Urine tenofovir and dried blood spot tenofovir diphosphate concentrations and viraemia in people taking efavirenz and dolutegravir based antiretroviral therapy.
Dorward J., Govender K., Moodley P., Lessells R., Samsunder N., Sookrajh Y., Fanshawe TR., Turner PJ., Butler CC., Drain PK., Hayward GN., Garrett N.
OBJECTIVE: We aimed to determine whether urine tenofovir (TFV) and dried blood spot (DBS) tenofovir diphosphate (TFV-DP) concentrations are associated with concurrent HIV viraemia. DESIGN: Cross-sectional study among people with HIV (PWH) receiving tenofovir disoproxil fumarate (TDF)-based antiretroviral therapy (ART). METHODS: We used dual tandem liquid chromatography and mass spectrometry to measure urine TFV and DBS TFV-DP concentrations, and evaluated their associations with concurrent viraemia ≥1000 copies/mL using logistic regression models. In exploratory analyses, we used receiver operating curves to estimate optimal urine TFV and DBS TFV-DP thresholds to predict concurrent viraemia. RESULTS: Among 124 participants, 68 (54.8%) were women, median age was 39 years (interquartile range [IQR] 34-45) and 74 (59.7%) were receiving efavirenz versus 50 (40.3%) receiving dolutegravir. Higher concentrations of urine TFV (1000 ng/mL increase, odds ratio [OR] 0.97 95%CI 0.94-0.99, p = 0.005) and DBS TFV-DP (100 fmol/punch increase, OR 0.76, 95%CI 0.67-0.86, p