We carried out a rapid evidence review to assess the effectiveness and cost effectiveness of peer support for people experiencing problems with alcohol or drug use.

Peer support was defined as support provided by people with lived experience to help others make positive changes in relation to alcohol or drug use.

This review formed part of Public Health Scotland's (PHS) evaluation of the Scottish Government's National Mission on Drug Deaths. It complements a wider study commissioned by PHS and carried out by Glasgow Caledonian University (GCU).

We identified evidence from 10 reviews covering 2 main types of peer support based on recovery-oriented approaches:

• peer-led communities
• peer-based recovery support services (PBRSS)

Key findings

• There was limited or no review-level evidence on the effect of peer support in preventing substance-related deaths.
• There is good evidence that mutual aid groups, particularly Alcoholics Anonymous, support abstinence and reduce substance use.
• There is some review-level evidence that PBRSS can reduce substance use, although findings are mixed.
• PBRSS can help people engage with and remain involved in treatment and support services.
• There is some evidence that peer support can improve recovery-focused outcomes, particularly quality of life.
• There is limited review-level evidence on the impact of peer support on recovery capital outcomes.
• Evidence on the cost effectiveness of peer support is limited. However, the available evidence suggests that mutual aid groups and PBRSS have the potential to be cost effective.