A Meta-Analysis on the Effect of Depression on Adherence to Medication for Opioid Use Disorder

Objective: U.S. Food and Drug Administration (FDA)-approved medications for Opioid Use Disorder (MOUD) effectively reduce opioid cravings, use, relapse, and overdose. However, adherence to MOUD is a significant challenge. Depression relates to poorer adherence across several medical conditions and may be a prime factor relating to poor MOUD adherence. The goal of this meta-analysis is to quantify the relationship between depression and MOUD adherence and to identify moderators of this association. Methods: A systematic literature search was conducted using PsycINFO, PubMed, Embase, and Cumulative Index of Nursing and Allied Health Literature [CINAHL] databases. Pearson's r was used for the effect size statistic. A random effects model was utilized for all effect size analyses. Results: Nine studies met eligibility criteria, with a total of 3493 participants. Higher baseline depressive symptoms were found to predict greater prospective adherence to MOUD (r = 0.130, 95% CI: 0.060-0.199, p < .001). This effect was not moderated by the MOUD type or depression measurement type. Conclusions: In contrast to prior medical adherence research, depression predicted better, not poorer, adherence to MOUD. The literature was limited by few studies examining naltrexone, limited diversity of samples, and a lack of clear consensus on adherence measurement. Future research should test whether this relationship extends to naltrexone; use samples with more racial minorities, women and gender minorities, and inpatient samples; clearly define and measure adherence, and identify mechanisms and moderators of this relationship, to best inform future clinical applications and improve outcomes for those with OUD.