NOVEL TESTING STRATEGIES TO SUPPORT HIV TREATMENT AND PREVENTION: ACCEPTABILITY, PREFERENCES, AND IMPACT ON ENGAGEMENT IN CARE AND SEXUAL BEHAVIORS

Thesis (Ph.D.)--University of Washington, 2023The primary goal of this dissertation project was to advance our understanding of the impact of novel testing strategies to support HIV treatment and prevention. Despite significant advancements in antiretroviral therapy (ART) and pre-exposure prophylaxis (PrEP), rates of suboptimal medication adherence and disengagement from care, particularly in the first year of care, remain extraordinarily high. Novel strategies are urgently needed to improve ART and PrEP adherence and retention in care, in order to reduce HIV transmission and mortality. Point-of-care (POC) urine tenofovir testing is a newly developed tool that can provide real-time drug-level feedback for people living with HIV (PLWH) receiving ART, which could also prompt timely interventions for those experiencing adherence challenges. However, little is known about how PLWH and healthcare providers will perceive a POC urine tenofovir testing intervention and how it will impact behaviors. In Chapter 1, we conducted a qualitative study to assess the acceptability of monthly POC urine tenofovir testing in the first five months of care for PLWH and healthcare providers in South Africa. We also explored participants’ perspectives on differentiated strategies for the implementation of POC urine tenofovir testing that may be useful and appropriate for PLWH. Overall, PLWH and healthcare providers found the monthly POC urine tenofovir testing intervention to be highly acceptable, generally preferred over self-reported adherence, and motivational for improving ART adherence. Other implementation strategies in which participants believed POC urine tenofovir testing could be provided, included: testing at community-based sites where ART is refilled, random testing at clinic visits, and testing delivered by counselors or other healthcare workers. Monthly POC urine tenofovir testing in the first five months of HIV care is an acceptable and potentially effective strategy for improving ART adherence. Novel strategies for HIV testing for people at risk of acquiring HIV may also be beneficial for improving outcomes, but it is important to understand how clients’ testing preferences impact the intended outcomes. For HIV prevention, regular HIV testing is a required core component of PrEP delivery necessary to ensure a prompt transition to ART and reduce the risk of drug resistance. HIV self-testing (HIVST) may be an effective tool for supporting efficient PrEP delivery, allowing for non-clinic-based HIV testing when appropriate. A differentiated service delivery (DSD) model for PrEP that includes semiannual clinic visits, six-month PrEP dispensing, and HIVST between clinic visits resulted in non-inferior outcomes for PrEP continuation. In practice, though, PrEP clients’ unique needs and preferences should be considered when choosing an appropriate and effective delivery model. In Chapter 2, we used data from the JiPime-JiPrEP trial (NCT03593629) to determine if receiving a preferred HIV testing modality to support PrEP delivery is associated with better PrEP continuation outcomes compared to receiving a non-preferred modality. Findings from Chapter 2 indicated no significant differences in PrEP continuation behaviors between participants receiving their preferred HIV testing modality and those receiving their non-preferred modality. This DSD model of semiannual clinic visits with six-month PrEP dispensing and HIVST reduced the frequency of clinic visits without compromising PrEP continuation outcomes, but its effect on other behaviors associated with HIV risk acquisition, such as sexual behaviors, is not well known. In Chapter 3, we evaluated the effect of this DSD model of PrEP delivery supported with interim HIVST—which reduces the frequency of sexual and reproductive health and associated counseling services—on participants’ sexual behaviors. We found no significant differences in sexual behaviors between participants receiving a DSD model of PrEP that included semiannual clinic visits and HIVST and participants receiving standard-of-care. DSD models of PrEP delivery and HIV testing, including those that incorporate HIVST, that are person-centered and tailored to clients’ unique needs and preferences may result in comparable outcomes to standard-of-care PrEP delivery models. Collectively, these findings provide some of the first insights on the acceptability of monthly POC urine tenofovir testing for PLWH in South Africa, PrEP continuation behaviors for clients receiving a DSD model supported with their preferred HIV testing modality, and sexual behaviors for PrEP clients receiving a DSD PrEP delivery model supported with HIVST versus standard-of-care PrEP delivery. Evidence gleaned from this dissertation will be valuable for guiding development of person-centered models of care and testing strategies to support HIV treatment and prevention