Dr Nicola Metrebian is a Reader in Addiction Treatment Research at the National Addictions Centre, King’s College London. Nicola has a background in Psychology and a PhD from Imperial College London. She has 20 years’ experience in addiction research undertaking large, complex, clinical trials to assess the effectiveness of pharmacological and behavioural interventions. Her research focuses on improving treatment and reducing harms for individuals with opioid use disorder and/or other substance use problems. This includes developing and evaluating Contingency Management (CM) interventions delivered face-to-face and remotely by mobile SMS or app to improve health outcomes, medication adherence and naloxone carriage.

Abstract

Improving treatment attendance, engagement and outcomes for people with dual diagnoses of psychosis and substance use problems: A cluster randomised feasibility study of contingency management and peer support (COMPEERS)

Aims: Dual diagnosis of psychosis and substance use problems is linked to poor treatment attendance and engagement. National Institute for Health and Care Excellence recommended evaluating contingency management, peer support, and text messaging to improve engagement. This feasibility study assessed the potential for a future trial examining whether contingency management can increase attendance at peer support appointments and improve engagement among people with dual diagnosis of psychosis and substance use problems.

Methods: Using a cluster randomised trial design, six community mental health teams were recruited and randomly allocated (1:1) to either: (1) peer support and text messaging with contingency management; or (2) peer support and text messaging with no contingency management. Peer support workers were trained in peer support delivery; those at contingency management sites received additional contingency management training. A patient with lived experience and public involvement and engagement group advised the study.

Results: Between September 2024 and July 2025, 183 patients were screened across six clusters, with 42 enrolled (41 analysed). Thirteen of 18 peer support workers (72%) participated, and 85.7% delivered contingency management adequately. Twelve-week outcome data were available for 36.6% of participants. Seven progression criteria were assessed using a traffic light system and were mainly rated amber or green, except baseline clinical information, which was rated red.

Conclusions: Findings support progression to further trial development, with targeted adjustments. It was feasible for peer support workers to deliver contingency management and qualitative interviews suggested that both peer support workers and service users found contingency management to be acceptable. A future study would benefit from a strengthened recruitment strategy for service users and more reliable baseline clinical information collection.