Mentalization for Offending Adult Males (MOAM)

Background: Violent crime is associated with a range of negative impacts on health and wider society. Antisocial personality disorder (ASPD), a key contributor to violent criminal behaviour, is significantly overrepresented among offenders; it carries high rates of comorbidity and mortality for individuals, and high risk of harm to the public. NICE guidelines and Cochrane reviews highlight a lack of evidence for effective interventions for ASPD and urgently recommend research to determine effective and cost-effective interventions for this condition. Our study responds to the gap in the knowledge base by testing the effectiveness of an existing evidence-based treatment in a new target population and context: offenders with ASPD under community supervision. Research Question: Is Probation As Usual (PAU) supplemented with Mentalization-Based Treatment (MBT) more effective and cost-effective than PAU only for reducing aggressive antisocial behaviour and improving wider health outcomes in offenders under community supervision who meet DSM-5 diagnostic criteria for ASPD? Design: A multi-site, two-arm, three-phase randomized controlled trial lasting a total of 66 months, with participants randomly allocated in a 1:1 ratio to receive either PAU only or MBT plus PAU. Setting: National Probation Service (NPS) and partner NHS Trusts at 13 sites across England and Wales. Target population: Male offenders over 21 years subject to statutory supervision by the NPS with at least 6 months remaining of their licence or community sentence, who fulfil DSM-5 diagnostic criteria for ASPD. Sample Size: Our recruitment target is 302 participants; each site is expected to recruit 1 eligible consenting participant per month. This allows for 37% attrition, to end up with 95 participants per arm, yielding 90% power. Health Technology: MBT is a transdiagnostic manualised psychosocial intervention aimed at improving the capacity to use mental state concepts to interpret and organise behaviour. Participants randomised to MBT will receive 12 months of weekly 75-minute group sessions and monthly 60-minute individual sessions; their aim is to stabilise emotional expression and achieve control over aggressive behaviour through increased awareness of mental states that trigger aggressive impulses. MBT will be delivered by NHS and Probation staff and funded by NHS England as part of the National Offender Personality Disorder Pathways Strategy. Outcomes: These will be collected over the 12 months of intervention and the 12-month follow-up period. The primary outcome will be frequency of aggressive antisocial behaviour measured by the Overt Aggression Scale–Modified, collected every 3 months. Secondary outcomes include mental health, quality of life, and offending behaviour, collected every 6 months. Outcome assessments will be conducted by ex-offenders with experience of service user involvement in research. The primary outcome will be analysed using a hierarchical mixed-effects linear regression. Secondary outcomes will be analysed using mixed-effects linear regression, mixed-effects logistic regression models and mixed-effects Poisson models as appropriate. Economic evaluation will be conducted from both a NHS/PSS perspective and a wider societal perspective. Cost-effectiveness analysis will combine data on costs with aggressive antisocial behaviour; cost-utility analysis will combine data on costs with Quality Adjusted Life Years.