A peer-delivered intervention to reduce harm and improve the well-being of homeless people with problem substance use: the SHARPS feasibility mixed-methods study.

Background: For people experiencing homelessness and problem substance use, access to appropriate services can be challenging. There is evidence that development of trusting relationships with non-judgemental staff can facilitate service engagement. Peer-delivered approaches show particular promise, but the evidence base is still developing. This study tested the feasibility and acceptability of a peer-delivered intervention, through 'Peer Navigators', to support people who are homeless with problem substance use to address a range of health and social issues.

Objectives: The study objectives were to design and implement a peer-delivered, relational intervention to reduce harms and improve health/well-being, quality of life and social functioning for people experiencing homelessness and problem substance use, and to conduct a concurrent process evaluation to inform a future randomised controlled trial.

Design: A mixed-methods feasibility study with concurrent process evaluation was conducted, involving qualitative interviews [staff interviews (one time point),  = 12; Peer Navigator interviews (three or four time points),  = 15; intervention participant interviews: first time point,  = 24, and second time point,  = 10], observations and quantitative outcome measures.

Setting: The intervention was delivered in three outreach services for people who are homeless in Scotland, and three Salvation Army hostels in England; there were two standard care settings: an outreach service in Scotland and a hostel in England.

Participants: Participants were people experiencing homelessness and problem substance use ( = 68) (intervention).

Intervention: This was a peer-delivered, relational intervention drawing on principles of psychologically informed environments, with Peer Navigators providing practical and emotional support.

Main Outcome Measures: Outcomes relating to participants' substance use, participants' physical and mental health needs, and the quality of Peer Navigator relationships were measured via a 'holistic health check', with six questionnaires completed at two time points: a specially created sociodemographic, health and housing status questionnaire; the Patient Health Questionnaire-9 items plus the Generalised Anxiety Disorder-7; the Maudsley Addiction Profile; the Substance Use Recovery Evaluator; the RAND Corporation Short Form survey-36 items; and the Consultation and Relational Empathy Measure.

Results: The Supporting Harm Reduction through Peer Support (SHARPS) study was found to be acceptable to, and feasible for, intervention participants, staff and Peer Navigators. Among participants, there was reduced drug use and an increase in the number of prescriptions for opioid substitution therapy. There were reductions in risky injecting practice and risky sexual behaviour. Participants reported improvements to service engagement and felt more equipped to access services on their own. The lived experience of the Peer Navigators was highlighted as particularly helpful, enabling the development of trusting, authentic and meaningful relationships. The relationship with the Peer Navigator was measured as excellent at baseline and follow-up. Some challenges were experienced in relation to the 'fit' of the intervention within some settings and will inform future studies.

Limitations: Some participants did not complete the outcome measures, or did not complete both sets, meaning that we do not have baseline and/or follow-up data for all. The standard care data sample sizes make comparison between settings limited.

Conclusions: A randomised controlled trial is recommended to assess the effectiveness of the Peer Navigator intervention.

Future Work: A definitive cluster randomised controlled trial should particularly consider setting selection, outcomes and quantitative data collection instruments.

Trial Registration: This trial is registered as ISRCTN15900054.

Funding: This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in ; Vol. 26, No. 14. See the NIHR Journals Library website for further project information.