JMIR Publications

ABSTRACT

Background:

Women who inject drugs (WWID) are disproportionately impacted by HIV. Pre-exposure prophylaxis (PrEP) could dramatically decrease HIV acquisition, however WWID experience multi-level barriers to engaging in PrEP care, including historical and ongoing trauma. Expressive writing (EW) is a trauma-informed, exposure-based intervention that improves mental health outcomes. Contingency management (CM) is an evidence-based intervention that promotes health behavior change. This randomized controlled trial of “Trauma Intervention for Affect Regulation, Adherence, and Substance Use (TIARAS)” will test the efficacy of EW+CM on HIV risk reduction among WWID.

Objective:

The first objective is to compare the efficacy of EW + CM versus an active attention-control condition (neutral writing [NW] + CM) with respect to HIV risk reduction (at 3, 6, and 12-months after randomization). The second objective is to examine secondary outcomes including: mental health (anxiety, depression, and PTSD), engagement in drug treatment and substance use, as well as cost-effectiveness. The third objective is to evaluate the pathways through which the intervention operates using qualitative interviews, mediation analysis (e.g., emotional expression and processing in EW essays) and moderation analysis (e.g., more pronounced among those with higher PTSD severity at baseline).

Methods:

TIARAS began recruiting in June 2022 and has enrolled 219 adult WWID (≥18 years) receiving a PrEP prescription in the past 4-weeks from a harm reduction agency in Philadelphia (PA, USA). Once enrolled, participants began a 3-month CM protocol that provides cash incentives for objectively verified PrEP adherence and abstinence from opioids and/or stimulants. After a run-in period, participants are randomized 1:1 to the experimental condition (four EW writing sessions plus CM) or the attention-control condition (four neutral writing sessions plus CM). Follow-up data are collected at 3, 6, and 12 months with interviewer-administered surveys, health records, and biological specimen, and with in-depth interviews collected at 3 and 12 months for a subsample of WWID from each intervention group. The primary outcome is HIV risk reduction, operationalized as “reduced” when engaging in syringe sharing or condomless sex during objectively measured periods of PrEP non-adherence and “not reduced” for all other combinations of behaviors during periods of non-adherence. Intent-to-treat analyses will examine the efficacy of EW+CM on HIV risk reduction, mediation of efficacy through mental health (i.e., PTSD symptom severity) and/or polysubstance use, and moderation of efficacy based on social structural determinants of health (e.g., homelessness) and incident traumatic exposures (e.g., arrest, physical assault).

Results:

As of October 2025, TIARAS closed to enrollment and has an anticipated end date in December 2026. Women have been enrolled in equal proportions to both study conditions (n = 95 and 93, for expressing and neutral writing, respectively. Blinding has been maintained, and statistical analyses for the primary and secondary outcomes have not yet been performed.

Conclusions:

We anticipate that the results of our trial will address a critical gap in the literature by advancing our mechanistic understanding of the potentially bidirectional relationships among mental health, polysubstance use, and HIV risk reduction. Clinical Trial: Trial registration: ClinicalTrials.gov number NCT05192434, protocol and statistical analysis plan registered January 14, 2022.