# Incidence and clinical features of ANCA-associated vasculitis before and during the COVID-19 pandemic: experience from a single-center in Northern Spain

## TL;DR

This study found a temporary increase in a type of vasculitis during the early years of the COVID-19 pandemic in Northern Spain.

## Contribution

The study reports a significant rise in ANCA-associated vasculitis cases during the pandemic and links it to recent SARS-CoV-2 infection or vaccination.

## Key findings

- AAV incidence increased from 22.4 to 37.9 cases per million between 2019 and 2021.
- About 40% of AAV cases during the pandemic were linked to recent SARS-CoV-2 infection or vaccination.
- MPO-ANCA remained the most common subtype despite a rise in PR3-ANCA cases.

## Abstract

A transient increase in anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) incidence was observed during the coronavirus disease 2019 (COVID-19) pandemic. This study aimed to assess new AAV diagnoses during the COVID-19 pandemic in a single-center cohort.

We conducted a retrospective observational study of patients newly diagnosed with AAV at a tertiary care university hospital in Northern Spain between January 2019 and December 2022. Cases were classified according to the 2022 American College of Rheumatology/European Alliance of Associations for Rheumatology (ACR/EULAR) criteria. Clinical and serologic data were collected, including antibody specificity for proteinase 3 (PR3-ANCA) and myeloperoxidase (MPO-ANCA), as well as the temporal relationship to SARS-CoV-2 infection or COVID-19 vaccination.

A significant increase in AAV incidence was observed during the pandemic, rising from 22.4 cases per million in 2019 to 37.9 cases per million in 2021 (p = 0.031). Approximately 40% of patients diagnosed during this period had a recent SARS-CoV-2 infection or had been vaccinated against COVID-19 in the preceding 3 months. By 2022, AAV incidence returned to pre-pandemic levels. Contrary to initial trends, demographic and clinical characteristics remained stable; no significant differences were observed in age, gender distribution, disease severity, or organ involvement between the pre-pandemic and pandemic periods. While a numerical increase in PR3-ANCA cases was noted during the pandemic, MPO-ANCA remained the predominant subtype.

The temporary but significant rise in AAV incidence suggests a possible temporal association with COVID-19 infection or vaccination. These findings underscore the need to conduct larger, multicentre studies to confirm these observations, investigate potential pathophysiological mechanisms, and improve clinical management approaches.