Point-of-Care Test for Assessing Tenofovir Adherence: Feasibility and Recommendations from Women in an Oral PrEP Program in Kenya and Their Healthcare Providers

Urine tenofovir testing for real-time PrEP adherence feedback: a qualitative study involving transgender women in Uganda

INTRODUCTION

Adherence counselling with point-of-care (POC) drug-level feedback using a novel tenofovir assay may support pre-exposure prophylaxis (PrEP) adherence; however, perceptions of urine testing and its impact on adherence are not well studied. We qualitatively examined how POC tenofovir testing was experienced by transgender women (TGW) in Uganda.

METHODS

Within a cluster randomized trial of peer-delivered HIV self-testing, self-sampling for sexually transmitted infections and PrEP among HIV-negative TGW showing overall low PrEP prevention-effective adherence (NCT04328025), we conducted a nested qualitative sub-study of the urine POC assay among a random sample of 30 TGW (August 2021-February 2022). TGW interviews explored: (1) experiences with POC urine tenofovir testing and (2) perceptions of PrEP adherence counselling with drug-level feedback. We used an inductive content analytic approach for analysis.

RESULTS

Median age was 21 years (interquartile range 20-24), and 70% engaged in sex work. Four content categories describe how TGW experienced POC urine tenofovir testing: (1) Urine tenofovir testing was initially met with scepticism: Testing urine to detect PrEP initially induced anxiety, with some perceptions of being intrusive and unwarranted. With counselling, however, participants found POC testing acceptable and beneficial. (2) Alignment of urine test results and adherence behaviours: Drug-level feedback aligned with what TGW knew about their adherence. Concurrence between pill taking and tenofovir detection in urine reinforced confidence in test accuracy. (3) Interpretation of urine tenofovir results: TGW familiar with the interpretation of oral-fluid HIV self-tests knew that two lines on the test device signified positivity (presence of HIV). However, two lines on the urine test strip indicated a positive result for non-adherence (absence of tenofovir), causing confusion. Research nurses explained the difference in test interpretation to participants' satisfaction. (4) White coat dosing: Some TGW deliberately chose not to attend scheduled clinic appointments to avoid detecting their PrEP non-adherence during urine testing. They restarted PrEP before returning to clinic, a behaviour called "white coat dosing."

CONCLUSIONS

Incorporating POC urine testing into routine PrEP adherence counselling was acceptable and potentially beneficial for TGW but required attention to context. Additional research is needed to identify effective strategies for optimizing adherence monitoring and counselling for this population.

Point-of-care urine tenofovir monitoring of adherence to drive interventions for HIV treatment and prevention

INTRODUCTION

Although effective antiretroviral and pre-exposure prophylaxis/PrEP regimens are available globally, adherence challenges persist. Objective measures of adherence can both measure adherence accurately and can be used to drive interventions. The first point-of-care pharmacologic adherence measure, urine tenofovir testing using a lateral flow assay, is now available.

AREAS COVERED

This review examines the ability of pharmacologic metrics of adherence to predict HIV and PrEP clinical outcomes and the past use of pharmacologic metrics of adherence as tools to drive adherence interventions. The success of preliminary studies using point-of-care adherence metrics to guide interventions is then discussed.

EXPERT OPINION

Large randomized clinical trials are now needed to test the impact of point-of-care adherence interventions on HIV and PrEP clinical outcomes, given promising results of the pilot studies summarized here. Hybrid implementation-effectiveness studies will be needed to examine optimal approaches to incorporating point-of-care testing into routine clinical care delivery, including in guiding resistance testing, adherence counseling, and delivery of other evidence-based adherence interventions. Given the ability of point-of-care tenofovir testing to be implemented in settings where viral load testing is not available, and at more frequent intervals due to its low cost, urine-based tenofovir assays have the potential to be highly scalable in diverse clinical settings.

Comparing a point-of-care urine tenofovir lateral flow assay to self-reported adherence and their associations with viral load suppression among adults on antiretroviral therapy

BACKGROUND

Point-of-care (POC) lateral flow assays (LFA) to detect tenofovir (TFV) in urine have been developed to measure short-term ART adherence. Limited data exist from people living with HIV in routine care.

METHODS

Adults on TFV-containing regimens, having a routine viral load (VL) at an HIV clinic in Cape Town, South Africa were enrolled in a cross-sectional study. Patients recalled missed ART doses in the past three and 7 days and urine was tested using a POC TFV LFA. VL on the day was abstracted from medical records.

RESULTS

Among 314 participants, 293 (93%) had VL <1000 copies/mL, 20 (6%) had no TFV detected and 24 (8%) reported ≥1 missed dose in the past 3 days. Agreement between VL ≥1000 and undetectable TFV was higher compared to 3-day recall of ≥1 missed dose (Kappa 0.504 vs. 0.163, p = 0.015). The AUC to detect VL ≥1000 was 0.747 (95% CI 0.637-0.856) for undetectable TFV. This was statistically significantly better than for 7-day recall (0.571 95% CI 0.476-0.666, p = 0.040) but not for 3-day recall (0.587 95% CI 0.492-0.681, p = 0.071) of ≥1 missed dose.

CONCLUSION

In this largely virally suppressed cohort, TFV in urine had better agreement with VL than self-reported adherence and was a better predictor of viraemia on two of three self-report measures. Used in combination with VL, the POC urine TFV LFA could flag patients with viraemia in the presence of ART. Further research is needed to understand the potential application in different populations on ART, including pregnant women.

Adherence determination using urine-tenofovir point-of-care testing and pharmacy refill records: A cross-sectional study

Pharmacy refill records (PRR), are an accessible strategy for estimating adherence in low- and middle-income countries (LMICs). However, the low-cost urine-tenofovir point-of-care test opens up the possibility of an objective metric of adherence that is scalable to LMICs. This study compared adherence to tenofovir-based regimens using urine-tenofovir point-of-care (POC) test with pharmacy refill records in a Nigerian population of HIV-positive persons. This was a cross-sectional study among 94 HIV-positive adults, which was conducted from June to August 2021, in a large outpatient clinic in Lagos, Nigeria. Adherence to pharmacy appointments was automatically calculated using a computerized pharmacy appointment system (FileMaker Pro™). Urine drops on the urine-tenofovir POC test strip developed 2 lines for a negative test (tenofovir absent) and one line for a positive test. Fisher's exact test was used to examine the association between pharmacy refill record and urine-tenofovir point-of-care test. Logistic regression was performed to predict viral suppression (<1000 copies/mL, based on WHO recommendations) using both methods of adherence determination. A Receiver Operating Characteristic (ROC) curve of the association between specificity and sensitivity was generated to evaluate the predictive value of adherence determined using pharmacy-refill record and urine-tenofovir point-of-care test in forecasting viral suppression. The statistical significance level was set at 0.05. Fisher's exact test showed no statistically significant difference in adherence using urine-tenofovir point-of-care test or pharmacy refill record. The logistic regression model showed that an increase in pharmacy-refill record of ≥ 95% was associated with viral suppression (P = .019). From the ROC curve, the sensitivity was same at 95.5% for both methods, but the specificity of the urine-tenofovir point-of-care test was greater (96.6% vs 95.5%) than pharmacy refill record (P = .837). Urine-tenofovir point-of-care test provided equivalent adherence data to pharmacy refill data.

Adherence challenges with daily oral pre-exposure prophylaxis during pregnancy and the postpartum period in South African women: a cohort study

INTRODUCTION

Daily oral pre-exposure prophylaxis (PrEP) can reduce HIV acquisition. However, prevention effectiveness requires daily adherence prior to and during periods of sexual activity. Little is known about pharmacologic measures of PrEP adherence during pregnancy and postpartum and the factors related to optimal adherence during periods of sexual activity in this population.

METHODS

Between August 2019 and October 2021, we enrolled pregnant women without HIV at their first antenatal care visit followed-up through 12 months postpartum. Eligible women ≥16 years old received HIV prevention counselling and were offered oral PrEP (TDF-FTC). We quantified tenofovir-diphosphate (TFV-DP) in dried blood spots in women who reported taking PrEP in the past 30 days (at quarterly follow-up visits). We used regression models with generalized estimating equations to evaluate correlates of TFV-DP (any vs. none, and ≥2 vs. <2 doses/week), adjusting for maternal age and pregnancy status.

RESULTS AND DISCUSSION

In 382 women who started PrEP in pregnancy, returned for follow-up and reported PrEP use in the past 30 days, the median age was 27 years (interquartile range [IQR] = 23-32), and the median time on PrEP was 168 days (IQR = 84-252 days). Half of the samples had quantifiable TFV-DP at any time point (52%), declining from 67% of pregnant women 3 months post-initiation to 31% of postpartum women by 12 months. Overall, 72% had concentrations corresponding to <2 doses/week; 25% ≥2 doses/week; 3% 7 doses/week. Concentrations were lower in postpartum versus pregnancy (age-adjusted odds ratio [aOR] = 0.44; 95% confidence interval [CI] = 0.35-0.54). The correlation of self-reported adherence and TFV-DP ranged from -0.07 in pregnancy to 0.25 in postpartum women. Variables associated with having quantifiable TFV-DP included partner living with HIV/unknown serostatus (aOR = 1.50; 95% CI = 1.01-2.22), and reported frequency of sexual activity in the past month (aOR sex >5/month vs. no sex or <5 times/month = 2.11; 95% CI = 1.58-2.82) adjusting for age and pregnancy versus postpartum status. TFV-DP concentrations declined over follow-up time (aOR for 6 vs. 3 months = 0.49; 95% CI = 0.36-0.67).

CONCLUSIONS

Objectively measured adherence to PrEP was low overall and did not correlate with self-reported use. There is an urgent need for objective adherence measures to support clinical decision-making as well as adherence support interventions as part of PrEP services for pregnant and postpartum women at risk of HIV.

Urine tenofovir-monitoring predicts HIV viremia in patients treated with high genetic-barrier regimens

OBJECTIVE

Access to viral load measurements is constrained in resource-limited settings. A lateral flow urine tenofovir (TFV) rapid assay (UTRA) for patients whose regimens include TFV offers an affordable approach to frequent adherence monitoring.

DESIGN

We conducted a cross-sectional study of patients to assess the utility of UTRA to predict virologic failure, defined as a viral load greater than 400 copies/ml.

METHODS

We assessed urine TFV among 113 participants at increased risk of viral failure (who had previous viral failure on this regimen or had previously been ≥30 days out of care), comparing low genetic-barrier efavirenz (EFV) regimens (n = 60) to dolutegravir (DTG)-boosted or ritonavir-boosted protease inhibitor (PI/r)-based high genetic-barrier regimens (n = 53). Dried blood spots (DBS) for TFV-diphosphate and plasma for TFV concentrations were collected, with drug resistance assessed if viral failure present.

RESULTS

Among 113 participants, 17 of 53 received DTG or PI/r had viral failure at the cross-sectional visit, with 11 (64.7%) demonstrating an undetectable urine TFV; the negative-predictive value (NPV) of undetectable UTRA for viral failure was 85% (34/40); none of the 16 sequenced had dual class drug resistance. In those treated with EFV regimens the sensitivity was lower, as only 1 (4.8%) of 21 with viral failure had an undetectable UTRA (P < 0.001).

CONCLUSIONS

Urine tenofovir-testing had a high negative-predictive value for viral failure in patients treated with DTG or ritonavir-boosted protease inhibitor regimens, where viral failure was largely explained by poor drug adherence. Frequent monitoring with inexpensive lateral flow urine TFV testing should be investigated prospectively in between viral load visits to improve viral load suppression on DTG-based first-line therapy in resource-limited settings.