Doctor, can I take Xarelto® instead of warfarin to treat my blood clot caused by triple-positive antiphospholipid antibody syndrome?

No. Patients with a blood clot caused by antiphospholipid antibody syndrome (APLAS) who received Xarelto® developed more blood clots that caused strokes and heart attacks than patients who received warfarin. Warfarin remains the best treatment for most patients with APLAS.

Study highlights

This study was stopped early because patients who received Xarelto® had more new blood clots than patients who received warfarin.

Note: Not all patients with APLAS are triple-positive, and the results of taking Xarelto® in patients who are only positive for 1 or 2 antiphospholipid antibody types are unknown

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?”

Who? The study included 120 people aged 18-75 years (average 46 years; 64% female) who had triple-positive APLAS and a history of a blood clot in a vein or artery

What? The study measured the rates of new blood clots, major bleeding, and death due to blood clots in patients who received Xarelto® compared with patients who received warfarin




Xarelto® 20 mg once a day


Xarelto® 15 mg once a day, in patients with kidney disease

Warfarin adjusted to maintain a target INR between 2 and 3

Xarelto® compared with warfarin in patients with triple positive APLAS

Outcomes at

20 months

(120 patients)

Rate of events with Xarelto®

(59 patients)

Rate of events with warfarin

(61 patients)


Arterial blood clot (stroke or heart attack)

12 out of 100 people

0 out of 100 people

About 12 more people out of 100 had an arterial blood clot while taking Xarelto®

Venous blood clot (DVT or PE)

0 out of 100 people

0 out of 100 people

No difference

Major bleeding7 out of 100 people3 out of 100 people

No difference*

Death0 out of 100 people0 out of 100 peopleNo difference

*Although the rates for the 2 groups look different, the differences were not statistically significant—this means that the difference could be due to chance or to the small number of patients studied rather than due to the different treatments.

This Evidence Summary is based on the following article:

Pengo V, Denas G, Zoppellaro G, et al. Rivaroxaban vs warfarin in high-risk patients with antiphospholipid syndrome. Blood. 2018 Sep 27;132(13):1365-1371. doi: 10.1182/blood-2018-04-848333. Epub 2018 Jul 12. PubMed

Published: Friday, March 8, 2019
Last Updated: Thursday, July 30, 2020