Insights into the 2023 ACR/EULAR Antiphospholipid Syndrome Classification Criteria: findings from a cohort of 205 patients with primary APS

• Published in: Rheumatology (Oxford, England) England), 2024-12
• Main Authors: Zen, Margherita, Tonello, Marta, Carta, Francesco, Calligaro, Antonia, Favaro, Maria, Del Ross, Teresa, Hulej, Greta, Rahmè, Zahra, Ruffatti, Amelia, Doria, Andrea
• Format: Article
• Language: English
• ISSN: 1462-0332; 1462-0332
• DOI: 10.1093/rheumatology/keae665

The 2023 ACR/EULAR antiphospholipid syndrome (APS) classification criteria distinguish between anticardiolipin (aCL) or anti-β2-glycoprotein I (aβ2GPI) IgG vs IgM isotypes, having isolate IgM positivity a low weight, insufficient for APS classification, and define aCL and aβ2GPI thresholds based on fixed cut-off values. We aimed to assess the performance of the 2023 ACR/EULAR criteria in a cohort of primary vascular APS patients (PAPS), previously classified according to the Sydney criteria. Additionally, we evaluated the risk of thrombotic recurrence in patients re-classified or not according to the new criteria. PAPS patients meeting the Sydney criteria with previous vascular manifestations followed between 1992 and 2023 were re-evaluated to identify cases that would not be classified as PAPS based on the 2023 ACR/EULAR criteria. Our cohort included 205 PAPS patients: 171 met the ACR/EULAR classification criteria, 34 (16.6%) did not due to insufficient score in the laboratory domain caused by isolate IgM positivity (23 patients) or aPL positivity at a titer > 99th percentile but