Interventions for methamphetamine use among people on methadone maintenance treatment in Vietnam: a sequential...

Methamphetamine (MA) co-use with opioids has increased in Vietnam, hindering methadone maintenance therapy (MMT) through non-adherence and returning to opioid use. This study reports the primary outcomes of the "Screen, Treat and Retain people with opioid use disorders who use MA in methadone clinics" (STAR-OM) trial to integrate evidence-based behavioral interventions into MMT clinics and reduce MA co-use.

STAR-OM was a sequential multiple assignment randomized trial (ClinicalTrials.gov Identifier: NCT04706624) with two 12-week intervention stages across 15 MMT clinics in Hanoi and Ho Chi Minh City, Vietnam. In the frontline intervention stage, 665 MMT patients who co-use MA were randomized to either a low-intensity frontline intervention of six weeks of contingency management (CM) followed by six weeks of group education, or a high-intensity frontline intervention of 12 weeks of CM. Participants who responded to treatment at the end of the frontline intervention stage-having 4 MA-negative urine drug screens (UDS) out of a possible 4 in Weeks 11 to 12-were reassigned to 12-weeks of theory-based text messaging for maintenance. Within each frontline intervention, those who did not have a treatment response were re-randomized to an adaptive intervention of either Matrix only or Matrix + CM for another 12 weeks. Segmented, two-level mixed effects logistic regression compared intervention effects on testing MA-negative over time.

By Week 25, the low-intensity frontline intervention increased by 15.1% in the expected percentage of MA-negative UDS and the high-intensity frontline intervention increased by 16.9%. The high-intensity condition increased more rapidly in MA-negative UDS than the low intensity condition in the first 12 weeks. Participants who were reassigned to text messaging maintained a high percentage of MA-negative UDS-between 87.9% and 92.4%-from Week 14-25. Those re-randomized to Matrix + CM had a greater increase in MA-negative UDS than the Matrix only condition by 10.1 percentage-points.

The STAR-OM trial provides a model of evidence-based adaptive interventions to reduce MA co-use in patients receiving MMT for opioid use disorder in Vietnam and globally. Consistent exposure to CM predicted greater reductions in MA use, emphasizing the importance of positive reinforcement in substance use intervention. Combining CM with the Matrix model may improve outcomes in those who do not initially respond to CM. Theory-based, unidirectional text messaging may support behavioral maintenance in people who respond to frontline intervention.

This trial was funded by the National Institute of Drug Abuse and National Institute of Mental Health.