The purpose was to investigate HIV-1 subtype determinants of outcome.

The objectives were:

• To compare responses to each treatment strategy the study, across subtypes
• To assess whether subtype is an independent variable in determining response to therapy
• To assess the impact of viral sub-type on emerging resistance mutations
• To identify baseline mutational associations with failure of specific regimens
• To verify the phenotype of novel mutations

Assesments were part of the main study and all patients included in the main study participated in this ancillary study.