Bridging the medical cliff: a paediatric-adult continuity of care model for 2,341 young adults with rare diseases in China.

Introduction: Adolescents and young adults with rare diseases face a "medical cliff" when they age out of paediatric services, losing established care relationships and disease-specific expertise. Most rare diseases begin in childhood, since 69.9% of catalogued rare diseases are of exclusively paediatric onset. The problem is acute in China, where an estimated 20 million people live with a rare disease and systematic transitional care pathways remain largely absent. Methods: We describe the development and implementation of an integrated paediatric-adult continuity of care model for rare diseases, the adult population it serves, and early operational indicators of its feasibility. This retrospective, descriptive analysis used clinical service data from the Children's Hospital of Fudan University, Shanghai, over a 38-month window (3 January 2023-25 February 2026); the model was implemented from September 2023. Its four components were expanded treatment authority with proactive management; a multidisciplinary paediatric-adult joint clinic; proactive follow-up with dynamic evaluation; and medical social work with psychosocial support. The programme admits patients aged 18-35 years. Results: In total, 2,341 patients aged ≥18 years generated 4,847 outpatient, emergency, and inpatient encounters (mean age at first encounter 22.7 ± 5.9 years; 51.7% female). Annual encounter volumes rose from 240 in 2023 to 1,412 in 2024 and 2,628 in 2025, with a further 567 in January and February 2026. Return attendances accounted for 4,373 encounters (90.2%), and 843 patients (36.0%) attended more than once. The leading specialities were neurology (29.1%), hepatology (12.2%), and endocrinology (8.1%); most encounters were by Shanghai residents (54.8%). Discussion: Repeat attendance measures utilisation rather than adherence, and rising volumes likely reflect progressive implementation and growing awareness rather than model effectiveness. With enabling policies, paediatric hospitals can deliver continuous care for adult rare disease patients, although these indicators describe service activity rather than clinical or patient-reported outcomes. The model is best characterised as continuity of care delivered within paediatric services rather than as a conventional transition programme, and offers a replicable blueprint for health systems lacking established adult subspeciality services; cross-provincial health insurance portability remains the single most critical barrier to nationwide scale-up.