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Background Food insecurity has been linked to suboptimal antiretroviral therapy (ART) adherence in persons with HIV (PWH). This association has not been evaluated using tenofovir diphosphate (TFV-DP) in dried blood spots (DBSs), a biomarker of cumulative ART adherence and exposure. Methods Within a prospective South African cohort of treatment-naive PWH initiating ART, a subset of participants with measured TFV-DP in DBS values was assessed for food insecurity status. Bivariate and multivariate median-based regression analysis compared the association between food insecurity and TFV-DP concentrations in DBSs adjusting for age, sex, ethnicity, medication possession ratio (MPR), and estimated glomerular filtration rate. Results Drug concentrations were available for 285 study participants. Overall, 62 (22%) PWH reported worrying about food insecurity and 44 (15%) reported not having enough food to eat in the last month. The crude median concentrations of TFV-DP in DBSs differed significantly between those who expressed food insecurity worry versus those who did not (599 [interquartile range {IQR}, 417–783] fmol/punch vs 716 [IQR, 453–957] fmol/punch; P =.032). In adjusted median-based regression, those with food insecurity worry had concentrations of TFV-DP that were 155 (95% confidence interval, −275 to −35; P =.012) fmol/punch lower than those who did not report food insecurity worry. Age and MPR remained significantly associated with TFV-DP. Conclusions In this study, food insecurity worry is associated with lower TFV-DP concentrations in South African PWH. This highlights the role of food insecurity as a social determinant of HIV outcomes including ART failure and resistance. [ABSTRACT FROM AUTHOR]

Introduction: Tenofovir diphosphate (TFV‐DP) in dried blood spots (DBS), a measure of cumulative antiretroviral therapy (ART) adherence, is associated with viral suppression and predicts future viremia in persons with HIV (PWH). However, its utility to identify those at risk for virologic failure (VF) and drug resistance is unknown. To address this, we aimed to establish the association between this adherence biomarker and VF with drug resistance in a cohort of PWH initiating first‐line ART in KwaZulu‐Natal, South Africa. Methods: PWH initiating TFV disoproxil fumarate (TDF)‐based ART within a parent prospective cohort were evaluated. Using a nested design, DBS for TFV‐DP were collected from cases who developed VF (HIV‐1 RNA ≥1000 copies/ml) after ≥5 months on ART versus controls, matched 1:2 by site, age, gender, race and ART duration. Cases were categorized as having VF with or without resistance using genotyping. One‐way analysis of variance (ANOVA) was used to compare TFV‐DP for controls, cases with VF and resistance, and cases with VF without resistance. Data are presented as mean (standard deviation, SD) or geometric mean [95% confidence interval, 95% CI]. Results and discussion: One thousand participants were enrolled in the parent study between 2014 and 2016, of which 288 (29%) had DBS available. Of these, 94 (33%) were cases and 194 (67%) were controls; 59% were women. Mean age of our population was 33 (SD 8) years. Genotyping was available in 50 (53%) of the 94 cases. Geometric mean TFV‐DP in DBS from controls was 708 [95% CI; 647–773] fmol/punch, which was higher compared to participants having VF with resistance (n = 36), 386 [95% CI; 241–617] fmol/punch and VF without resistance (n = 14), 61 [95% CI; 22–164] fmol/punch; p<0.001. Genotype could not be obtained in 44 (47%) cases. Conclusions: TFV‐DP in DBS showed a stepwise association with VF and drug resistance in South African PWH. Participants having VF with resistance had mid‐range concentrations of TFV‐DP, which were higher than those for PWH without resistance. Future research on the clinical utility of TFV‐DP concentrations in DBS to predict and prevent the development of VF and drug resistance is needed. [ABSTRACT FROM AUTHOR]