The Reclassification of Patients With Previously Diagnosed Eosinophilic Granulomatosis With Polyangiitis Based on the 2022 ACR/EULAR Criteria for Antineutrophil Cytoplasmic Antibody–Associated Vasculitis

Objective The American College of Rheumatology (ACR) and the European Alliance of Associations for Rheumatology (EULAR) have proposed the 2022 classification criteria for eosinophilic granulomatosis with polyangiitis (EGPA). This study applied the 2022 ACR/EULAR criteria to Korean patients with previously diagnosed EGPA to investigate the concordance rate between the 2022 ACR/EULAR criteria and the old criteria for EGPA. Methods In total, 51 patients with EGPA who met the 1990 ACR criteria, the 2007 European Medicines Agency algorithm, and the 2012 Chapel Hill Consensus Conference definitions were reclassified based on the 2022 ACR/EULAR criteria. Results Of 51 patients, 44 (86.3%) were reclassified as having EGPA according to the 2022 ACR/EULAR criteria. Among the 7 patients who failed to meet the 2022 ACR/EULAR criteria, 3 patients were reclassified as having microscopic polyangiitis (MPA) and 1 was reclassified as having granulomatosis with polyangiitis (GPA) based on the 2022 ACR/EULAR criteria; as well, 3 patients were reclassified as having unclassifiable vasculitis. Moreover, 6 patients who met the 2022 ACR/EULAR criteria for EGPA simultaneously met the criteria for MPA based on the 2022 ACR/EULAR criteria for MPA, and 1 who met the criteria for EGPA simultaneously met the criteria for GPA based on the 2022 ACR/EULAR criteria for GPA. Conclusion The concordance rate between the 2022 ACR/EULAR criteria for EGPA and the old criteria was 86.3%. The most important factor in the failure to reclassify patients as having EGPA was the exclusion of nonfixed pulmonary infiltrates in the 1990 ACR criteria for EGPA. We cautiously suggest reconsidering nonfixed pulmonary infiltrates in cases reclassified as unclassifiable vasculitis. Further, additional classification strategies are needed for patients who simultaneously satisfy both antineutrophil cytoplasmic antibody–associated vasculitis subtypes.