Background: Opioid use disorder (OUD) is a growing health crisis in the United States (US). Buprenorphine treatment for OUD has been found to improve outcomes and reduce mortality, although disparities in access to treatment and outcomes for OUD exist. Previous studies have shown that those retained in treatment for longer durations are more likely to have better long-term outcomes, however over half of individuals discontinue treatment within the first six months. Notably, there is little understanding of how social determinants play a role in retention in treatment. The objective of this work was to assess the association between social determinants and buprenorphine treatment retention among US adults.

Methods: A systematic review with literature obtained from MEDLINE and Embase were included in this analysis. Inclusion criteria were adults >18 treated for OUD in the outpatient settings in the US. Included studies had to measure at least one social determinant (i.e. education, socioeconomic status, employment status, food insecurity, rural vs urban environment, housing insecurity, social support, insurance status, race/ethnicity, co-occurring substance abuse, drug of choice). Included studies also had to measure the outcome of retention in treatment. Only observational studies published in 2000 or later with full text published in English were included. We used the Newcastle-Ottawa Scale for risk of bias assessments and the GRADE framework for strength of evidence assessments. We report a narrative synthesis, with no pooling of results, because of significant heterogeneity among exposure and outcome measures.

Results: A total of 17 articles were included in this analysis. There was moderate strength of evidence that living in an urban area, identifying as Black or Hispanic, and having co-occurring substance use was associated with decreased duration of treatment. Strength of evidence was low for the remaining social determinant exposures.

Conclusions: Although previous literature has found that those living in rural areas have less access to treatment initiation, our findings suggest that those living in urban areas are at higher risk of early treatment discontinuation. Additionally, our findings showed those who are Black or Hispanic and those with co-occurring substance use are at increased risk for treatment discontinuation. This further elucidates previous research which showed disparities in OUD treatment outcomes among these groups. Limitations of this work include heterogeneity among exposures and outcomes between studies, which limited our ability to directly compare study results. Additionally, there were gaps in the literature, preventing assessment of factors such as food insecurity or socioeconomic status.