Mechanism-informed transition from pediatric to adult care in sickle cell disease: a case study

Healthcare transition (HCT) refers to the shift from a child-centered to an adult-centered model of care, a process that, when well-functioning, can reduce disengagement and improve satisfaction with care. The Six Core Elements (6CE) framework structures HCT services; however, its implementation process remains understudied, limiting its broader applicability. Learning how to effectively implement the 6CE strategies can enhance their application in real clinical contexts. This case study describes the successful implementation of a 6CE-informed transition program for adolescents and young adults with sickle cell disease (SCD), a genetic condition associated with reduced life expectancy. We also propose a mechanism-informed approach to guide future HCT implementation. We created a matrix that mapped the transition program activities and domains to the 6CE. Next, we retrospectively created an implementation research logic model. We used it to build causal pathway diagrams that outlined and mapped the contextual determinants to the implementation strategies and their purported mechanisms. To understand the dynamics of each implementation strategy, we built expert consensus and created a causal loop diagram (CLD) that illustrated the interrelationships among the strategies. Four main strategies were identified, each operated across multiple levels and via different mechanisms: (1) Organizational directives worked through rule-setting to increase mandates regarding HCT, (2) SCD transition team worked through care structuring at the organizational level and increased empowerment at the provider level, (3) Monitoring and evaluation enacted HCT activities through increased goals and planning at the organizational level and action planning at the provider level, and (4) Care co-location activated information exchange between pediatric and adult institutions and enhanced influence in decision-making among providers. CLDs identified dynamic variables of the context that impacted the effect of the strategies and uncovered three key underlying processes necessary to implement and likely maintain the 6CE implementation: capacity development, collaboration, and leadership buy-in. This study identified implementation strategies that facilitated the adoption of the 6CE within a SCD transition program and the mechanisms involved. We developed a mechanism-based HCT model for future empirical testing and refinement, aiming to enhance the transportability and adaptability of HCT services across diverse healthcare settings. Healthcare transition (HCT) frameworks enhance health outcomes for adolescents and young adults; however, their implementation remains challenging due to the multifaceted nature of their components and the multi-level targets they address. Optimizing HCT implementation requires a deeper understanding of how implementation strategies function and produce outcomes. Using a sequential approach that combined causal pathways and causal loop diagrams, we retrospectively identified four key implementation strategies and elucidated their underlying mechanisms. We propose a mechanism-informed model for implementing the Six Core Elements of HCT, detailing how implementation strategies contribute to the successful implementation of these elements.