The objective of this R34 application is to prepare for testing innovative user-centered ways to promote PrEP adherence at scale. Our central hypothesis is that adherence to PrEP can be improved among MSW if PrEP is provided for free along with highly-tailored conditional economic incentives (CEI). The specific aims are: Aim 1: To refine the design of PrEP adherence intervention with user-centered conditional economic incentives to maximize sustained adherence behaviors through a user-responsive computerized survey (n=200). We incorporate quantitatively identified preferences for CEIs through a user- responsive computerized survey. We use conjoint analysis to understand preferences for CEI intervention components and how CEIs should be integrated into an optimal combination package to be tested in Aim 2. Aim 2: Measure the extent to which a user-centered CEI intervention can help MSW increase their adherence to free PrEP in a randomized controlled pilot (n=100). Among MSW who accept to take free PrEP, and return at month 1 for a second pill bottle, we will randomize n=100 MSW to either: standard of care (SoC: information, prescription, free PrEP) or CEI (SoC + incentives contingent on sufficiently-high adherence to PrEP). We will assess the primary outcome (biomarker of adherence using scalp hair analysis) at months 3 and 6, as well as secondary outcomes: clinic attendance/retention, medication possession ratio, self-reported PrEP use, and sexual behavioral disinhibition (number of partners, condom use, incident STI). Aim 3: Estimate the preliminary cost-effectiveness of incentives for PrEP adherence to maximize future policy and practice relevance of this promising intervention strategy. Our working hypothesis is that conditional economic incentives for PrEP adherence will be cost-effective in terms of cost per fully- adherent month on PrEP, cost per HIV infection averted, and cost per disability-adjusted life year saved when compared to controls not receiving the conditional incentives. The expected outcome of this R34 is a demonstration that is feasible to implement user-centered CEIs in this context, as well as preliminary efficacy and cost-effectiveness data. The project will have positive impact because it is a critical step toward scaled-up implementation of PrEP in this highly-at-risk population of MSWs in Mexico, with implications for other concentrated epidemics among MSW worldwide.

Inclusion Criteria:

• Male at birth and self-identifies as male at the time of enrollment
• At least 18 years of age
• Has tested negative for HIV in the past month
• Demonstrates high risk of HIV acquisition defined as having had sex with penetration (oral or anal) with at least 8 male partners in past six months
• Has exchanged or accepted money, drugs or gifts in exchange for sex on at least 8 occasions in the past month
• Willing and capable of providing blood and scalp hair samples for assessments
• Willing and able to provide written informed consent
• Have successfully initiated PrEP and are returning for their second bottle of PrEP pills
• Able to provide a home address or personal telephone number, or able to provide two personal contacts who will be able to know the patient's whereabouts during the study period

Exclusion Criteria

• Under 18 years of age
• Unable to give informed consent due to severe mental or physical illness/substance intoxication at baseline visit
• Presents with severe adverse reactions to PrEP
• The subject will be excluded from the study at his own request for any reason since participation is voluntary

Male

Materials generated under this project will be disseminated according to University and NIH policies regarding data sharing. Aggregate-level data collected in this collaboration will ultimately be available for public use. Opportunities for secondary analyses will be available following completion of the three-year project and publication of the main study findings. These findings will be available to the public through scientific meetings and peer-reviewed journals, as well as through a structured policy dissemination process.