Abstract
BACKGROUND: Pre-exposure prophylaxis (PrEP) holds promise for decreasing new HIV infections among people who inject drugs (PWID), yet daily oral PrEP use is low, and PrEP modality and delivery strategy preferences in this population remain understudied. METHODS: From May 2022-June 2023, we conducted a discrete choice experiment (DCE) with PWID in San Diego, California. Participants viewed 18 PrEP program scenarios in sets of three and chose their preferred scenario within each set. Scenarios consisted of various combinations of five characteristics: PrEP modality (injectable, implantable, oral), frequency of use (annual, bi-monthly, daily), service location (community-based organization, clinic, telemedicine), prescription access location (on-site, street outreach, mail), and adherence supports (social support, outreach worker, phone/text reminder). Multinomial logit regression estimated probabilities of choosing PrEP program scenarios as a function of the five characteristics to estimate part-worth utility scores (PWUS; reflecting relative preferences for specific characteristic values) and relative importance scores (RIS; reflecting the relative influence of each characteristic on program choice). We also explored differences by hypothesized modifiers of preferences (i.e., sex assigned at birth, housing status, injection frequency, prior PrEP awareness). RESULTS: Among 262 participants, mean age was 43.1 years, and most reported male sex assigned at birth (69.5%), identified as non-Hispanic (60.3%), and were previously unaware of PrEP (75.2%). Frequency of use (RIS: 51.5) and PrEP modality (RIS: 35.3) had the greatest influence on PrEP program choice. Within these characteristics, participants had relative preferences for annual use (PWUS: 0.83) and oral PrEP (PWUS: 0.57), and relative aversions to daily use (PWUS: -0.76) and implantable PrEP (PWUS: -0.53). Generally, participants did not indicate preferences for specific service or prescription access locations, or adherence supports; however, among those with prior PrEP awareness, prescription access location and adherence supports had a slightly greater influence on PrEP program choices. CONCLUSION: Our study considered diverse PrEP scenarios and highlighted potential preferences for long-acting oral modalities. Although not currently available, renewed investment in long-acting oral PrEP formulations may facilitate PrEP care engagement among PWID. Additional delivery and implementation strategy research is needed to support PrEP uptake and persistence in this population.