Therapy Dose Mediates the Relationship Between Buprenorphine/Naloxone and Opioid Treatment Outcomes in Youth Receiving Medication for Opioid Use Disorder Treatment

Background: Evidence-based interventions for treating opioid use disorder (OUD) in youth are limited and little is known about specific and general mechanisms of OUD treatments and how they promote abstinence. Methods: The present study used data from the NIDA-CTN-0010 trial to evaluate the mediating effects of psychosocial treatment-related variables (therapy dose and therapeutic alliance) on end-of-treatment opioid abstinence in a sample of youth with OUD (n = 152, 40% female, mean age = 19.7 years) randomized to receive either 12-weeks of treatment with Bup/Nal ("Bup-Nal") or up to 2 weeks of Bup/Nal detoxification ("Detox") with both treatment arms receiving weekly individual and group drug counseling +/- family therapy. Results: Participants in the Bup-Nal group attended more therapy sessions (16 vs 6 sessions), had increased therapeutic alliance at week-4, and had less opioid use by week-12 compared to those in the Detox group. In both treatment arms, youth who attended more therapy sessions were less likely to have a week-12 opioid positive urine. In a multiple mediator model, therapy dose mediated the association between treatment arm and opioid abstinence. Conclusions: These findings provide preliminary support for a "dose-response" effect of addiction-focused therapy on abstinence in youth OUD. Further, the results identified a mediating effect of therapy dose on the relationship between treatment assignment and opioid treatment outcomes, suggesting that extended Bup-Nal treatment may enhance abstinence, in part, through a mechanism of therapy facilitation, by increasing therapy dose during treatment.