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Li Wenchao; Chen Ruifan; Chen Wei; Huang Fengxian; Xia Xi: Clinicopathological Features and Outcomes of IgA Nephropathy with Serum Antineutrophil Cytoplasmic Autoantibody Positivity. American Journal of Nephrology DOI 10.1159/000533982
IgA nephropathy (IgAN) is a common glomerular disease that is not infrequently accompanied by superimposed crescentic glomerulonephritis (GN) of varying severity. Extensive crescentic disease (>50% glomerular involvement) with rapidly progressive GN is rather uncommon (<5% in most series). The role of testing for ANCA in patients with IgAN is largely unknown.
Li and co-workers retrospectively studied 2,864 patients with biopsy-proven IgAN at a single center in China diagnosed between 2007 and 2019. 85% of these cases were primarily tested for anti-myeloperoxidase antibody (about 3% were positive), but only about 50% were tested for ANCA. Only 4 cases had extensive crescentic disease. The clinical/pathologic manifestations were similar in ANCA+ and ANCA– IgAN, except that ANCA+ IgAN had more ANA+, more extra-renal manifestations, and less interstitial inflammation. The rate of ESKD after a follow-up period of 40–48 months was the same in ANCA+ and ANCA– IgAN. All-cause mortality was low (about 1%) in both groups. Discrepancies in the results of ANCA testing by indirect immunofluorescence and chemiluminescent ANCA assays were observed. This was an exclusively Chinese study, so the results may not be applicable to other geographical regions.
In sum, this retrospective single-center study seems to suggest that ANCA+ does not necessarily confer an adverse prognosis, except possibly in males with concomitant ANA+ (a hypothesis requiring further study). It raises questions as to whether a therapeutic approach to lower ANCA levels (e.g., Rituximab, Cyclophosphamide, plasma exchange) would have any beneficial effects, but the design of the study cannot answer these questions.
