Which blood thinner is most effective at preventing blood clots and a second stroke in patients with APS?

This study compared different treatments for the prevention of blood lots and stroke in patients with anti-phospholipid syndrome (APS). They found that warfarin (Coumadin) is more effective at preventing stroke than other blood thinners.

APS is a disorder of the immune system which leads to excessive blood clotting. Blood clots can form in any artery or vein leading to leg and lung clots, stroke, or miscarriage. Treatments to prevent clots include anticoagulants (which alter the process of blood clotting) and antiplatelets (which stop cells in the blood from clumping together). There are two types of anticoagulants: warfarin and NOACs. Warfarin interferes with vitamin K which is important for blood clotting. NOACs are a  family of drugs that interfere with a protein involved with blood clotting. Rivaroxaban (Xarelto) is a member of the NOAC family.

NOACs are now being used more frequently because unlike warfarin they do not need regular monitoring. However, it is not clear whether they are as effective as warfarin in the management of APS.

This study compiled the results of 8 studies with a total of 811 participants. Participants were treated with different combinations of blood thinners and monitored for the development of clot-related events such as stroke or miscarriage. 

Patients taking rivaroxaban were 14.13 times more likely to suffer a stroke than patients taking warfarin. There was no significant difference in the risk of bleeding between rivaroxaban and warfarin.

Patients taking high-dose warfarin had the same risk of clots as those taking standard-dose warfarin. However, they were more likely to have problems with bleeding. 

Standard-dose warfarin combined with antiplatelets such as aspirin was associated with an increased risk of both clotting and bleeding compared to standard-dose warfarin alone.

This study showed that standard dose warfarin may be the safest and most effective treatment for clot prevention in APS. 

Some of the evidence included in this study was not of high quality. More studies are needed to confirm these results.