The CTN Prescription Opioid Addiction Treatment Study (POATS, CTN-0030) was the first large, multi-site randomized trial of buprenorphine-naloxone for prescription opioid dependence. At the end of this trial, nearly half of participants met the threshold for successful opioid treatment outcomes, supporting the effectiveness of medication treatment for opioid use disorder (OUD).
Once this study was completed, secondary analyses of the data began to examine factors that might best predict successful opioid use treatment outcomes. Somewhat surprisingly, a diagnosis of lifetime major depressive disorder (MDD) was found to be the best predictor of positive outcomes in the trial, above and beyond other factors like age, route of administration, and previous treatment for OUD.
This finding seems counterintuitive, given the fact that depression is generally linked to poorer outcomes in substance use disorders and has even been found to predict opioid use over time.
This study aimed to take a closer look at the data and assess two theories as to why a history of MDD diagnosis might predict good outcomes for prescription opioid-dependent patients treated with buprenorphine-naloxone: first, that a reduction in depression symptoms would account for the association; and second, that greater motivation and engagement in treatment was the explanation.
Results of the analysis revealed that although depressive symptoms decreased significantly throughout treatment, this improvement was not associated with opioid outcomes. Reporting a goal of opioid abstinence at treatment entry was also not associated with outcomes, however, participation in mutual-help groups was. In each of these models, lifetime MDD remained associated with positive outcomes.
Conclusions: This secondary analysis examined pathways from major depression to treatment outcomes for prescription opioid use disorders and found limited evidence that the two hypothesized mechanisms of change in depression symptoms and motivation could explain the positive effect of MDD diagnosis on treatment outcomes. Findings did, however, demonstrate the benefit of attendance at mutual-help groups. Future research is needed to understand how recovery from opioid use disorder may contribute to changes in depressive symptoms over time.