Retrospective Analysis of a Large Brazilian Center on Systemic Vasculitis and Evaluation of C3 Levels Behavior

Le résumé fourni par la source

Background: Systemic small vessel vasculitis are characterized by necrotizing inflammation with little or no deposition of immune complexes. Activation of the alternative complement pathway is part of the disease's pathophysiological mechanism. This study aims to identify the profile of these vasculitis in a large Brazilian center and the behavior of complement levels over time. Methods: Patients diagnosed with vasculitis between February 2012 and September 2023 were included. The evaluated data included age, sex, creatinine, estimated glomerular filtration rate by CKD-EPI, proteinuria, hematuria, ANCA positivity, serum C3 levels at diagnosis, and the average C3 levels after 6-12 months of follow-up. Results: 48 patients were diagnosed with vasculitis through biopsies during this period, with 60% being women. The median age was 60 years (14-83), serum creatinine 3.7 mg/dL (SD ± 1.7), eGFR 17 mL/min (7-79), proteinuria 1.43g (0.05-8.4), 96% had hematuria, admissional C3 was 107 (41-174), 38% c-ANCA positive and 43% p-ANCA positive. Chi-square test was conducted to assess the association between serum C3 and the intensity of C3 in renal biopsy (p 0.56). Tukey and Bonferroni tests were performed to evaluate C3 variation during treatment, no statistically significant difference was found (p 0.29). Conclusion: We couldn't identify changes in the behavior of C3 levels in the present study. The local activation of the alternative complement pathway is well established in ANCA-associated vasculitis, however this could be difficult to identify in the usual laboratory assays. Therefore, identifying patterns of mild changes on systemic C3 levels in patients with vasculitis might be feasible utilizing larger samples.

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