Although initiation rates of HIV pre-exposure prophylaxis (PrEP) increased and HIV infection incidence decreased among a cohort of young women in South Africa and Zimbabwe, enhanced adherence support using drug feedback from intracellular tenofovir-diphosphate (TFV-DP) measurements obtained from dried blood spots was not associated with increased HIV PrEP adherence, according to study results published in PLOS Medicine.

In this phase 4, prospective, multisite trial (HIV Prevention Trials Network 082; ClinicalTrials.gov identifier: NCT02732730), researchers assessed HIV PrEP uptake and adherence among women without HIV infection (median age, 21 years) in South Africa and Zimbabwe. Participants were randomly assigned in a 1:1 fashion to receive oral HIV PrEP with either standard adherence support or enhanced adherence support. Standard adherence support included a package with 2-way texting, brief counseling, and optional peer adherence support clubs; and, enhanced adherence support included standard adherence support plus counseling based on feedback from intracellular TFV-DP measurements obtained from dried blood spots.

The primary outcome for the enhanced adherence support group was a TFV-DP concentration of 700 fmol/punch or more at 6 months. Participants were followed for 12 months and could discontinue PrEP any time during the study period.


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Of the 451 participants enrolled, 95% initiated PrEP: 212 were assigned to the standard adherence support group and 215 were assigned to the enhanced adherence support group. In regard to the prevalence of seropositive sexually transmitted infections among participants in both groups, 29% had Chlamydia trachomatis, 8% had Neisseria gonorrhoeae, 7% had Trichomonas vaginalis, and less than 1% had syphilis. Of note, 82% of participants planned to disclose their use of PrEP, and most reported positive attitudes about PrEP.

At 12 months, 55% of participants continued PrEP use without interruption, with minimal differences noted between the 2 groups (P =.27). Among 110 participants, there were 40 temporary and 74 permanent discontinuations of PrEP.

At 6 months, the intention-to-treat analysis showed that PrEP adherence did not differ between the standard vs enhanced support group (21.7% [40/184] vs 20.1% [36/179]; adjusted odds ratio [aOR], 0.92; 95% CI, 0.55-1.34; P =.76). Findings remained similar in the per-protocol analysis, which excluded participants who discontinued PrEP due to pregnancy or decreased creatinine clearance (>10%), as well as those in the enhanced support group who did not receive adequate adherence feedback. PrEP adherence among participants in the standard support group was 22.4% (40/178) vs 15.2% (17/112) among those in the enhanced support group (aOR, 0.64; 95% CI, 0.34-1.21; P =.17).

Of note, 4 participants in the standard adherence support group developed HIV infection.

The limitations of the study included limited awareness about HIV PrEP among the participants. In addition, there was limited “power to detect a modest effect of retrospective drug level feedback on subsequent PrEP adherence,” the researchers noted.

“Effective and scalable strategies are needed to increase adherence and persistence to daily PrEP among young African women as well as additional options, particularly longer-acting PrEP formulations, for young women for whom consistent [contraception] is not feasible,” the researchers concluded.

Disclosure: Some study author(s) declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of disclosures.

Reference

Celum C, Hosek S, Tsholwana M, et al. PrEP uptake, persistence, adherence, and effect of retrospective drug level feedback on PrEP adherence among young women in southern Africa: results from HPTN 082, a randomized controlled trial. PLoS Med. 2021;18(6):e1003670. doi:10.1371/journal.pmed.1003670