Model influence diagram.

Within each therapy line, the choice of ART regimen determines virologic response and drug costs. Virologic response, in turn, influences the evolution of HIV-1 RNA viral load and CD4+ T cell counts over time. Health care costs and QALY, through QoL and mortality, are dependent on CD4+ T cell counts. For first-line therapy, differential adherence between STR and MTR further influences virologic response and drug costs.