The Italian Registry for Primary Immunodeficiencies (Italian Primary Immunodeficiency Network; IPINet): Twenty Years of Experience (1999-2019)

Abstract

Primary immunodeficiencies (PIDs) are heterogeneous disorders, characterized by variable clinical and immunological features. National PID registries offer useful insights on the epidemiology, diagnosis, and natural history of these disorders. In 1999, the Italian network for primary immunodeficiencies (IPINet) was established. We report on data collected from the IPINet registry after 20 years of activity. A total of 3352 pediatric and adult patients affected with PIDs are registered in the database. In Italy, a regional distribution trend of PID diagnosis was observed. Based on the updated IUIS classification of 2019, PID distribution in Italy showed that predominantly antibody deficiencies account for the majority of cases (63%), followed by combined immunodeficiencies with associated or syndromic features (22.5%). The overall age at diagnosis was younger for male patients. The minimal prevalence of PIDs in Italy resulted in 5.1 per 100.000 habitants. Mortality was similar to other European registries (4.2%). Immunoglobulin replacement treatment was prescribed to less than one third of the patient cohort. Collectively, this is the first comprehensive description of the PID epidemiology in Italy.

Keywords: Primary immunodeficiencies; patient registry.

Fig. 1

PID registration in the IPINet registry. Annual numbers for new (white bars) and patients registered the year before (N-1) (black bars) for the period 1999–2019

Fig. 2

Regional minimal prevalence of PIDs in Italy. Geographic distribution of PIDs in the Italian territory based on patients’ residence (data refer to 2019). Darker shades of gray areas correspond to higher minimal prevalence of PIDs. Data are expressed as minimal prevalence calculated per 10⁵ inhabitants

Fig. 3

PID distribution and characteristics in the IPINet registry. a Overall PID distribution in Italy (percentages) based on the latest IUIS classification (2019). b Detailed PIDs’ distribution in the IPINet registry (number of patients). Patterns identify six groups based on the latest IUIS classification

Fig. 4

Death rate of PID patients in the IPINet registry. a Number and percentages of alive, deceased, and lost to follow-up patients during the 20-year follow-up period (patients lost to follow-up patients without updated data in the registry over the years). b Comparison of IPINet PID death percentages with previously published PID registries of other countries (Italy: black; Europe: gray; other countries: light gray). Parentheses next to each country name correspond to number of patients followed by year of analysis (number of patients; year of analysis)

Fig. 5

Minimal prevalence of PIDs in Italy and comparison with other countries. Comparison of minimal prevalence of PIDs in Italy calculated on alive patients with previously published data from other PID registries (Italy: black; Europe: gray; other countries: light gray). Parentheses next to each country name correspond to number of patients followed by year of analysis (number of patients; year of analysis)