Antiphospholipid syndrome overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Feham Tariq, MD [2]
Overview
Antiphospholipid syndrome (APS or APLS) or antiphospholipid antibody syndrome is a disorder of coagulation, which can causes blood clots (thrombosis) in both arteries and veins, as well as pregnancy-related complications such as miscarriages, preterm deliveries, or severe preeclampsia. The syndrome occurs due to the autoimmune production of antibodies against phospholipid (aPL), a cell membrane substance. In particular, the disease is characterized by antibodies against cardiolipin (anti-cardiolipin antibodies) and β2 glycoprotein I.
The term "primary antiphospholipid syndrome" is used when APS occurs in the absence of any other related disease. APS is commonly seen in conjunction with other autoimmune diseases; the term "secondary antiphospholipid syndrome" is used when APS coexists with other diseases such as systemic lupus erythematosus (SLE). In rare cases, APS leads to rapid organ failure due to generalized thrombosis and a high risk of death; this is termed "catastrophic antiphospholipid syndrome".
Antiphospholipid syndrome is sometimes referred to as Hughes syndrome after the rheumatologist Dr. Graham R.V. Hughes (St. Thomas' Hospital, London, United Kingdom) who worked at the Louise Coote Lupus Unit at St Thomas' Hospital in London.
Historical Perspective
In the early 1980s, the term antiphospholipid syndrome was coined to describe a unique form of autoantibody-induced thrombophilia. In 1999, Sapporo classification criteria for APS was published. In 2006, the preliminary Sapporo criteria was revised with the inclusion of anti-β2 glycoprotein I (GPI) antibodies in the diagnostic criteria.
Classification
Antiphospholipid syndrome (APS) can be divided into primary and secondary APS.
Pathophysiology
Antiphospholipid syndrome (APS) is an autoimmune disease in which antiphospholipid antibodies (anti-cardiolipin antibodies and lupus anticoagulant) react against proteins that bind to anionic phospholipids on plasma membranes. This syndrome can be classified into primary (no underlying disease state) and secondary (in association with an underlying disease state) types. The underlying mechanism of APS mediated by the antibodies is mainly mediated via their affect on the coagulation cascade which subsequenlty leads to increased vascular tone of thrombosis. CAPS is a subclass of APS that results in development of a catastrophic illness characterized by progressive, severe arterial and venous thrombosis in multiple organs, often leading to death.
Differentiating Antiphospholipid syndrome from other Diseases
Antiphospholipid syndrome needs to be differentiated from Hemolytic uremic syndrome-Thrombotic thrombocytopenic purpura (HUS-TTP), Disseminated Intravascular Coagulation (DIC) and vasculitis among others.
Causes
Antiphospholipid syndrome can occur idiopathic or due to autoimmune diseases, certain drugs, infections and malignancies.
Differentiating Antiphospholipid syndrome from other Diseases
Epidemiology and Demographics
The incidence of antiphospholipid syndrome (APS) is approximately 5 cases per 100,000 persons per year. The prevalence of APS is approximately 40-50 cases per 100,000 persons worldwide. APS due to systemic lupus erythematosus (SLE) is more commonly seen in the African American and Hispanic population. Middle aged women are more commonly affected by APS than males.
Risk Factors
Natural History, Complications and Prognosis
Diagnosis
Diagnostic Criteria
The diagnosis of Antiphospholipid syndrome is made in case of a clinical event (vascular thrombosis or pregnancy event) and repeated positive tests of aPL performed 12 weeks apart (repeat aPL testing is necessary due to the naturally occurring presence of transient low levels of aPL following infections).
History and Symptoms
Physical Examination
The presence of antiphospholipid antibodies (aPL) in the absence of blood clots or pregnancy-related complications does not indicate APS (see below for the diagnosis of APS).
Antiphosphilipid syndrome can cause (arterial/venous) blood clots (in any organ system) or pregnancy-related complications (especially miscarriage in the second or third trimester). In APS patients, the most common venous event is deep vein thrombosis of the lower extremities (blood clot of the deep veins of the legs) and the most common arterial event is stroke.
Laboratory Findings
Antiphospholipid syndrome is tested for in the laboratory using both liquid phase coagulation assays (lupus anticoagulant) and solid phase ELISA assays (anti-cardiolipin antibodies).
Electrocardiogram
Chest X Ray
CT Scan
Echocardiography or Ultrasound
Other Imaging Findings
Treatment
Medical Therapy
The cornerstone of therapy for symptomatic antiphospholipid syndrome hinges on platelet inhibition with or without anticoagulation. Platelet inhibition is often achieved with aspirin, while warfarin and heparin are the mainstays of anticoagulation. Generally there is no indication for primary prophylaxis. Immunosuppression, the use of intravenous immunoglobulin, and plasmapheresis have also been used with modest success.