[Italian Cystic Fibrosis Registry (ICFR). Report 2021-2022].

Introduction: Italian Cystic Fibrosis Registry (ICFR) collects data of patients with cystic fibrosis (CF) through the collaboration with Italian CF referral and support Centres (Italian law 548/93). It aims at analysing medium and long-term clinical and epidemiological trends, identifying healthcare needs at regional and national levels, contributing to healthcare programmes, and resource allocation. Italian data are also compared at international level through the collaboration with the European CF Registry for sharing epidemiological data on general aspects like CF epidemiology and specific topics such as the use of CFTR modulators.

Objectives: The purpose of this Report is to provide updated demographic and clinical data of the Italian FC population for the years 2021 and 2022, to contribute essential information for the implementation of projects aimed at improving the management of patients affected by this disease.

Design: Analyses and results presented in this Report pertain to patients currently under care at Italian National Referral and Support Centres for Cystic Fibrosis and Paediatric Hospital 'Bambino Gesù' in the 2021-2022 period. Data were submitted by clinical Centres through a dedicated web-based software and underwent dual quality control (QC) measures: automated quantitative QC within the software and secondary QC at the European level before the integration into the European Cystic Fibrosis Registry. These measures ensure data completeness, accuracy, and longitudinal consistency with European core data.

Setting and participants: A total of 27 CF Centres, including referral and support centres, as well as 'Bambino Gesù' Children's Hospital CF centre, submitted their data to ICFR for the years 2021-2022. Althourgh CF Centres in Verona and Messina do not use the ICFR software, their data are centrally collected and subsequently forwarded to the European Registry. Data from service centres in Treviso and Rovereto are transmitted via the Verona CF Centre. Data from Sardinia Centre are currently unavailable.

Results: The results section provides a comprehensive overview of various aspects of CF epidemiology and patient characteristics. 1.Demography: in 2021 and 2022, 5,977 and 6,077 CF patients were respectively included in the ICFR, with median ages of 23.3 and 23.7 years. The prevalence rates were 10.1 and 10.3 per 100,000 residents in Italy for the respective years, with males comprising 51.6% on average. The distribution by age showed a higher frequency among patients aged 7 to 35 years; adult patients constituted 63.5% on average in both years. 2. Diagnosis: most CF patients were diagnosed before the age of two (mean value 57.9%), with a significant percentage diagnosed in adult age (35.4% in 2021 and 25.6% in 2022). 3.New diagnoses: there were 113 new diagnoses in 2021 and 121 in 2022, with estimated incidences of 1 in 9,097 living births in 2021 and 1 in 6,232 in 2022. 4. Genetics: genetic analyses were conducted on 99.9% of patients, revealing CFTR gene mutations in over 98% of cases. The F508del mutation was the most common (44% of alleles in 2021), with 18% of patients having at least one "residual function" mutation. Gating mutations were present in 3.4% of Italian patients, while 20% had at least one-stop codon mutation. 5.Lung function: lung function, measured by percent predicted (pp)FEV1 (Forced Expiratory Volume in the first second) progressively declined before adulthood, with the majority of paediatric patients (92.8% in 2021 and 93.8% in 2022) maintaining a ppFEV1≥70%. 6.Nutrition: critical periods for nutrition were identified as the first 6 months of life and adolescence, with higher prevalence of malnourished male adolescents compared to females. Suboptimal BMI values were more common in adult females (28.7% in 2021 and 26.9% in 2022) compared to males (14.2% in 2021 and 12.6% in 2022). 7. Complications: CF-related liver disease without cirrhosis was prevalent in patients under 18 years (21.9% in 2021 and 21.2 in 2022), while CF-related diabetes was most frequent in adults (24.2%). 8.Transplantation: over the two-year period, 28 patients underwent double-lung transplantation, with median ages of 29.1 in 2021 and 35.3 in 2022, respectively. Median waiting times ranged from 9.4 to 11.6 months. 9.Microbiology: chronic Pseudomonas aeruginosa infection affected 37.2% of adult patients in 2021 and 36.0% in 2022, compared to 7.4% and 6.5% in paediatric patients. Staphylococcus aureus infection rates were 34.6% and 42.2% in 2021 among adults and 34.4% and 36.7% in 2022 among paediatric patients. 10. Mortality: a total of 34 patients died during the 2021-22 period (19 females, 15 males), with median ages at death of 43.7 years in 2021 and 46 years in 2022 (excluding transplanted patients).

Conclusions: The present Report is an update of the data published in the past years and summarizes the main epidemiological and clinical data regarding Italian CF subjects in the years 2021 and 2022. The number of patients registered in 2021 was 5,977, while in 2022 was 6,077. The population coverage estimates for 2022 to be around 97%. In 2020, 60.5% of patients were older than 18 years, in 2022 adult patients account for 63.5% of the Italian CF population. Over the years, therefore, an increase in the median age of Italian CF patients has been observed, reaching 23.7 years in 2022. The absolute number of new diagnoses per year remains substantially unchanged over the years (a total of 234 in the period under review). The median age at diagnosis in 2022 was 2.5 months, 62.6% of subjects are really diagnosed within the first year of life and almost 90% of them are diagnosed through neonatal screening. In 2022, almost all patients underwent genetic analysis (99.9%). Data collected confirm the great variability among Italian CF patients. As regards respiratory function, what is reported in previous reports is here confirmed, with an ever-increasing percentage of subjects under the age of 18 having normal respiratory function, moreover, less than 1% of paediatric patients has a severe lung function (ppFEV1<40). The marked improvement in this indicator in the adult population seems to be mainly due to the introduction from 2021 in Italy of therapy with highly effective CFTR modulators. At the same time, the close positive correlation between nutritional status and respiratory function is confirmed for the adult population. As regards chronic infection by Pseudomonas aeruginosa, in 2022, a reduction in the percentage of chronic infection is observed both among adults (36% vs 38.8% in 2020) and in paediatric patients (6.5% vs 7.6% in 2020). The most frequent complication in both paediatric and adult populations is liver disease (respectively, in 24.2% and 41.3% of subjects). In the two-year period, 34 patients died; their median age at death was between 43 and 46 years (transplant patients excluded); only two patients under the age of 18 died in the period 2021 and 2022, confirming once again that mortality in paediatric age is a rare event. The data presented in this Report shows how the register can be a national and international point of reference for CF patients and the scientific community, a tool for describing the Italian CF population over the years, and a starting point for planning epidemiological studies and clinical studies.