What is Antiphospholipid Syndrome (APS)?

From the Guidelines

Antiphospholipid syndrome (APS) should be diagnosed and managed based on the latest guidance from the ISTH-SSC LA/aPL Subcommittee, which emphasizes the importance of accurate detection and interpretation of antiphospholipid antibodies (aPL) for diagnosis and treatment. The diagnosis of APS is dependent on the detection of aPL, including lupus anticoagulant, anticardiolipin, and anti-β2GPI antibodies, with a focus on persistent positivity and moderate to high titers [ 1 ].

Key Considerations for Diagnosis

• The 2023 American College of Rheumatology (ACR)/European Alliance of Associations for Rheumatology (EULAR) classification criteria for APS emphasize the role of persistent lupus anticoagulant, anticardiolipin, and anti-β2GPI in the diagnosis [ 1 ].
• The distinction between classification criteria and routine clinical care is crucial, with classification criteria aiming to enhance specificity and homogeneity for research purposes, while clinical diagnosis focuses on optimizing patient care [ 1 ].

Management Strategies

• Treatment typically involves anticoagulation therapy, with warfarin being a common choice, targeting an INR of 2.0-3.0 for most patients or 3.0-4.0 for those with recurrent thrombosis [ 2, 3 ].
• For pregnant women with APS, the standard regimen includes low-dose aspirin plus prophylactic low molecular weight heparin [ 2 ].
• Patients with APS who experience a thrombotic event should remain on lifelong anticoagulation, with considerations for adjusted-dose vitamin K antagonist (VKA) therapy over direct-acting oral anticoagulant (DOAC) therapy during the treatment phase [ 3 ].

Monitoring and Education

• Regular monitoring of blood counts and coagulation parameters is essential for patients on anticoagulation therapy.
• Patients should be educated about bleeding risks, medication interactions, and the importance of consistent INR monitoring if on warfarin.

From the Research

Definition and Characteristics of Antiphospholipid Syndrome

• Antiphospholipid syndrome (APS) is an acquired thrombo-inflammatory disorder characterized by thrombosis or pregnancy morbidity, in association with persistent antiphospholipid antibodies (aPL) 4.
• APS can be primary or associated with another autoimmune disease, such as systemic lupus erythematosus 5.
• The main manifestations of APS are recurrent vascular thromboses and pregnancy complications 6.

Diagnosis and Clinical Features

• Diagnosis of APS requires a persistently positive functional lupus anticoagulant (LA) assay and/or the presence of anti-b2GPI and/or anti-cardiolipin antibodies, together with clinical symptoms 6.
• Clinical features of APS include thrombocytopenia, Coombs-positive haemolytic anaemia, heart valve disease, renal microangiopathy, and neurologic disorders 6.
• Catastrophic APS (CAPS) is a rare and severe form of APS, characterized by excessive thrombosis at multiple sites, usually affecting small vessels and leading to multi-organ dysfunction and organ failure 6.

Treatment and Management

• Antithrombotic therapy is the mainstay of treatment for APS, and recommendations vary based on arterial, venous, or pregnancy complications 5.
• Warfarin or an alternative vitamin K antagonist (VKA) is the standard anticoagulant treatment for thrombotic APS, but direct oral anticoagulants (DOACs) may be a potential treatment option for low-risk patients 7.
• Accurate assessment of anticoagulation intensity is essential to optimize anticoagulant dosing and minimize the risk of recurrent thrombosis or bleeding 4, 8.
• Treatment of CAPS typically involves a combined therapeutic approach, including anticoagulation, glucocorticoids, plasma exchange, and/or intravenous immunoglobulin 6.

Monitoring and Prevention

• Monitoring of anticoagulation in APS patients is crucial to ensure optimal anticoagulant dosing and prevent recurrent thrombosis or bleeding 4, 8.
• Lupus anticoagulant can affect phospholipid-dependent coagulation monitoring tests, making it essential to use alternative tests to assess anticoagulation intensity 4, 8.
• Hydroxychloroquine is recommended as primary and secondary prophylaxis for patients with APS associated with systemic lupus erythematosus 5.