What percent or nummerical increase in viral load count while on an existing drug regimen is an indicator that a change in drug combinations is advised?

In someone who is clinically stable (no concurrent illnesses, recent vaccinations) and is adherent to the regimen, a 3 fold (0.5 log) consistent increase (two separate measurements) from the nadir, would be considered virologically significant. Additionally, if the viral load were undetectable (at <50/ml) and is now detectable, say 200 or more, that would also be significant. However, depending on the circumstances, a change in therapy may or may not be advised. If someone were heavily antiretroviral experienced, with few remaining options, and who had a significant CD4 increase or continuing increase in the face of a now detectable viral load, one might opt to wait before changing. If someone were failing their first regimen and viral load had now rebounded, earlier rather than later intervention would be advisable.

MH