# Pre-exposure prophylaxis (PrEP) and medications for opioid use disorder for persons who inject drugs: the CHORUS + randomized controlled trial study protocol

## TL;DR

This study tests a peer recovery coaching program to improve HIV prevention and opioid treatment uptake among people who inject drugs.

## Contribution

The study introduces a novel peer-delivered, smartphone-supported intervention to address HIV prevention and opioid use disorder.

## Key findings

- The CHORUS+ intervention will be tested for its effectiveness in increasing PrEP and MOUD initiation and adherence.
- Adherence to PrEP will be measured using drug levels, prescription refills, and self-report assessments.
- The study will explore mediators like HIV risk perception and knowledge to understand adherence pathways.

## Abstract

Human immunodeficiency virus (HIV) cases among people who inject drugs increased during the US overdose crisis. Although HIV pre-exposure prophylaxis (PrEP) decreases HIV acquisition, and medications for opioid use disorder (MOUD) reduce overdose deaths, uptake remains suboptimal. The CHORUS + study will test the efficacy of a comprehensive peer recovery coaching intervention to increase PrEP and MOUD initiation and adherence.

This two-arm RCT will enroll 284 people who inject opioids (PWIO) and are negative for HIV from two sites. Participants randomized to the CHORUS + intervention will receive a study smartphone, motivational interviewing sessions, assistance connecting to PrEP and/or MOUD, and support to access resources addressing social needs such as employment and housing. We will also incorporate adapted ‘Life-Steps for PrEP’ modules to increase adherence. The control arm will receive information on local organizations with access to PrEP and MOUD. Participants will complete assessments at baseline, 1-, 3-, 6-, and 12-month visits. The primary outcome is adherence to HIV PrEP, assessed by tenofovir-diphosphate drug levels at 6-months post enrollment. Secondary outcomes include PrEP adherence assessed at 3- and 12-months, measured by drug levels (3-months), prescription refills, and self-report; and MOUD receipt at 3-, 6-, and 12-months, measured by prescription refills, self-report, and urine toxicology. The primary analysis will employ intent-to-treat logistic regression to assess differences in adherence between treatment arms, adjusting for stratification factors including site, race and sex assigned at birth. We will analyze secondary outcomes using similar methods. We will use multilevel growth curve modeling to evaluate changes in adherence over time by treatment group, incorporating random intercepts and slopes to account for individual trajectories. We will use exploratory multilevel structural equation modeling to assess mediators including HIV risk perception and PrEP/MOUD knowledge to understand pathways that may influence adherence.

The CHORUS + intervention integrates a novel, theory-based, peer-delivered, smartphone-supported approach to address HIV prevention and opioid use disorder, while tackling social and structural barriers to care. Findings will inform strategies for linking PWIO to rapid HIV prevention and substance use treatment.

ClinicalTrials.gov number: NCT05769218.

The online version contains supplementary material available at 10.1186/s13722-025-00634-2.