In HIV-NAT 013 phase I study, genotyping was performed in 95 children on dual NRTI which showed that almost all children had resistance to NRTi. The HIV-NAT 013 phase II is a follow up study to evaluate treatment outcome after salvage therapy and the evolution of mutations.

The HIV-NAT 013 study (conducted in 2003) evaluated prevalence and pattern of RT mutation in 95 children treated with dual NRTI. The study showed almost all children to have some degree of NRTI resistance and 40% with multi NRTI resistance. The mutation reported was major mutation.

After the study, the patients were managed based on the physician's judgment using genotyping results. The 95 patients in HIV-NAT 013 are categorized into 3 groups.

1. No viral resistance
2. Low grade resistance with or without clinical/ immunological failure
3. High grade resistance with or without clinical/ immunological failure.

There are limited prospective studies evaluating outcome of decision regarding salvage therapy after genotyping results

There are also new mutations that are not considered major mutation that may affect treatment outcome

Knowledge learned from this study will benefit Thai children with NRTI resistance by helping pediatricians better choose salvage treatment options

Inclusion Criteria:

• All children from HIV-NAT 013 phase I

Exclusion Criteria:

• No inform consent obtained