What are the diagnostic criteria for Catastrophic Antiphospholipid Syndrome (APS)?

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Dainyal Siddiqui, MD

Internal Medicine

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Manuel Jimenez, MD

Cardiology

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Franz Pierre-Louis, MD

Infectious Disease

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Last updated: February 25, 2025 • View editorial policy

From the Guidelines

The diagnostic criteria for Catastrophic Antiphospholipid Syndrome (APS) involve the presence of antiphospholipid antibodies (aPL), including lupus anticoagulant (LA), anticardiolipin antibodies (aCL), and anti-beta2 glycoprotein I antibodies (aβ2GPI), with a focus on moderate and high titer thresholds defined as 40 and 80 Units, respectively, as per the 2023 American College of Rheumatology (ACR)/European Alliance of Associations for Rheumatology (EULAR) APS classification criteria 1, 2.

Key Diagnostic Considerations

  • The diagnosis of APS is dependent on the accurate detection and interpretation of aPL, which can induce thrombosis, pregnancy morbidity, and other autoimmune and inflammatory manifestations 1.
  • The 2023 ACR/EULAR APS classification criteria emphasize the importance of LA, aCL, and aβ2GPI in the laboratory diagnosis of APS, with a focus on ELISA measurements and moderate and high titer thresholds 2.
  • The distinction between classification criteria and assessment of aPL in clinical care is crucial, as classification criteria are strict and meant for research purposes, while laboratory detection for APS diagnosis in daily practice is broader and aimed at optimizing patient management 2.

Laboratory Testing Recommendations

  • Concurrent testing for LA, aCL IgG and IgM, and aβ2GPI IgG and IgM is recommended, along with measurement of LA in citrated plasma according to the ISTH-SSC recommendations 3.
  • The use of alternative approaches, such as aPS/PT and aDI, may be considered in specific situations, such as when LA testing is unreliable or uncertain 3.
  • Interpretation of results should be based on local cutoff values and clinical context, with a focus on the aPL profile and the presence of triple or double positivity 3.

Clinical Implications

  • The diagnosis of Catastrophic APS requires a comprehensive approach, taking into account the clinical presentation, laboratory results, and medical history of the patient 1, 2.
  • The management of APS involves anticoagulation therapy, with a focus on preventing thrombotic events and improving patient outcomes 1, 2.
  • The recognition of Catastrophic APS is critical, as it is associated with high morbidity and mortality, and requires prompt and aggressive treatment to prevent organ damage and improve survival 1, 2.

From the Research

Diagnostic Criteria for Catastrophic Antiphospholipid Syndrome (APS)

The diagnostic criteria for Catastrophic Antiphospholipid Syndrome (APS) include:

  • Clinical evidence of multiple organ involvement developed over a short period of time 4, 5, 6, 7
  • Histopathologic evidence of small and large vessel occlusion 4, 7

  • Laboratory confirmation of the presence of antiphospholipid antibodies, usually in high titer 4, 5, 6, 7

    Clinical and Laboratory Criteria

    A diagnosis of APS requires the presence of at least one clinical and one laboratory criteria, including:

  • Detection of aCL IgG or IgM antibodies 4
  • Presence of lupus anticoagulant on two or more consecutive occasions 6 weeks apart 4
  • Previous APS diagnosis and/or persistent clinically significant aPL positivity is of great importance for the CAPS diagnosis 6

Definite and Probable CAPS

Definite and probable CAPS have been defined based on the preliminary classification criteria, however, in a real-world setting, aPL-positive patients with multiple organ thromboses and/or thrombotic microangiopathies exist who do not fulfill these criteria 6

Diagnostic Challenges

The diagnosis of CAPS can be challenging, and a high degree of clinical awareness is required, as almost half of the patients who develop CAPS do not have a history of aPL positivity 6

References

4
Research

Catastrophic antiphospholipid antibody syndrome.

Pediatric nephrology (Berlin, Germany), 2005

6
Research

Catastrophic antiphospholipid syndrome: how to diagnose a rare but highly fatal disease.

Therapeutic advances in musculoskeletal disease, 2013

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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