Outreach and Support in South London for Bipolar At-Risk States: pilot implementation of a specialist preventive service for adolescents and young adults at risk of developing bipolar disorders.

Bipolar disorders (BD) are associated with high disability, comorbidities, and premature mortality, yet diagnosis is often delayed by several years. Research has identified bipolar at-risk states (BARS), but no study has tested the feasibility and acceptability of a dedicated specialist service. Consequently, evidence is lacking on optimal service set up, outreach strategies, and referral pathways required to effectively implement a BD prevention service. Outreach and Support in South London (OASIS)-BAR was piloted for 18 months as the first National Health Service (NHS)-funded standalone specialist service for individuals at risk of BD. The service, co-designed with experts by experience, operated in Lambeth, London, a socially deprived and ethnically diverse borough. Feasibility was evaluated through service set up, efficiency (outreach performance, waiting times, detection rates, treatment provision), and continuity of care (successful discharge planning). Acceptability was assessed through service engagement and qualitative feedback from service users and stakeholders. Of 28 referrals, 17 were assessed and 10 (58, 8%) met SIBARS criteria. The mean waiting time from referral to complete assessment was 22.4 days. All service users received medical reviews (100%), while most received psychotherapy (66, 7%) and occupational support (77, 8%). Engagement was satisfactory (mean length = 271 days). Service users expressed high satisfaction, and professional stakeholders emphasised the service's role in addressing unmet needs and alleviating caseload burden on other services. OASIS-BAR pilot implementation demonstrated the feasibility and acceptability of a standalone service for BD prevention within the NHS. Findings support the development of similar innovative services, which may strengthen early detection and preventive care, ultimately improving long-term outcomes for many young people.