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Abstract: TH-PO610

Impact of Reclassification by the 2022 ACR/EULAR Classification Criteria on the ANCA-Associated Vasculitis Study Population

Session Information

Category: Glomerular Diseases

  • 1402 Glomerular Diseases: Clinical, Outcomes, and Trials

Authors

  • van Leeuwen, Jolijn R., Leids Universitair Medisch Centrum, Leiden, Zuid-Holland, Netherlands
  • Hafemann, Sophia Lynn, Leids Universitair Medisch Centrum, Leiden, Zuid-Holland, Netherlands
  • Rabelink, Ton J., Leids Universitair Medisch Centrum, Leiden, Zuid-Holland, Netherlands
  • Teng, Yoe Kie Onno, Leids Universitair Medisch Centrum, Leiden, Zuid-Holland, Netherlands
Background

In 2022 the American College of Rheumatology (ACR) and European Alliance of Associations for Rheumatology (EULAR) presented new classification criteria for the three subsets of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV): granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA) and Eosinophilic Granulomatosis with Polyangiitis (EGPA). Our aim was to assess the impact of the new 2022 ACR/EULAR classification criteria on future GPA, MPA and EGPA studies.

Methods

An established, single center cohort of patients with a clinical AAV diagnosis in a tertiary academic hospital was used as source population. Clinical diagnosis and disease characteristics at time of diagnosis were collected by manual review and matched to the novel 2022 ACR/EULAR classification criteria for GPA, MPA or EGPA. Patients with an unspecified AAV diagnosis and patients with insufficient clinical data for the time of diagnosis were excluded.

Results

We included 183 GPA, 54 MPA and 27 EGPA patients. In total 32/264 (12%) patients were reclassified. 22/183 (12%) clinical GPA patients were reclassified: 11 (6%) as MPA and 11 (6%) were unclassified. 3/54 (9%) MPA patients were reclassified: 1 (2%) as GPA and 2 (4%) were unclassified. 7/27 (25%) EGPA patients were reclassified: 3 (11%) as GPA and 4 (15%) patients were unclassified. One clinical GPA patient could be classified as both GPA and MPA.
After reclassification, PR3+ patients remain predominantly GPA (from 97 to 99%), MPO+ patients are more often considered MPA (from 64% to 75%) and ANCA- patients can often not be classified (29%). Focusing on risk factors for relapse, an often used endpoint in clinical trials, we identified an enrichment of PR3 positivity in GPA patients (+12%) and of pulmonary involvement in MPA patients (+10%) after reclassification.

Conclusion

With 12% reclassification the 2022 ACR/EULAR classification criteria will impact inclusion in future studies. Reclassification is often based on ANCA serology and impacts the distribution of typical risk factors for disease relapse in MPA and GPA subgroups.