Abstract
Healthcare transition from pediatrics to adult care is a critical yet challenging process for adolescents with long-term medical conditions. This population-based cohort study aims to present a replicable method to identify and quantify adolescents in need of comprehensive transitional care. Using data from Danish national health registers, disease complexity was categorized by expert clinicians based on diagnoses indicative of a need for comprehensive transitional care and transfer to specialized adult healthcare. The study identified 4,677 adolescents requiring comprehensive transitional care from a background population of 418,994 Danish adolescents aged 16-17 years, corresponding to 1.1%. Analysis of outpatient visit data from tertiary hospitals revealed variability in the proportion of adolescents with comprehensive transitional care needs across Denmark's four tertiary hospitals. For instance, 11.6% of outpatient visits at Aalborg University Hospital involved a comprehensive transition-requiring diagnosis, compared to 26.7% at Copenhagen University Hospital. While the method is intentionally specific and focused on adolescents with the most complex conditions, it offers a scalable framework that could be applied across broader clinical settings. We illustrate this by also applying the method within a pediatric department-based setting. This study provides al replicable framework to assess transition care needs at a population level, primarily identifying adolescents with the most complex conditions. Broader implementation across clinical settings may refine and inform equitable transitional strategies.