Background

This study describes the first six years of data collection within the EuRREB Core Endocrine Registry, a multinational platform developed to collect harmonised clinical data on rare endocrine conditions across Europe. The registry supports longitudinal data collection, real-world evidence generation, and international collaboration. Particular attention was given to the transition period from paediatric to adult care (14-25 years), a phase known to present challenges for patients with rare endocrine disorders. The study explores the registry’s potential to generate insights into transition of care and support the development of best practice guidelines.

Objective

To describe the data collected in the EuRREB Core Endocrine Registry during its first six years of operation and to evaluate its potential for studying transition of care among patients with rare endocrine conditions.

Methods

A cross-sectional analysis was performed using data collected in the EuRREB Core Registry between June 2019 and June 2025. The registry collects clinician-reported and patient-reported outcomes from participating centres across Europe and beyond. Data were analysed across eight endocrine Main Thematic Groups (MTGs), with a specific focus on patients aged 14 to 25 years.

Results

Forty-eight centres from 20 countries contributed data, including 33 Endo-ERN centres. A total of 3,225 unique patients were registered, with a median age of 37 years. The hypothalamic and pituitary MTG accounted for the largest number of records (1,548 patients). The highest proportion of patients within the transition age group was observed in the sex development and maturation MTG (66%), followed by thyroid disorders (33%) and growth and genetic obesity disorders (32%). Additionally, 303 patients had access to the patient platform, 85 completed patient-reported outcome measures, and clinicians reported 2,390 condition-specific outcomes. These findings demonstrate the registry’s capacity to generate real-world insights across a wide range of rare endocrine disorders and age groups.

Conclusion

The EuRREB Core Endocrine Registry provides a valuable infrastructure for collecting real-world data on rare endocrine conditions across Europe. The substantial representation of transition-age patients highlights opportunities to strengthen continuity of care between paediatric and adult services. Continued expansion of the registry and international collaboration will support future research, improve understanding of transition pathways, and contribute to evidence-based care for patients with rare endocrine disorders.

Overview Publication