Background: Pre-exposure prophylaxis (PrEP) with sufficient adherence prevents HIV infection. Challenges to appropriate PrEP use include low uptake, poor adherence, and early discontinuation. The community-based Combination Prevention Effectiveness (COPE) study aims to address these challenges for HIV-uninfected young (18-26) men who have sex with men (MSM) and transgender women (TGW) who exchange sex in urban Thailand. We describe the unique implementation protocol and analytic plan for this open-label, non-randomized, community-based intervention
Methods: YMSM and TGW in Bangkok, Thailand who self-report selling/exchanging sex in the previous 12 months are recruited through peer referral and convenience sampling in venues and online. In-person surveys and biologic testing occur at baseline and every 3 months, and all participants receive brief weekly behavioral SMS surveys. Participants have the option to start PrEP or stop PrEP at any time during the course of the study. During periods of PrEP use, participants pick up pills on a monthly basis, may opt-in to receiving SMS reminders, and receive weekly SMS adherence surveys. HIV incidence during time on-PrEP and time off-PrEP are compared to estimate the intervention effect. Marginal structural models are used for statistical analysis to adjust the estimate for time-varying confounders.
Results: To date (January, 2019), 290 participants have contributed approximately 116 person-years with 94% retention. A total of 272 participants (94%) initiated PrEP at baseline, 26 initiated after baseline, and 10 discontinued PrEP use. Self-reported adherence is high, with 81% taking 7 pills and 17% taking 4-6 pills in the last 7 days. Adherence will be measured through tenofovir diphosphate in dried blood spots. Monitoring of unexpected events has identified some social harms, predominantly related to unintentional participant disclosure of PrEP use and peer stigmatization of PrEP and HIV.
Conclusions: The vast majority of MSM and TGW who exchange sex and participate in this study are interested in PrEP, report taking sufficient PrEP, and stay on PrEP, though additional efforts are needed to address community misinformation and stigma. This novel open-label study design and analytic plan will allow evaluation of the effectiveness and cost-effectiveness of combination prevention intervention in the context of organized sex work and exchange sex.

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