Preferences for long-acting Pre-Exposure Prophylaxis (PrEP) for HIV prevention among South African youth: results of a discrete choice experiment

Introduction: Existing biomedical HIV prevention options, though highly effective, present substantial adherence challenges. End-user input on early-stage design of new HIV prevention approaches is critical to yielding products that achieve high uptake and adherence. The iPrevent Study examined youths' preferences for key attributes of long-acting Pre-Exposure Prophylaxis (PrEP), with a focus on characteristics pertinent to product delivery alongside key modifiable product attributes.

Methods: A discrete choice experiment was conducted with female and male youth aged 18 to 24 in two high-density communities in Cape Town, South Africa during the period July 2017 to January 2019. Sexually active, PrEP-naïve youth were recruited using population-based sampling; targeted sampling was used to enrol men who have sex with men (MSM). In a series of nine questions, participants were asked to choose between two hypothetical products composed of five attributes (form, dosing frequency, access, pain, insertion site). We used a random-parameters logit model to estimate preference weights and trade-offs among product alternatives. We examined differences across three subgroups: females, men who have sex with only women (MSW) and MSM.

Results: A total of 807 participants (401 female) were enrolled with a median age of 21 years. Males included 190 MSM. Most youth had tested for HIV (95%) and reported being HIV-negative (91%). Across all groups, duration of effectiveness was the most important attribute, with strong preference for less frequent dosing. Injections were favoured over implants, though these preferences were strongest for females and MSM. Females preferred a product offered at a health clinic and disliked pharmacy access; all groups preferred the arm as the insertion site. Youth were willing to trade their preferred product form for longer duration.

Conclusions: Youth indicated strong preferences for longer duration products. Each attribute nonetheless influenced preferences, offering insight into trade-offs that inform long-acting PrEP development.