Sustaining the 4 youth by youth HIV prevention intervention in Nigeria: a cluster randomized controlled trial protocol.

backgroundSustaining evidence-based HIV prevention interventions remains a challenge, particularly among at-risk youth in Africa. The 4 Youth by Youth (4YBY) sustainment study is a hybrid type 2 cluster randomized controlled trial that evaluates the sustainability and cost-effectiveness of a crowdsourced approach to sustaining a package of evidence-based HIV prevention services. The study will be conducted across 40 community sites, supported by 18 community-based organizations (CBOs) providing HIV prevention services in Nigeria. Given their longstanding engagement with young people, CBOs serve as key partners in assessing long-term sustainability strategies for the 4YBY intervention, which has proven effective in increasing HIV prevention service uptake among youth.

methodsThis protocol describes a cluster randomized controlled trial that will be conducted across 40 sites, all randomized into two arms. Half of the sites (20) will be assigned to receive the standard 4YBY intervention (4YBY-S), while the other 20 sites will receive the standard 4YBY intervention plus an enhanced sustainability strategy (4YBY-S + 4YBY-E). While the 4YBY-S group will continue implementing core intervention activities, the 4YBY-E group will receive additional sustainability-focused support. The Enhanced Sustainability Strategy in the 4YBY-E arm consists of four key components. First, "People" involves identifying and training sustainability teams within CBOs to champion intervention longevity. Second, "Learning", where bi-weekly collaborative sessions will be established to foster knowledge-sharing and problem-solving among stakeholders. Third, "Adaptation Monitoring" will focus on continuously tracking and modifying intervention strategies to better align with local needs. Finally, "Nurturing Coaches" includes dedicated coaches who will provide technical assistance, conduct audits, and offer feedback to strengthen sustainability efforts. Evaluation will be guided by Youth Participatory Action Research (YPAR), the PEN-3 Cultural Model, Proctor's Implementation Outcomes Framework, and the Consolidated Framework for Implementation Research (CFIR). The study hypothesizes that sites receiving the enhanced sustainability strategy (4YBY-S + 4YBY-E) will exhibit greater sustainability of core intervention components, defined as the continued delivery, adaptation, and integration of the intervention within community-based organizations-compared to sites receiving only the standard 4YBY intervention (4YBY-S). Additionally, the 4YBY-S + 4YBY-E arm is expected to achieve a higher uptake of HIV prevention services at 24 months, reflecting both the intervention's effectiveness and its long-term viability within community settings. DISCUSSION: This protocol represents one of the first cluster randomized controlled trials evaluating intervention sustainment strategies for a youth-led, evidence-based HIV prevention program in Africa. Findings will advance implementation science by establishing a threshold for sustainable strategies and identifying the key factors that support the long-term integration and continuation of HIV prevention services for at-risk youth. The results critically impact scaling up community-led interventions and shaping policy frameworks to strengthen the global HIV response. The protocol was registered with clinicaltrials.gov under registration NCT07072481.