Contingency Management for PrEP Adherence and/or Methamphetamine UseDisorder Among MSM and TW in Los Angeles: A Pilot Feasibility Study

Background

The intersection of substance use, sexual behavior, and HIV transmission in the social and sexual networks of crystal methamphetamine (MA)-using men who have sex with men (MSM) presents a critical public health problem. MA use increases risk for HIV acquisition and transmission in an interwoven series of behavioral, biological, and social mechanisms. Behaviorally, MA use stimulates pleasure-seeking behavior, increasing the likelihood of high-risk sexual contacts and impairing adherence to tools like condoms, pre-exposure prophylaxis (PrEP), and Treatment as Prevention (TasP). Biologically, MA affects immunologic factors associated with HIV-1 transmission, including viral replication, inflammatory cytokine production, T-cell activation, and recruitment of CD4+ T-cells to rectal mucosa. Socially, MA use negatively impacts the perceptions of interpersonal commitment and social cohesion central to community norms of HIV prevention, while elevating the incidence of untreated HIV/STIs in the population and increasing risks of exposure for sexual network contacts. Efforts to address these problems have typically prioritized either reducing MA use or controlling HIV transmission, without targeting the overlapping space between the two problems and exploring how individual-level interventions targeted to high-risk networks can transform community-scale outcomes.

Contingency Management (CM) has been shown to control MA use among habitual users. Adapting principles of behavioral economics, CM addresses the prioritization of short-term rewards and the devaluation of long-term risks commonly seen with MA use. While behavioral approaches like Cognitive Behavioral Therapy have been evaluated as strategies to manage stimulant abuse, these methods have not shown independent benefit in modifying patterns of drug use, presumably because they do not intervene in the cognitive risk-reward feedback loop that underlies stimulant abuse and that is replaced by CM incentives. Analysis of previous clinical trial data suggests that the small financial incentives provided in exchange for stimulant-free urine may substitute for the short-term feedback loops that structure the cognitive processes of habitual MA users, and serve as an essential component in CM's success.

The potential indirect effects of CM on HIV transmission have been evaluated in several studies. In conjunction with reduced MA use, MSM often report a corresponding reduction in frequency of condomless intercourse. However, efforts to implement CM as a harm reduction strategy in sexually transmitted infection (STI) clinics have been unsuccessful, leading to questions about how it can be applied to real world settings. In these contexts, incremental improvements among individual MA users are often insufficient in modifying problems like frequency of condomless intercourse, adherence to antiretroviral therapy (ART), and network-level patterns of HIV and STI transmission. The goal of the current research is to use CM as a platform to integrate HIV prevention with substance use treatment among MA-using MSM to transform population-level patterns of HIV transmission.

Specific Aims Aim 1. To assess the logistics, feasibility, and acceptability of a point-of-care urine assay to assess short-term adherence to Tenofovir (TFV)-based antiretrovirals (ARVs) or PrEP regimens among MA-using MSM. The investigators plan to enroll 10 HIV-infected and 10 HIV-uninfected MSM with recent use of MA and a tenofovir-based HIV treatment or prevention regimen. Participants will be randomly assigned to traditional CM (Arm A) or ARV-based CM (Arm B) and asked to attend monitoring visits three times per week over a 30-day period. Each visit will include urine monitoring for recent MA use and ART adherence (in both Arms). At each visit where a participant's urine either does not contain MA (Arm A) or does contain tenofovir (Arm B), they will receive a small financial incentive. Incentives will gradually increase with each successful urine test, or they will reset to zero if the participant fails the urine screen or misses a visit. Aim 1 outcomes will assess participant retention, satisfaction and acceptability of the CM format for supporting ARV adherence.