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 MSWs who accept to take free PrEP, and return for a second pill bottle, we will randomize n=100 MSWs 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.

Study Design

Procedures:

A pilot randomized controlled trial of 110 male sex workers (MSWs) will be conducted to measure the effect of conditional economic incentives (CEI) on improving adherence to pre-exposure prophylaxis (PrEP) among MSWs. The randomized trial will consist of two arms, a control arm and an intervention arm. Participants in both arms will receive standard prophylaxis, which includes free PrEP. Participants in the intervention arm will additionally receive CEI to promote adherence to PrEP. The main outcome measure is the adherence biomarker (measured by analysis of antiretroviral accumulation in the hair at 3 and 6 months). Other outcome measures that will be analyzed include clinic attendance/retention, proportion of medications possessed, self-reported PrEP use and risk behaviors (number of sexual partners, condom use, STI incidence.

Inclusion Criteria

• Willing to provide a residential address or personal phone number, or two personal contacts who will be able to locate the participant during the course of the study;
• No previous history of kidney disease.
• Self-identify as male;
• Male sex at birth;
• Have had sex with penetration (oral or anal) in the past 6 months with at least 8 men;
• Have exchanged money, drugs, alcohol or gifts for sex in the past month at least 8 times;
• HIV screening test with a negative result in the past month;
• Successfully started PrEP and is returning for their second bottle of PrEP pills;
• Willing and able to provide informed consent;
• Willing to provide a residential address or personal phone number, or two personal contacts who will be able to locate the participant during the course of the study.
• Able and willing to provide written informed consent;
• > 18 years of age;
• Native Spanish-language speaker or fluent in Spanish;
• HIV-1 seronegative, defined as: Rapid HIV antibody test with negative result in the recruitment visit
• Evidence of high risk for acquiring HIV-1 infection, which includes any of the following:
• Anal sex without a condom with male or transgender sexual partners in the past 6 months; or
• Anal sex with at least an HIV positive partner in the past 6 months; or
• Report of diagnosis of gonorrhea or rectal/urethral chlamydia or syphilis in the 6 months prior to recruitment, or diagnosed with the aforementioned during the screening phase; or
• Report of sex in exchange for money, gifts, lodging, or drugs in the previous 6 months.
• Has had a HIV positive partner with a detectable or unknown viral load in the past 3 months.

Study visits occurred at baseline (time=1), month 3 (time=2), and month 6 (time=3). At each visit, all participants received a free 3-month supply of PrEP (i.e., 90 pills) in the form of a once-daily tablet containing 200 mg of emtricitabine (FTC) and 300 mg of tenofovir disoproxil fumarate (TDF), an HIV test, counseling to reduce risks, condoms, management for STIs as needed, and transport reimbursement of 100 Mexican pesos (~$5 USD).

At each of the two follow-up visits (month 3 and month 6) MSWs in the CEI intervention arm were informed they would receive incentives (in addition to transport reimbursement) at their next appointment, and that the incentive amount would be based on their PrEP medication adherence as measured via FTC and TDF concentration levels in scalp hair samples collected at each visit.

CEI Intervention:

Incentive amounts were guided by a grading system using laboratory- based validated cutoff points. [Table 1] Conditional incentives were administered in the form of supermarket vouchers.