CO097 | IMPACT OF THE 2023 ACR/EULAR ANTIPHOSPHOLIPID SYNDROME CRITERIA IN 1200 WOMEN WITH PRIOR OBSTETRIC ANTIPHOSPHOLIPID SYNDROME
Abstract
Background and aims. The 2023 ACR/EULAR classification criteria for antiphospholipid syndrome (APS) were developed to improve specificity, but concerns have emerged regarding their sensitivity, particularly in obstetric APS (OAPS). This study aimed to assess the impact of the new criteria on a large, well-characterized cohort of women previously classified with OAPS according to the Sydney criteria and to explore potential clinical implications of reclassification. Methods. We analyzed 1,200 women included in the EUROAPS registry who fulfilled the 2006 Sydney classification criteria for obstetric APS. These cases were re-evaluated using the 2023 ACR/EULAR criteria, focusing on obstetric clinical manifestations (domain 4) and laboratory features (domain 8). The cohort included patients from 30 tertiary centers across Europe and Argentina. Descriptive analyses were performed to determine the proportion of patients remaining classifiable under the new framework and to identify the main factors driving exclusion. Results. Application of the 2023 ACR/EULAR criteria led to a substantial reduction in classifiable cases. Based on clinical criteria alone, 68% of women were excluded, primarily due to the lower weighting of recurrent pregnancy loss and fetal death. Additional exclusions occurred when applying laboratory constraints, including reduced consideration of isolated IgM positivity and the introduction of fixed antibody thresholds. Overall, only 256 out of 1,200 women (21.3%) remained classifiable as OAPS. The main drivers of reclassification were the stringent scoring system in the obstetric domain, the non-cumulative nature of clinical items, and restrictive laboratory definitions. Conclusions. In this large multicenter cohort, the 2023 ACR/EULAR criteria markedly reduced the number of women classified with obstetric APS compared with the Sydney criteria. While increased specificity may benefit research homogeneity, the significant loss of sensitivity raises concerns about under-recognition of clinically relevant disease. These findings highlight the need for careful clinical judgement and further prospective studies to refine classification strategies and ensure that patients at risk are not overlooked.
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BibTeX
@article{hoxha2026co097,
title = {{CO097 | IMPACT OF THE 2023 ACR/EULAR ANTIPHOSPHOLIPID SYNDROME CRITERIA IN 1200 WOMEN WITH PRIOR OBSTETRIC ANTIPHOSPHOLIPID SYNDROME}},
author = {Ariela Hoxha},
journal = {Bleeding, Thrombosis and Vascular Biology},
year = {2026},
month = oct,
url = {https://www.btvb.org/btvb/article/view/799},
note = {CC BY-NC},
}
RIS
TY - JOUR
TI - CO097 | IMPACT OF THE 2023 ACR/EULAR ANTIPHOSPHOLIPID SYNDROME CRITERIA IN 1200 WOMEN WITH PRIOR OBSTETRIC ANTIPHOSPHOLIPID SYNDROME
AU - Ariela Hoxha
PY - 2026
DA - 2026/10/26
JO - Bleeding, Thrombosis and Vascular Biology
UR - https://www.btvb.org/btvb/article/view/799
AB - Background and aims. The 2023 ACR/EULAR classification criteria for antiphospholipid syndrome (APS) were developed to improve specificity, but concerns have emerged regarding their sensitivity, particularly in obstetric APS (OAPS). This study aimed to assess the impact of the new criteria on a large, well-characterized cohort of women previously classified with OAPS according to the Sydney criteria and to explore potential clinical implications of reclassification. Methods. We analyzed 1,200 women included in the EUROAPS registry who fulfilled the 2006 Sydney classification criteria for obstetric APS. These cases were re-evaluated using the 2023 ACR/EULAR criteria, focusing on obstetric clinical manifestations (domain 4) and laboratory features (domain 8). The cohort included patients from 30 tertiary centers across Europe and Argentina. Descriptive analyses were performed to determine the proportion of patients remaining classifiable under the new framework and to identify the main factors driving exclusion. Results. Application of the 2023 ACR/EULAR criteria led to a substantial reduction in classifiable cases. Based on clinical criteria alone, 68% of women were excluded, primarily due to the lower weighting of recurrent pregnancy loss and fetal death. Additional exclusions occurred when applying laboratory constraints, including reduced consideration of isolated IgM positivity and the introduction of fixed antibody thresholds. Overall, only 256 out of 1,200 women (21.3%) remained classifiable as OAPS. The main drivers of reclassification were the stringent scoring system in the obstetric domain, the non-cumulative nature of clinical items, and restrictive laboratory definitions. Conclusions. In this large multicenter cohort, the 2023 ACR/EULAR criteria markedly reduced the number of women classified with obstetric APS compared with the Sydney criteria. While increased specificity may benefit research homogeneity, the significant loss of sensitivity raises concerns about under-recognition of clinically relevant disease. These findings highlight the need for careful clinical judgement and further prospective studies to refine classification strategies and ensure that patients at risk are not overlooked.
SN - 2785-5309
ER -