Effectiveness of peer recovery support services on stages of the opioid use disorder treatment cascade: A systematic review.

Background: Peer recovery support services (PRSS) have been increasingly incorporated during the recovery process for opioid use disorder (OUD), yet little is known about the effects of PRSS on clinical outcomes of individuals who misuse opioids. This study systematically synthesized existing literature reporting the effectiveness of PRSS interventions on stages of the OUD treatment cascade.

Methods: A search conducted on five databases identified studies from database inception to January 26th 2021 that evaluated the effects of PRSS on PRSS engagement, medication for OUD (MOUD) initiation, MOUD retention, opioid and non-opioid misuse, and remission. Characteristics of PRSS interventions, study design, and clinical outcomes were extracted. Methodological quality was assessed with the quality assessment tool for quantitative studies by the Effective Public Health Practice Project.

Results: Of 123 titles, 22 were subjected to full-text review and 12 ultimately met inclusion criteria. Only two studies were randomized control trials, half compared the outcomes of PRSS participants to those of a counterfactual group. Most PRSS were unstandardized and broadly described, involving linkage to treatment (91.7%) or follow-up support (91.7%). MOUD initiation was reported the most often (66.7%), followed by PRSS engagement (33.3%) and opioid use (25.0%). No studies reported findings for MOUD retention or remission. Findings for available outcomes were inconsistent and difficult to compare due to the heterogeneity of PRSS interventions and methodological limitations.

Conclusion: Effectiveness of PRSS interventions on stages of the OUD treatment cascade remain inconclusive. Additional research is necessary before supporting the implementation of PRSS on a broad scale.