Diagnosis and management of C3 glomerulopathy in Italy: a Delphi consensus

C3 glomerulopathy (C3G) includes dense deposit disease and C3 glomerulonephritis, both of which can be associated with membranoproliferative glomerulonephritis. The prevalence and true burden of C3G in Italy is difficult to estimate due to the rarity of the disease and a lack of epidemiological and patient-reported data. Moreover, diagnosis of C3G is challenging and complex due to its nonspecific clinical characteristics, a continually evolving disease classification, and the need for careful interpretation of immunofluorescence, light microscopy and electron microscopy kidney biopsy findings. Here, we provide a narrative review of the relevant literature, along with 38 consensus statements specific to the Italian context that were developed by an eight-member scientific advisory board, and voted on by a 42-member expert panel, with consensus reached using Delphi methodology. We outline the patient journey and management of C3G in Italy, highlighting ways of improving the current pathway, and suggesting steps to improve our understanding of the disease. The consensus statements cover: epidemiology of C3G in Italy; classification of C3G; histology and diagnostic procedures; management of patient symptoms; the patient journey in C3G in terms of diagnosis, treatment and follow-up; and disease burden and quality of life. Two rounds of voting were conducted, and consensus (at least 66.6% of panelists voting agree/strongly agree on a 4-point Likert scale) was reached for all statements. These consensus statements, while specific to the Italian context, are broadly applicable globally and provide an overview of this rare disease as well as the necessary diagnostic steps.