Peer interventions for hepatitis C testing and treatment in OECD countries: a systematic scoping review

Services delivered by peer workers (people with lived/living experience) are recommended to find, test and treat those at risk of hepatitis C (HCV). However, there is a lack of knowledge around the characteristics and underlying mechanisms of existing HCV peer interventions and how these drive effectiveness and impact. This systematic scoping review aimed to identify the activities of peer interventions, their reported outcomes and mechanisms of change. We systematically searched five databases (Scopus, PubMed, Embase, PsycINFO and Web of Science) for peer-reviewed papers which described HCV peer interventions in OECD countries published between 2012 and 2022, informed and structured by the PRISMA extension for scoping reviews and scoping review reporting guidance. All identified studies were double screened at title and abstract, and full text stage. Twenty-nine studies met our inclusion criteria. In 23 studies, peer workers delivered interventions, mostly focused on outcomes for intervention recipients. Peer workers improved HCV care linkage, testing, treatment and SVR12 rates. Peer workers themselves reported increased confidence, job satisfaction, improved mental wellbeing, employability and social integration into communities. Key activities and peer intervention elements were occasionally documented, but more often omitted. None of the included studies explicitly documented or theorised underlying mechanisms, i.e., how or why peer interventions work. The lack of details and mechanistic descriptions of peer interventions negatively impact on the ability to optimise and enhance peer-led HCV care and potentially undermines the elimination of HCV at population level.