Aims To identify healthcare transition models associated with positive outcomes, and review evidence regarding the optimum age of transfer and the value of existing age-appropriate services.

Methods A systematic search strategy was used across multiple databases to identify systematic reviews addressing three review questions. 1. What is the evidence for delayed transition? 2. What is the value of existing age-appropriate services? 3. Which aspects/components of transition models are associated with positive outcomes? Reviews that were not systematic, did not cover healthcare transitions, did not concern long-term conditions, or were not reviews of primary literature were excluded. Reviews of quantitative, qualitative or mixed method studies were included. Quality was assessed using the R-AMSTAR tool. Studies with a score below 22 were excluded.

Results The search strategy produced 292 results with 19 systematic reviews meeting all inclusion criteria. The primary studies within these reviews were predominantly qualitative and descriptive studies, with few intervention studies.

Many studies stated that transition time should be determined by the developing maturity of the young person, not by age. However, later transition age was associated with better outcomes. Within the studies, various models of age-specific services for adolescents and young adults were showcased.

The majority of studies assessed these services qualitatively and identified a higher rate of patient satisfaction for age-specific services. Some quantitative studies reported no difference in outcomes, but several noted better outcomes in age-specific services (including improved disease management, lower mortality and reduced costs).

A narrative review of the key components and barriers to effective transition highlighted consistent themes across the literature. Adequate planning (especially with multidisciplinary input); teaching patients healthcare skills; and specialist training for healthcare staff, were identified as key components. Conversely, fragmented healthcare systems, lack of age-appropriate services, and poor continuity were frequently cited as barriers to successful transition.

Conclusions This review suggests that delayed transition and dedicated age-appropriate services result in improved outcomes and increased patient satisfaction. However as fragmented healthcare provision is considered a barrier to successful transition, it is vital that these services are integrated as part of a smooth continuum of care between paediatric and adult services.