Antiphospholipid syndrome (APS): causes, treatment and prevention
Antiphospholipid syndrome is an immune disorder in which abnormal antibodies are linked to abnormal blood clots in veins and arteries. It mostly affects the legs, but clots may also form in the kidneys, lungs and other organs. Antiphospholipid syndrome (APS) is also known as Antiphospholipid Antibody Syndrome, Hughes syndrome, or sticky blood.
Antiphospholipid syndrome was described in full in the 1980s, by Nigel Harris and Aziz Gharavi. They published the first papers in 1983. The syndrome was referred to as “Hughes syndrome” among colleagues after the rheumatologist Graham R.V. Hughes (St. Thomas’ Hospital, London, UK), who brought together the team.
The actual frequency of APS in the general population is unknown. One to 5% of healthy individuals have aPL antibodies. It is estimated that the incidence of APS is approximately 5 cases per 100,000 persons per year, and the prevalence is approximately 40-50 cases per 100, 000 persons. aCL antibodies tend to be found more frequently in elderly persons; thus, positive titer results should be interpreted with caution in this population. aPL antibodies are found in approximately 30-40% of patients with SLE, but only about 10% have APS. Approximately half of APS cases are not associated with another rheumatic disease. In a study of 100 patients with confirmed venous thrombosis and no history of SLE, aCL antibodies were found in 24% and LA in 4%. aPL syndrome is the cause of 14% of all strokes, 11% of myocardial infarctions, 10% of deep vein thromboses, 6% of pregnancy morbidity, and 9% of pregnancy losses.
International frequency is probably similar to US frequency.
APS is divided into two types – primary and secondary:
Primary APS: More than half of people with APS have primary APS. This is APS on its own, and not associated with any other disease.
Secondary APS: This is APS that is associated with another disease, such as a rheumatic disease that affects the bones, joints or soft tissues. An example is systemic lupus erythematosus (SLE, or lupus). SLE seems to be the disease most commonly associated with APS. Many of the rheumatic diseases (including SLE) that are associated with APS are autoimmune diseases. This means that the immune system (which normally protects the body from infections) mistakenly attacks itself. This can cause symptoms and may damage the affected parts of the body.
Antiphospholipid syndrome affects women much more than it does men. Other risk factors include:
- Having an autoimmune condition, such as systemic lupus erythematosus or Sjogren’s syndrome
- Having certain infections, such as syphilis, HIV/AIDS, hepatitis C or Lyme disease
- Taking certain medications, such as hydralazine for high blood pressure, the heart rhythm-regulating medication quinidine, the anti-seizure medication phenytoin (Dilantin) and the antibiotic amoxicillin
- Having a family member with antiphospholipid syndrome
The role of phospholipids
In antiphospholipid syndrome, your blood clots abnormally because your body mistakenly produces antibodies that attack phospholipids, a type of fat that plays a key role in clotting. Antibodies are proteins that normally protect the body against invaders, such as viruses and bacteria.
Antiphospholipid syndrome can be caused by an underlying condition, such as an autoimmune disorder, infection or certain medications, or you can develop the syndrome without an underlying cause.
Signs and symptoms of antiphospholipid syndrome can include:
- Blood clots in your legs (DVT). The clots can travel to your lungs (pulmonary embolism).
- Repeated miscarriages or stillbirths. Other complications of pregnancy include premature delivery and high blood pressure during pregnancy (preeclampsia).
- A stroke can occur in a young person who has antiphospholipid syndrome but no known risk factors for cardiovascular diseases.
- Transitory ischemic attack (TIA). Similar to a stroke, a TIA usually lasts only a few minutes and causes no permanent damage.
- Some people develop a red rash with a lacy, net-like pattern (livedo reticularis).
Diagnosis and test
- A doctor will test for antiphospholipid syndrome if the patient has at least one episode of thrombosis or a pregnancy loss.
- A blood test will show whether a person has abnormal antibodies.
- Sometimes harmless antiphospholipid antibodies may develop for limited periods, because of an infection or some medication, so a second test will be needed to confirm the result.
- If blood tests reveal abnormal antibodies, the doctor will assess the patient’s medical history to determine whether previous symptoms may have been caused by antiphospholipid syndrome.
Treatment and medications
- Although there’s no cure for APS, the risk of developing blood clots can be greatly reduced if it’s correctly diagnosed.
- An anticoagulant medicine such as warfarin or an antiplatelet such as low-dose aspirin is usually prescribed. These reduce the likelihood of unnecessary blood clots forming but still allow clots to form when you cut yourself.
- Treatment with these medications can also improve a pregnant woman’s chance of having a successful pregnancy. With treatment, it’s estimated there’s about an 80% chance of having a successful pregnancy.
- Most people respond well to treatment and can lead normal, healthy lives. However, a small number of people with APS continue to experience blood clots despite extensive treatment.
Treatment during pregnancy
- A woman with a diagnosis with APS should plan for pregnancy from before conception. Treatment will start at the beginning of pregnancy and finish after delivery.
- In an unplanned pregnancy, the effectiveness of treatment may be reduced as it will not begin until several weeks after conception.
- Treatment will normally be aspirin, heparin, or both, depending on previous clots of pregnancy complications. Warfarin can cause birth defects, and it is not used during pregnancy.
- If the patient does not respond to this treatment, intravenous immunoglobulin infusions and corticosteroids, such as prednisone, may be prescribed.
- If, by the third trimester, there are no problems, the heparin treatment may stop, but the aspirin treatment may have to continue until the end of the pregnancy.
- Regular blood tests will need to continue to ensure the blood can still clot enough to stop bleeding if the patient bruises or cuts herself.
A patient with APS needs to take all possible measures to lower the risk of developing blood clots.
- Not smoking
- Maintaining a healthy bodyweight
- Remaining physically active