Short Communication: Cascade of Antiretroviral Therapy Adherence in Virologically Suppressed Persons Living with HIV.

Variable adherence to antiretroviral therapy (ART) can maintain HIV viral suppression, but our understanding of the ART adherence continuum remains limited. In a clinical cohort of adult persons living with HIV treated with a tenofovir (TFV) disoproxil fumarate/emtricitabine (TDF/FTC)-based regimen, data on 3-month self-reported adherence and dried blood spots (DBS) for TFV diphosphate (TFV-DP) and FTC triphosphate (FTC-TP) were collected. Among 521 participants in whom DBS were available upon enrollment, 333 were virologically suppressed (<20 copies/mL). Only 145 (44%) of them reported 100% 3-month adherence, and 69 (21%) had drug concentrations in the highest adherence categories (TFV-DP ≥1,850 fmol/punch and quantifiable FTC-TP). These findings demonstrate a wide range of ART adherence and drug exposure associated with viral suppression, indicating that modern regimens are pharmacologically forgiving. Additional research is needed to understand the biologic effects of variable adherence and drug exposure beyond plasma virologic suppression.