Why Participants Leave: A Qualitative Study Exploring Dropout from a Medication for Opioid Use Disorder (MOUD) Clinical Trial

BACKGROUND: High dropout rates in clinical trials can undermine data validity, particularly among individuals with substance use and mental health disorders. This qualitative study examined reasons for participant dropout from a randomized trial evaluating the Minds and Mentors Program, a Mindfulness-Based Relapse Prevention and peer support intervention, among adults receiving Medication for Opioid Use Disorder (MOUD). METHODS: Using a qualitative descriptive design, semi-structured interviews were conducted with eight participants who withdrew before completing the 12-week intervention or follow-up assessments. Interviews were transcribed verbatim and analyzed thematically following Braun and Clarke's framework. RESULTS: Four themes captured participants' reasons for disengagement: (1) Structural and Logistical Barriers (e.g., work conflicts, transportation issues, and program discontinuation); (2) Procedural Fatigue and Assessment Burden related to lengthy or repetitive questionnaires; (3) Emotional and Relational Triggers tied to distressing group content and perceived stigma; and (4) Perceived Value and Program Continuity, where abrupt endings and unclear outcomes reduced motivation. Despite challenges, participants valued the study's intent and supportive staff. CONCLUSIONS: Dropout in MOUD trials reflects the intersection of individual circumstances and modifiable design features. Implementing flexible scheduling, hybrid participation models, reduced assessment burden, trauma-informed facilitation, and transparent communication may improve retention and ensure participant-centered, equitable research outcomes.