ANCA-Related Vasculitis Incidence and Features before and during the Covid-19 pandemic in Los Angeles, Biobio Province Chile: An observational retrospective analysis

Daniel Enos Brito^1*Mariel Hernandez¹Gonzalo P Méndez²Lysis Caceres³Ignacia Bravo³Josefina Jobet³Simon Castro³Lorena Cornejo¹Catalina Vega¹Andres Salazar¹

• ¹Victor Rios Ruiz Complex, Los Ángeles, Chile
• ²Laboratorio Inmunocel, Santiago, Chile
• ³Universidad San Sebastian, Concepción, Chile

Introduction: Renal vasculitis is a rare disease whose incidence increased markedly during the COVID-19 pandemic in our center. The aim of this study is to compare the incidence and their clinical and histopathological characteristics of ANCA-associated vasculitis patients before and during the COVID-19 pandemic. Methods: A single-center observational retrospective analysis of 61 ANCA-associated vasculitis patients who were divided into two groups according to date of diagnosis, pre-pandemic from 2008-2020 (n=37) and during the pandemic 2020 to middle 2022 (n=24). Annual incidence rate was compared along and characteristics such as age, gender, BVAS score, renal clinic, organs involvement and ANCA serotype. Biopsy findings such as optical microscopy glomerular characteristics, crescents, interstitium, immunofluorescence and electron microscopy findings were analysed. Mortality and renal replacement therapy needs were also compared. Results: Annual incidence rate was higher in the pandemic group compared to pre-pandemic group being 9.6 cases per year versus 3.1 cases per year (IRR=3.11 95%CI 1.86 to 5.20). No mayor differences between groups were found among clinical characteristics except a greater hemoptysis frequency in pandemic. Significant differences in immunofluorescence and electronic microscopy were observed, with a higher IgG deposit and C3 in the pandemic group (37.5% vs 8.1%, p=0.0064; 43.5% vs 10.8%, p=0.009 respectively) whereas pauci immune was higher in the pre pandemic group (81.1% vs 54.1%, p=0.016). Mortality and need of renal replacement therapy were significant higher in the pandemic group (Incidence Rate Ratio of 3.56, CI 95% 1.27-9.98 and 4.24, CI 95% 2.08-8.65 respectively) Conclusion: The incidence of ANCA vasculitis increased during the COVID-19 pandemic and was associated in this group with higher rates of IgG deposit and C3 in the immunofluorescence, and associated with higher rates of deaths and dialysis compared with the pre-pandemic group.