• Clinical, immunologic and virologic outcome of children who had genotyping directed salvage therapy [ Time Frame: 1 time point (Cross Sectional Study) ]
  

• Comparison outcome of children in the 3 groups, [ Time Frame: 1 time point ]
  
• Changes of mutation in children within the 3 groups, and [ Time Frame: 1 time point ]
  
• Effect of previously unreported mutations, minor and others, on treatment outcome [ Time Frame: 1 time point ]
  

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