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Heroin Addiction and Related Clinical Problems: 2026, 28: 49-58

Predictors of extended-release naltrexone adherence and relapse: Secondary outcomes from the MAT-PLUS pilot

Julia Thomas, Kevin Wenzel, Jennifer Carrano, Jennifer Stidham, and Marc Fishman

Digital Object Identifier:
https://doi.org/10.62401/2531-4122-2026-7

Summary: Background: Substance use disorders (SUDs), including opioid (OUD) and alcohol use disorder (AUD), are significant public health concerns. Extended-release naltrexone (XR-NTX) is an effective treatment for both, but adherence is low, and interventions addressing adherence issues limited. In a small pilot RCT, the multicomponent MAT-PLUS (Medication Adherence Therapy: Psychosocial Leverage Using a Significant Other) model improved XR-NTX adherence in a sample of patients with OUD and/or AUD. The purpose of this report is to explore baseline participant characteristics that could predict XR-NTX adherence and opioid/alcohol relapse. Methods: We identified 25 variables and examined their relationship with XR-NTX adherence and relapse. Variables that were significantly related to these outcomes in bivariate analyses were included together in multivariate regression models predicting each outcome. Models were iteratively refined using a backwards stepwise approach to identify a final, most parsimonious model for each outcome. Results: Results show that participants with OUD only (vs AUD) receive fewer XR-NTX doses (β= -0.482, p=0.021). Participants were more likely to relapse if they did not use psychotropic medication use before treatment yes/no (OR=0.107, p=0.009) and if they had higher goal success and orientation scores (OR=1.60, p=0.026). Discussion: SUD diagnosis, psychotropic medication use, and goal orientation/success emerged as significant predictors of key SUD treatment outcomes.

Keywords: medication adherence; opioid use disorder; alcohol use disorder; extended-release naltrexone