Expert consensus identifies 60 to 90 incident C3G cases annually in Italy with 94% agreementExperts Reach Consensus on C3 Glomerulopathy Diagnosis and Treatment

BackgroundC3 glomerulopathy (C3G) is a chronic kidney disease previously included within the broader spectrum of membranoproliferative glomerulonephritis. Information on various aspects of C3G, including epidemiology, management, and patient needs, is extremely scarce at the international and particularly at a national level.MethodsBetween April 2024 and February 2025, we conducted an online iterative modified Delphi study involving Italian nephrologists with expertise in C3G. The Delphi study was performed according to the best practices for defining consensus and was reported following the ACcurate COnsensus Reporting Document (ACCORD) guidelines. Five main areas of investigation of C3G were explored, i.e., epidemiology, patient characteristics, disease outcomes, treatment, and other mixed aspects.ResultsOf the 23 invited clinicians, 2 (8.7%) did not reply and 4 (17.4%) did not satisfy the inclusion criteria defined by the Steering Committee. Thus, the voting panel included 17 Italian experts. Two iterations were required to complete the Delphi study. All 17 panellists participating to the first iteration completed the second Delphi round. Agreement was achieved on an estimated number of 60–90 incident patient per year (94% agreement) and about 2700 prevalent cases of C3G (82% agreement) in Italy. The stabilization of eGFR and an improvement in proteinuria emerged as key disease and treatment outcomes. All experts agreed that the availability of specific and effective treatments and rapid and correct disease diagnosis are currently the most important unmet needs related to C3G.ConclusionsThis investigation provided relevant information for improving our knowledge of C3G, stimulate discussion and enhance research on this ultra-rare disease in Italy.