Understanding the problem

Antiphospholipid antibodies are abnormal proteins produced by the immune system that mistakenly attack proteins that are attached to fats called "phospholipids" found within the lining of blood cells and blood vessels. These antibodies can increase a person's risk of developing a blood clot within arteries and veins and can cause women to have difficulty having successful pregnancies. APLAS is rare and testing for the antibodies should only be done when doctors have a strong suspicion of APLAS and if knowledge of the test result will change how the patient is managed (i.e. should not be routinely done after a DVT or PE).

There are three different types of antiphospholipid antibodies that can be detected using blood tests. People who have positive tests for all three types of antibodies are called "triple-positive". They have the highest risk of developing blood clots in their arteries and veins as well as the highest risk of having new blood clots despite taking anticoagulants.

People who take warfarin (an anticoagulant) need to have regular blood measurements, called an INR, to ensure the medication dose is correct.  Warfarin may interact with food and lots of other medications. For these reasons, some people dislike taking warfarin. Xarelto® is an anticoagulant pill that does not require blood testing and interacts with very few medications, which is why some people prefer to take it instead of warfarin.

The question asked by researchers for this study was, “Is it safe and effective for patients with triple-positive APLAS who have a history of blood clots to take Xarelto® instead of warfarin to prevent new blood clots?”