The Performance of 2023 American College of Rheumatology (ACR) / European Alliance of Associations for Rheumatology (EULAR) Antiphospholipid Syndrome Classification Criteria in a Real-World Rheumatology Department.

Background: Antiphospholipid Syndrome (APS) is one of the most common acquired causes of hypercoagulability. The 2023 American College of Rheumatology (ACR) / European Alliance of Associations for Rheumatology (EULAR) APS Classification Criteria were specified as new APS classification criteria with high specificity for use in observational studies and research. The primary objective of this study was to evaluate the performance of the 2023 ACR/EULAR APS classification criteria in a real-world rheumatology department. Methods: This is a retrospective, single-center study evaluating the sensitivity and specificity of the 2006 revised Sapporo and 2023 ACR/EULAR APS classification criteria in patients diagnosed with APS through clinical evaluation. A total of 184 patients, 103 of whom were diagnosed with APS, were included in the study. Results: The 2023 ACR/EULAR APS classification criteria demonstrate higher specificity 98.8% (95% CI 93.3-99.8) and positive predictive value (PPV) 98.7% (95% CI 93.2-99.8). The revised Sapporo criteria exhibit higher sensitivity 90.3% (95% CI 83-96.6), negative predictive value (NPV) 88.1% (95% CI 79.4-93.4), and accuracy 90.8% (95% CI 85.7-94.1). When the diagnosis of APS was accepted according to the revised Sapporo criteria, the sensitivity of the 2023 ACR/EULAR APS classification criteria was 77% (95% CI 67.8-84.2), specificity 97.6% (95% CI 91.7-99.3), PPV 97.5% (95% CI 69.3-84.9) and NPV 78.1% (95% CI 69.3-84.9). Conclusion: The 2023 ACR/EULAR APS classification criteria have low sensitivity and high specificity compared to the revised Sapporo APS classification criteria. The increase in specificity is due to risk assessment in thromboses and strict obstetric and laboratory criteria.