Optimizing CAB-LA as PrEP for Women Who Inject Drugs

This open-label community demonstration project draws from parent study TIARAS (NCT05192434), a multi-component behavioral intervention designed to reduce HIV acquisition risk among women who inject drugs (WWID). Participants are prescribed PrEP prior to enrollment based on consultation with their medical provider. They then simultaneously enroll in TIARAS and this observational study. Over six months, we will use data extracted from participant's electronic medical records to (1) describe CAB-LA and daily oral PrEP uptake among WWID and (2) assess for differences in adherence and persistence among WWID prescribed CAB-LA versus daily oral PrEP. All quantitative analyses will control for random group assignment in the TIARAS trial (NCT05192434). To understand uptake (primary outcome), we will purposively sample 20 WWID who were prescribed CAB and 20 prescribed daily oral PrEP. Participants will complete a semi-structured interview designed to explore their decision to initiate PrEP and the product-related attributes that influenced their decision, accounting for previous PrEP experience or use of long-acting injectable medications (e.g., birth control or MOUD), and examining how structural factors, like homelessness or medical mistrust influence decision-making. To understand persistence and adherence, at endline (six-months) we will purposively recruit 10 women who initiated CAB-LA who remained actively engaged in care and 10 who did not. We will also purposively recruit 10 women who initiated daily oral PrEP who remained actively engaged in care and 10 who did not. All participants will complete a semi-structured interview that explores facilitators and barriers to adherence and persistence (secondary outcomes). We will focus on strategies to increase engagement in care. Because previous research highlights the important influence of seasons of risk on PrEP outcomes (i.e., women are less interested in PrEP during periods of low perceived HIV risk such as during drug abstinence), we will examine how individual and structural factors influence PrEP persistence. Finally, should we find that \>10% of the sample switches or discontinues a PrEP formulation over time, we will recruit a subset (n=15) to understand their decision-making process about switching.