What are the advantages of the latest Antiphospholipid Syndrome (APS) classification criteria compared to the previous criteria?

Advantages of the Latest APS Classification Criteria Compared to Previous Classification

The 2023 ACR/EULAR APS classification criteria offer significantly higher specificity (99% vs 86%) compared to the previous revised Sapporo criteria, providing a stronger foundation for APS research while maintaining essential laboratory parameters. 1

Key Improvements in the New Classification Criteria

Enhanced Specificity and Structure

• The new criteria feature a hierarchically clustered, weighted, and risk-stratified approach that better reflects current understanding of APS 1
• Criteria are organized into 6 clinical domains (macrovascular venous thromboembolism, macrovascular arterial thrombosis, microvascular, obstetric, cardiac valve, and hematologic) and 2 laboratory domains 2
• Point-based scoring system (1-7 points per criterion) requires at least 3 points from both clinical and laboratory domains for classification 1

Laboratory Criteria Refinements

• Maintains the cornerstone laboratory parameters: lupus anticoagulant (LA), anticardiolipin antibodies (aCL), and anti-β2-glycoprotein I antibodies (aβ2GPI) 3
• Establishes standardized moderate (>40 Units) and high (>80 Units) titer thresholds for antibody levels, abandoning the previous 99th percentile cutoff approach 3
• Continues to restrict aCL and aβ2GPI measurement to enzyme-linked immunosorbent assays (ELISAs) for consistency 3

Clinical Application Clarity

• Provides clearer distinction between classification criteria (for research) and diagnostic assessment (for clinical care) 3
• Emphasizes that classification criteria are strict and meant for participant inclusion in studies to ensure homogeneous populations 3
• Acknowledges that laboratory detection for APS diagnosis in daily practice should be broader to optimize patient management 3

Important Considerations for Implementation

Risk Stratification

• The "triple positivity" pattern (LA, aCL, and aβ2GPI) continues to identify patients with higher thrombotic risk 4
• Single LA positivity carries lower thrombotic risk than triple positivity, an important distinction maintained in the new criteria 4

Laboratory Testing Recommendations

• LA testing should be performed using two phospholipid-dependent coagulation tests (dRVVT and LA-sensitive APTT) 4
• Using only one test for LA increases risk of underdiagnosis by up to 31% 4
• LA testing should be avoided during anticoagulant therapy, especially with vitamin K antagonists 4

Potential Limitations

• The higher specificity (99%) comes with a trade-off of slightly reduced sensitivity (84% vs 99% in previous criteria) 1
• The criteria maintain restriction to ELISA methods for aCL and aβ2GPI despite increasing use of non-ELISA methods in clinical practice 3
• Does not fully address the role of non-criteria antiphospholipid antibodies that may have diagnostic value in seronegative APS 5

Clinical Implications

• The new criteria provide a more accurate framework for patient selection in clinical trials and observational studies
• Improved specificity helps reduce misclassification of patients without true APS
• Clear separation between classification and diagnosis reminds clinicians that patients may require treatment for APS even if they don't fully meet classification criteria 3
• Laboratory and clinical interaction remains essential for accurate diagnosis and management 4

By providing more structured, weighted criteria with improved specificity, the 2023 ACR/EULAR classification criteria represent a significant advancement in standardizing APS research while acknowledging the complexity of clinical diagnosis.