at the time of study entry
• Pancreas, nervous system, blood, liver, or kidney problems that make it impossible to take study medications
• Taking any medication that cannot be combined with the study medications in first-line therapy
• Received therapy for cancer
• Pregnant or breastfeeding