Abstract
Among South African women using oral HIV preexposure prophylaxis, we compared a urine tenofovir point-of-care test with dried blood spot tenofovir diphosphate concentrations for recent vs longer-term adherence and assessed acceptability. The test demonstrated 76% accuracy, 100% sensitivity, and 69% specificity for high adherence (tenofovir diphosphate ≥700 fmol/punch) and was highly acceptable.
Clinical Trials Registration: NCT04038060.
Keywords: adherence, women, HIV, point of care, preexposure prophylaxis
INTRODUCTION
In 2024, three-quarters of new HIV infections in eastern and southern Africa occurred in adolescent girls and women (AGYW) [1]. Daily oral tenofovir disoproxil fumarate/emtricitabine (TDF/FTC) for HIV preexposure prophylaxis (PrEP) is highly effective when ≥4 doses are taken per week [2]. However, suboptimal PrEP adherence and discontinuation remain common among AGYW [3].
Counseling with objective adherence markers could improve PrEP adherence and continuation. Counseling with plasma tenofovir (TFV) concentrations significantly improved oral PrEP adherence among men in the PATH-PrEP study [4]. However, counseling with tenofovir diphosphate (TFV-DP) concentration in dried blood spots (DBS) did not improve oral PrEP adherence in AGYW in the HPTN 082 trial [5]. DBS testing requires specialized laboratories and measures average adherence over the prior 4 to 8 weeks with a delayed turnaround time; therefore, adherence counseling with DBS is limited by PrEP users’ need to recall pill taking from the prior 3 months [5–7]. Urine TFV testing, like plasma metrics, reflects recent dosing and is moderately correlated with DBS TFV-DP concentrations [8].
A urine TFV point-of-care test (POCT) provides same-day assessment of TDF/FTC use (within the previous 4–7 days), is highly sensitive (99%) and specific (97%), and is estimated to cost US $2 to $5 once commercially available [9–10]. POCT-based counseling improved antiretroviral therapy adherence and viral load suppression among people with HIV in Namibia and supported adherence among oral PrEP users in Kenya [11, 12]. We assessed the performance and acceptability of the urine TFV POCT, as compared with DBS, for oral PrEP adherence counseling in young South African women.
METHODS
Study Design and Participants
PrEP SMART was a sequential multiple-assignment randomized trial evaluating adaptive PrEP adherence strategies in Johannesburg, South Africa, from 2019 to 2021 and has been published elsewhere [13, 14]. Briefly, sexually active women aged 18 to 25 years who provided written informed consent and newly initiated PrEP were randomized 1:1 to receive 2-way SMS or WhatsApp peer support [15, 16]. Participants with suboptimal adherence at month 2 were randomized a second time to receive monthly issue-focused counseling or quarterly adherence counseling based on TFV-DP concentrations in DBS [13, 14].
Ethics Statement
The study was approved by the research ethics committee of the University of the Witwatersrand and the institutional review board of the University of Washington.
Study Procedures
All participants attended quarterly follow-up visits from month 3 for up to 12 months for HIV testing and PrEP refills. Follow-up was reduced from 12 to 9 months due to the COVID-19 pandemic. Because POCT kits became available midtrial, this analysis includes only a subset that consented to POCT-based counseling at the exit visit. Participants provided urine samples for urine TFV POCT, by on-site medical technologists, with results available in 3 to 5 minutes for study clinicians to provide supportive counseling [5]. Participants with urine TFV detected were affirmed for recent PrEP adherence and encouraged to maintain daily pill taking (Supplementary Figure 1). Reasons for urine TFV not detected were explored and counseling provided to encourage daily pill taking. Participants completed a brief 8-item computer-assisted self-interview using a 4-point Likert scale (strongly disagree to strongly agree) to assess acceptability of POCT-based counseling. Those randomized to DBS-based counseling completed additional questions to assess preferences for counseling based on urine or blood testing. All participants provided a blood sample for measurement of intracellular TFV-DP concentrations in DBS at the University of Cape Town pharmacology laboratory [17].
Statistical Analysis
TFV-DP concentrations were dichotomized to ≥700 fmol/punch for high adherence and <700 fmol/punch for suboptimal adherence. This threshold of 700 fmol/punch, indicating a mean ≥4 doses taken per week, has been established to provide HIV protection in cisgender women [2]. We assessed the sensitivity, specificity, and predictive values of the urine TFV POCT by comparing results with the DBS high-adherence threshold. For further assessment of POCT results, TFV-DP concentrations on DBS were categorized into 350 to 699 fmol/punch (2 or 3 doses/wk), lower limit of quantification to 349 fmol/punch (<2 doses/wk), and below the limit of quantification. Acceptability was assessed by median response scores and by dichotomized responses (agree vs disagree) to provide a simple measure of overall acceptability. Rank sum and χ2 tests were used to compare median scores and response proportions by POCT result. The VOICE risk score was calculated by demographic and behavioral data to evaluate HIV risk [18].
RESULTS
Participant Characteristics
Of 163 participants who completed POCT at the month 9 (n = 116) or month 12 (n = 47) exit visits, 115 (71%) had DBS results at month 9 for comparison, and 36 (22%) received quarterly adherence counseling based on DBS TFV-DP concentrations.
At enrollment, the median age was 21 years (IQR, 20–23), and 99% (162/163) had some secondary education or higher (Table 1). Participants reported a median 2 partners (IQR, 1–2) in the past 3 months, 21% (32/163) reported transactional sex in the past 3 months, and the overall sample had a median VOICE risk score of 6 (IQR, 6–7). Baseline characteristics of participants who received POCT-based counseling did not differ significantly from those that did not.
Table 1.
Participant Characteristics at Baseline and Acceptability of Urine Tenofovir POCT-Based Adherence Counseling at Exit Visit
| Urine TFV, No. (%) or Median (IQR) | |||
|---|---|---|---|
| Detected | Not Detected | P Value | |
| Baseline participant characteristics (N = 163) | 91 | 72 | |
| Age, y | 21 (20–23) | 22 (20–23) | |
| Highest level of education achieved | |||
| No schooling | 1 (1) | 0 (0) | |
| Primary school | 0 (0) | 0 (0) | |
| Some secondary school/secondary school | 56 (62) | 32 (44) | |
| Above secondary school | 34 (37) | 40 (56) | |
| Lives with | |||
| No one | 3 (3) | 6 (8) | |
| Partner | 7 (8) | 3 (4) | |
| Family | 79 (87) | 53 (74) | |
| Other | 5 | 11 | |
| Occupation | |||
| Student | 34 (37) | 38 (53) | |
| Employment with a steady salary/formal sector | 6 (7) | 8 (11) | |
| Employment without a steady salary/informal sector | 4 (4) | 4 (6) | |
| Unemployed | 47 (52) | 22 (30) | |
| In past 3 mo | |||
| No. of partners | 2.0 (1.0–2.0) | 2.0 (1.0–2.0) | |
| Transactional sex | 14 (20) | 18 (23) | |
| AUDIT-C score ≥3a | 47 (65) | 52 (57) | |
| Contraceptive use | |||
| Oral | 5 (7) | 7 (8) | |
| Injectable | 19 (26) | 26 (29) | |
| Implant | 5 (7) | 8 (9) | |
| Intrauterine device | 1 (1) | 0 (0) | |
| Condoms | 12 (17) | 15 (16) | |
| None | 30 (42) | 35 (38) | |
| Modified VOICE risk scoreb | 7 (6–8) | 6 (5–7) | |
| Ever taken PEP | 3 (4) | 0 (0) | |
| Symptoms of an STI at enrollment | 2 (3) | 1 (1) | |
| STI diagnosed at enrollment | 23 (25) | 21 (29) | |
| Chlamydia trachomatis | 19 (26) | 17 (19) | |
| Neisseria gonorrhea | 1 (1) | 2 (2) | |
| Trichomonas vaginalis | 2 (3) | 4 (4) | |
| Positive syphilis serologyc | 2 (2) | 2 (3) | |
| Acceptability of POCT-based adherence counseling among all participants (n = 157)d,e | |||
| Understood their POCT results | 69 (99), 3 | 81 (94), 2 | <.01 |
| Expected their POCT results | 69 (100), 3 | 77 (90), 2 | <.01 |
| POCT-based counseling helped to communicate with health care providers | 69 (99), 3 | 80 (92), 2 | .01 |
| Felt emotionally supported during POCT-based counseling | 68 (97), 3 | 78 (91), 2 | <.01 |
| Liked receiving counseling on how much PrEP was in their body based on the POCT | 67 (97), 3 | 78 (91), 2 | .01 |
| Found POCT-based counseling helpful for HIV prevention | 68 (99), 3 | 78 (91), 2 | .02 |
| POCT-based counseling on recent PrEP use would motivate taking PrEP more often | 69 (99), 3 | 83 (97), 2 | .10 |
| Would choose to have POCT-based counseling in the future | 68 (97), 3 | 85 (99), 2.5 | .14 |
| Acceptability of POCT-based adherence counseling among participants with DBS (n = 33) | |||
| Method that was easiest to understand | .39 | ||
| Urine | 2 (40) | 14 (50) | |
| Blood | 0 (0) | 5 (18) | |
| Both or about equal | 3 (60) | 9 (32) | |
| Method that was consistent with actual PrEP use | .91 | ||
| Urine | 2 (40) | 11 (39) | |
| Blood | 1 (20) | 8 (29) | |
| Both or about equal | 2 (40) | 9 (32) | |
| More challenging to remember PrEP use based on blood test vs POCTf | 2 (40) | 16/26 (62) | .37 |
| Method that motivated consistent PrEP use | .82 | ||
| Urine | 2 (40) | 9 (32) | |
| Blood | 1 (20) | 8 (29) | |
| Neither | 0 (0) | 3 (11) | |
| Both or about equal | 2 (40) | 8 (29) | |
| Method that was liked bestg | .37 | ||
| Urine | 2 (40) | 13/27 (48) | |
| Blood | 0 (0) | 6/27 (22) | |
| Both or about equal | 3 (60) | 8/27 (30) | |
| Method that would be preferred in the future | .34 | ||
| Urine | 1 (20) | 10 (36) | |
| Blood | 0 (0) | 5 (18) | |
| Both or about equal | 4 (80) | 13 (46) | |
Abbreviations: PEP, postexposure prophylaxis; POCT, point-of-care test; PrEP, preexposure prophylaxis, STI, sexually transmitted infection; TFV, tenofovir.
aAUDIT-C score is based on responses to the first 3 items of the AUDIT-C module. Possible scores range from 0 to 12, with a greater score indicating endorsement of more alcohol use. A score ≥3 is considered positive.
bModified VOICE risk score includes age <25 years; not married or living with partner; alcohol use in past 3 months; partner does not provide financial/material support; and partner has had other sex partners.
cPositive syphilis serology is defined as positive if nontreponemal and treponemal tests were both reactive.
dResponses to acceptability items: 0 = strongly disagree, 1 = disagree, 2 = agree, 3 = strongly disagree.
e P value of median scores, which are provided with No. (%).
fTwo missing among those with urine TFV not detected, as 2 participants did not respond to this item.
gOne missing among those with urine TFV not detected, as 1 participant did not respond to this item.
Performance of the Urine TFV POCT
Overall, 44% (72/163) of participants had urine TFV detected at study exit. Among those with POCT and DBS at 9 months, 23% (26/115) had TFV-DP concentrations ≥700 fmol/punch (Figure 1). Among participants with DBS and urine TFV detected, 48% (26/54) had TFV-DP concentrations ≥700 fmol/punch. For participants with DBS and urine TFV not detected (n = 61), 100% had TFV-DP concentrations <700 fmol/punch. Overall, the POCT had 76% accuracy, 100% sensitivity (95% CI, 87%–100%), 69% specificity (95% CI, 58%–78%), 48% positive predictive value (95% CI, 34%–62%), and 100% negative predictive value (95% CI, 94%–100%) for identifying high adherence (DBS TFV-DP concentrations ≥700 fmol/punch).
Figure 1.
Participant urine tenofovir test results categorized by DBS TFV-DP concentrations (n = 115). BLQ, below level quantifiable; DBS, dried blood spots; LLQ, lower limit quantifiable; TFV-DP, tenofovir-diphosphate.
Acceptability of POCT and Same-Day Counseling
Most participants (>90%) found POCT-based counseling understandable, supportive, and helpful for HIV prevention (Table 1). Participants with urine TFV detected generally had significantly higher median acceptability scores as compared with those with urine TFV not detected (3 vs 2, P < .05). Among the subset of participants who received quarterly DBS-based counseling, 47% (15/32) liked urine POCT-based counseling, 19% (6/32) liked DBS-based counseling, and 34% (11/32) liked both. More than half (58%, 18/31) confirmed that it was more challenging to recall PrEP use in the 4 to 8 weeks prior to the visit for counseling purposes, as compared with the previous several days. Among participants with urine TFV not detected, 36% (n = 10) preferred urine testing as opposed to 18% (n = 5) who preferred blood testing for future use, although the small number with detectable TFV limits direct comparison.
DISCUSSION
In this population of AGYW taking oral PrEP, less than half had urine TFV detected at study exit. The POCT was highly acceptable to participants and correctly classified most of them, although it overestimated adherence for some with TFV detected when compared with TFV-DP on DBS. Reassuringly, all of those with urine TFV not detected had TFV-DP concentrations <700 fmol/punch, indicating poor to moderate adherence in the previous 4 to 8 weeks, and would have received counseling to manage barriers for PrEP use. However, the lower specificity and positive predictive value of the POCT for high adherence mean that one-quarter of participants with poor/fair adherence were misclassified as being adherent. White coat dosing may have created missed opportunities for identifying adherence issues with AGYW who may have been falsely reassured regarding HIV protection despite less-than-optimal dosing over a longer period.
AGYW in this study found the POCT and same-day counseling acceptable, consistent with other studies in Africa [12, 19]. AGYW with urine TFV detected had higher acceptability scores than those with TFV not detected. This confirms qualitative findings in Kenya, which suggested that individuals with positive results would be more likely to prefer POCT-based counseling [19]. We observed that AGYW with urine TFV not detected had greater preference for urine testing over DBS than those with TFV detected, suggesting that AGYW with adherence challenges may have appreciated the direct feedback and supportive counseling. Other studies have reported higher acceptability of urine testing as compared with blood testing for PrEP monitoring [19, 20]. These findings highlight the importance for PrEP providers to encourage consistent pill taking and provide supportive counseling, irrespective of the result.
Several limitations in this analysis may limit generalizability, including data collection at study exit and the number of participants assessed. Notably there were no meaningful differences in baseline characteristics between those who did and did not have a POCT. We compared the POCT against a DBS TFV-DP cutoff corresponding to a mean ≥4 doses per week. This threshold was selected to distinguish those who had high adherence for HIV protection from those needing additional adherence support. Although this may underestimate the test's true performance, it offers a programmatic comparison. All participants received TDF/FTC; however, the assay also accurately assesses adherence to tenofovir alafenamide/emtricitabine PrEP [21].
CONCLUSIONS
Same-day adherence counseling with a POCT was highly acceptable and correctly classified most AGYW to receive appropriate counseling for oral PrEP adherence. Targeted testing strategies may provide early assessment for individuals needing additional support. Additional randomized studies are needed to assess whether same-day counseling based on urine TFV results leads to higher PrEP adherence and greater HIV prevention benefits.
Supplementary Material
Notes
Acknowledgments. We thank the PrEP SMART study team, the participants, and their communities.
Author contributions. C. C., S. D.-M., J. V., N. P., A. M., and S. H. designed the research study. N. P., N. H. N., J. V., and S. D.-M. conducted the research. C. G., J. V., and N. P. analyzed the data. M. G. provided essential tools. N. P. drafted the initial manuscript. All authors have read and approved the final manuscript.
Data availability. Data may be made available from the corresponding author upon reasonable request.
Financial support. This work was supported by funding provided from the National Institute of Mental Health and National Institute of Health (grants R01MH114544 and 2R01AI143340 to C. C.).
Contributor Information
Nicole Poovan, Wits RHI, University of the Witwatersrand, Johannesburg, South Africa.
Jennifer Velloza, Department of Global Health, University of Washington, Seattle, Washington, USA.
Nontokozo H Ndlovu, Wits RHI, University of the Witwatersrand, Johannesburg, South Africa.
Allison Meisner, Vaccine and Infectious Diseases Division, Fred Hutchinson Cancer Center, Seattle, Washington, USA.
Cole Grabow, Department of Global Health, University of Washington, Seattle, Washington, USA.
Monica Gandhi, Division of HIV, Infectious Diseases, and Global Medicine, University of California San Francisco, San Francisco, California, USA.
Deborah Donnell, Vaccine and Infectious Diseases Division, Fred Hutchinson Cancer Center, Seattle, Washington, USA.
Sybil Hosek, Department of Medicine, University of Illinois Chicago, Chicago, Illinois, USA.
Connie Celum, Wits RHI, University of the Witwatersrand, Johannesburg, South Africa; Department of Global Health, University of Washington, Seattle, Washington, USA; Department of Medicine, University of Washington, Seattle, Washington, USA.
Sinead Delany-Moretlwe, Wits RHI, University of the Witwatersrand, Johannesburg, South Africa.
Supplementary Data
Supplementary materials are available at Open Forum Infectious Diseases online. Consisting of data provided by the authors to benefit the reader, the posted materials are not copyedited and are the sole responsibility of the authors, so questions or comments should be addressed to the corresponding author.
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