This systematic review describes the influence of co-occurring substance use on the effectiveness of opiate treatment programs. MEDLINE/PubMed, Embase, PsychINFO, and the Cumulative Index to Nursing and Allied Health Literature were searched from database inception to November 28, 2018, to identify eligible opioid treatment studies in the United States that assessed the relationship between co-occurring substance use and treatment outcome (i.e., opioid abstinence and treatment retention). A total of 34 eligible studies were included. Overall, co-occurring substance use was associated with negative treatment outcomes regardless of intervention type. However, patterns varied by substance and intervention type. In particular, co-occurring use of cocaine or marijuana with opioids was associated with reduced treatment retention and opioid abstinence regardless of intervention type. Co-occurring use of amphetamines, compared with no use or reduced use of amphetamines, decreased treatment retention. Co-occurring use of alcohol was both positively and negatively associated with treatment outcomes. One study reported a significant positive association between sedative use and opioid abstinence. Generally, findings suggest that combined interventions reported better health outcomes compared with pharmacological or behavioral intervention studies alone. The findings of this review emphasize the need to comprehensively study and address co-occurring substance use to improve opiate treatment programs.
Keywords: behavioral intervention; co-occurring substance use; opiate treatment programs; opioid abstinence; opioids; pharmacological intervention; polysubstance use; treatment retention.
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