Opioid-specific medication assisted therapy (MAT) significantly reduces the odds that justice-involved people will experience non-fatal overdoses. MAT does not appear to reduce the odds of criminal justice outcomes (such as offending, rearrest, reconviction, reincarceration) or fatal overdose, despite some evidence of this in individual studies.

What is this review about?
There is much overlap between people who misuse opioids and those with justice system involvement. Addiction is shown to increase the likelihood of continued justice system involvement and overdose. Criminal justice agencies are therefore under pressure to treat addiction, and MAT is one promising approach specific to opioids. This Campbell systematic review considers the impacts of opioid-specific MAT on rearrest, reconviction, reincarceration, and offending, as well as fatal and non-fatal overdose for justice-involved populations.

What is the aim of this review?
This Campbell systematic review assesses the effects of opioid-specific medication assisted therapy (MAT) for reducing the frequency and likelihood of criminal justice and overdose outcomes for current or formerly justice-involved individuals.

What studies are included?
This review includes 20 studies, of which 14 are experimental and six are quasi-experimental. Though there is some degree of methodological concern across all studies, 16 studies were of sufficient methodological quality, rigour and similarity (e.g., measurement of outcomes) to be included in the meta-analysis. The studies span the years 1999 to 2021, and were carried out in the USA, Canada, Australia, the UK and Norway.

What are the main findings of this review?
There is a significant reduction in the odds of non-fatal overdose for justice-involved people who are treated with MAT. However, there are no significant reductions in the odds of offending, rearrest, reconviction, reincarceration or fatal overdose. These findings are tempered by evidence of poor adherence to study designs and medication regimens.

What do the findings of the review mean?
MAT may be useful to agencies that serve justice-involved people, in conjunction with interventions that target other causes of criminal behaviour and that deliver comprehensive evidence-based substance use treatment services beyond medication. More studies are needed that include strong research designs such as random assignment to treatment or control groups.

Researchers should work with agencies to improve adherence to medication regimens, study design, and to collect more detailed information on study participants, including their demographic information, treatment and criminal histories, medication adherence, and symptom onset and severity. Outcomes should be assessed in multiple ways across the full follow-up period, including from self-reported and official records.