Tenofovir diphosphate concentrations in dried blood spots predict future HIV suppression but not virologic failure in adolescents with HIV.

We investigated whether tenofovir diphosphate (TFV-DP) concentration in dried blood spot (DBS) predicted future virologic outcome. Of 52 adolescents with HIV, 46% had virologic suppression, and 44% had virologic failure. TFV-DP concentration in DBS was associated with virologic suppression but not virologic failure. Twenty-six percentage of participants with virologic failure had high levels of antiretroviral adherence at earlier visits. Virologic failure in the setting of high adherence may suggest the presence of HIV drug resistance.