Background

Definition

• Antiphospholipid syndrome (APS) is a systemic autoimmune disorder with a wide range of vascular and obstetric manifestations associated with thrombotic and inflammatory mechanisms orchestrated by antiphospholipid (aPL) antibodies.
• Also known as Hughes syndrome
• Commonly presents with venous thromboembolism, recurrent early miscarriages and late pregnancy losses.
• Rarely a life threatening form of multiorgan thrombosis known as catastrophic APS can occur.
• APS occurs either as a primary condition or in the setting of an underlying disease, usually systemic lupus erythematosus (SLE).
• Thrombophilias include disorders due to:
  • deficiency of antithrombin or proteins C or S
  • the presence of activated protein C resistance (eg factor V Leiden gene mutation)
  • the prothrombin gene mutation (20210A)
  • antiphospholipid antibodies

Epidemiology

• In patients without known autoimmune disease, aPL were present in approximately 9% of patients with pregnancy losses, 14% with stroke, 11% with myocardial infarction (MI), and 10% with deep vein thrombosis (DVT).
• In the United States, estimates suggest aPL are associated with approximately 50,000 pregnancy losses, 110,000 strokes, 100,000 MIs, and 30,000 DVTs annually

Classification

Can be classified based on presentation

• Thrombotic APS — diagnosed based on venous and/or arterial thrombosis and persistent laboratory criteria for aPL.
• Obstetric APS - diagnosed with APS based on certain adverse pregnancy outcomes (eg, fetal death after 10 weeks gestation, premature birth due to severe preeclampsia or placental insufficiency, or multiple embryonic losses [before 10 weeks gestation]) and persistent laboratory criteria for aPL.
• Catastrophic APS — thrombotic complications involving multi organ simultaneously or over a short period of time.
• Risk of APS based on antiphospholipid antibodies (aPL)
  • anticardiolipin antibody (aCL)
  • anti-beta2 glycoprotein I (anti-beta2GPI) antibody
  • lupus anticoagulant
  • others: IgA aCL, antibodies directed against prothrombin, phosphatidylserine, or phosphatidylinositol [not routinely obtained because lack of standardised testing or uncertain about their clinical significance]