[Rare Diseases and epidemiology: an overlook at data from the Campania Region Rare Disease Registry (Southern Italy)].

Objectives: to provide the epidemiological framework of those affected by rare diseases resident in the Campania Region (Southern Italy), using the data entered in the Campania Region Rare Disease Registry, acquiring information potentially useful for regional planning.

Design: observational retrospective cohort study on patients with rare diseases included in the Regione Campania Rare Disease Registry from 01.01.2022 to 31.12.2022.

Setting And Participants: population included in the Rare Disease Registry and resident in the Campania Region as at 31.12.2022.

Main Outcome Measures: using the data entered in the Regione Campania Rare Disease Registry, the cumulative incidence (I) of patients with rare diseases resident in Campania was calculated, stratified by age group and rare disease group with the respective 95% confidence intervals (IC95%). Standardised cumulative provincial incidences were also calculated. These are reported using a multiplication factor of 100,000.

Results: the incidence of patients with rare diseases in the Campania Region is 50.0 (IC95% 49.4-50.6) per 100,000 inhabitants in the year 2022. Furthermore, the rare disease groups with the highest incidence per 100,000 inhabitants are diseases of the central and peripheral nervous system (I: 8.32 per 100,000 inhabitants) and congenital malformations, chromosomopathies and genetic syndromes (I: 8.52 per 100,000 inhabitants). Moreover, the age groups in which the incidence is highest are in the paediatric age group.

Conclusions: an epidemiological framework of the Campania Region on rare diseases such as this one for the year 2022 is fundamental for national and regional planning in order to improve the care and quality of life of people affected by rare diseases, who often feel neglected by society. Sharing this type of information also draws attention to the need for faster diagnosis and the specialisation of new centres.