Protocol of a randomized controlled trial examining psychosocial enhancement and standard medication treatment for co-occurring opioid use and mental health disorders: A half fractional factorial randomized controlled trial.

This randomized controlled trial will help determine the effectiveness of MISSION (or its parts) and MOUD compared to TAU to improve engagement in treatment, substance use, and mental health symptoms. This trial is the first to compare MISSION and its parts with MOUD versus TAU in a real-world treatment scenario to determine which components are necessary and sufficient to drive treatment outcomes according to patient needs.