A Comparison of Plasma Efavirenz and Tenofovir, Dried Blood Spot Tenofovir-Diphosphate, and Self-Reported Adherence to Predict Virologic Suppression Among South African Women

Abstract

Background-Tenofovir-diphosphate (TFV-DP) in dried blood spots (DBS) is an objective longterm adherence measure but data are limited on its ability to predict virologic suppression (VS) in people on antiretroviral (ARV) treatment. There are also no data comparing DBS TFV-DP with plasma ARV concentrations as predictors of VS.Methods-Women who were on a first-line regimen of tenofovir, emtricitabine, and efavirenz (EFV) were enrolled in a cross-sectional study. Plasma EFV and tenofovir (TFV), DBS TFV-DP assays, and 30-day self-reported adherence were evaluated as predictors of VS (<50 copies/mL) with area under the curve (AUC) of receiver operating characteristics (ROC) and logistic regression.Results-We enrolled 137 women; mean age 33 years; median 4 years on ART; 88 (64%) had VS. In ROC analyses: DBS TFV-DP (0.926 [95%CI 0.876-0.976]) had a higher AUC than plasma TFV (0.864 [0.797-0.932]; p=0.006), while plasma EFV (0.903 [0.839-0.967]) was not significantly different from DBS TFV-DP (p=0.138) or plasma TFV (p=0.140

Potential challenges to sustained viral load suppression in the HIV treatment programme in South Africa: a narrative overview

“…A drawback though is that these methods are expensive, in their requirements for equipment and technical personnel. Therefore, point-of-care devices on these approaches are highly desirable [ 42 ].…”

“…The association of EFV, TFV, and DBS TFV-DP were seen as strong predictors of virologic suppression. Data shows that EFV or TFV assays have potential for development as point-of-care assays for use in more objective adherence measurement in resource-limited settings [ 42 ] A validated liquid chromatography tandem mass spectrometry method for the analysis of efavirenz in 0.2 mg hair samples from HIV-infected patients Western Cape Using ten times less hair than in a previously published method, the lower limit of quantitation (LLOQ) was validated at 0.625 ng mg −1 . This paper perhaps reports the first quantitative method for the determination of efavirenz in hair in South Africa.…”

Perspectives on the utility and interest in a point-of-care urine tenofovir test for adherence to HIV pre-exposure prophylaxis and antiretroviral therapy: an exploratory qualitative assessment among U.S. clients and providers

“…In addition, subjective methods used to measure ART and PrEP adherence, such as self-reported adherence, are prone to social desirability bias; while commonly used objective measures, such as pill counts and pharmacy refill records, are often inaccurate and unreliable [14][15][16]. Objective metrics are available to measure adherence through pharmacokinetic analysis of concentrations of tenofovir (TFV), a drug formulation found in oral PrEP regimens and most ART regimens, which is detectable in whole blood, plasma, dried blood spots, cerebrospinal fluid, mucosal fluid, oral tissue, urine, and hair [12,[17][18][19][20][21][22][23][24][25][26][27][28][29][30]. However, widespread implementation of these metrics is limited by its expense, turnaround time, and need for specialized personnel [23,25].…”

“…A common practice of assessing ART adherence is by testing HIV RNA viral load (VL) [ 1 ], but a VL test result is not consistently analogous to recent ART adherence [ 10 , 12 , 13 ]. In addition, subjective methods used to measure ART and PrEP adherence, such as self-reported adherence, are prone to social desirability bias; while commonly used objective measures, such as pill counts and pharmacy refill records, are often inaccurate and unreliable [ 14 – 16 ].…”

“…Real-time measures of TFV may facilitate identification of PLWH or PrEP clients with adherence challenges before adverse clinical outcomes occur [ 12 , 14 , 24 , 25 , 27 , 28 , 31 – 34 ]. Adherence testing has also proven to be more reliable in assessing medication adherence than self-report or electronic monitoring tools [ 12 , 14 ]. Several tests that measure levels of TFV in real time at the point of care are currently in development [ 24 , 25 , 28 , 35 ], and may impact clinical care and patient outcomes.…”