Factor XI Antisense Oligonucleotide as High-Potential Thrombus Prevention vs. Conventional Therapy
With the dangers accompanied by venous thromboembolism in patients undergoing total knee arthroplasty,a study in Amsterdam led by Dr. Harry R. Büller about comparing the efficacy of Factor XI Antisense Oligonucleotide (FXI-ASO) in preventing venous thromboembolism compared to the conventional therapy was conducted.

Parameters of efficacy utilized by the study for comparison include bleeding episodes, coagulation time, and non-inferiority of FXI-ASO therapy compared to enoxaparin, which is the current treatment modality. The study was published in The New England Journal of Medicine (NEJM) on December 7, 2014.

Arthroplasty is the surgical reconstruction or replacement of any joints in the body. This procedure is usually done in patients suffering from osteoarthritis (arthritis of the joints of the weight-bearing bones), with knee pain and hip pain being the usual complaint of the patients. When a patient with knee arthritis or hip arthritis undergoes arthroplasty, there is a chance that clots will develop along the wall of the vein at the site of surgery and if not assessed carefully, these clots can be dislodged and can cause disruption in the circulation of the part where it clogged such as the lungs and the brain. Once a venous thrombus dislodges, it is now called as an embolus.
The period covered by the study was from July 2013 to March 2014 and had utilized a total of 300 samples. Patients utilized as samples are ages 18 to 80, all undergoing elective primary unilateral total knee arthroplasty. Main exclusion criteria include the following: active bleeding or high-risk bleeding, below 50 kg body weight, kidney and liver dysfunctions, and history of brain and spinal surgery. These samples underwent randomization in either one of two regimens of FXI-ASO (200 mg or 300 mg), and later on, the current treatment regimen of enoxaparin. Series of visualization tests and blood work-ups were gathered and analyzed.

It was found out that 30% in the enoxaparin group developed venous thromboembolism, 27% in the 200-mg FXI-ASO group, and only 4% in the 300-mg FXI-ASO group. Therefore, both regimens proved to be non-inferior to enoxaparin. Second criterion for comparison is the presence of bleeding episode. Clinically relevant bleeding occurred in 8% of the enoxaparin group compared to 3% in both two regimens of FXI-ASO. Third criterion for comparison is the coagulation time. It was found out that FXI-ASO contributed to post-operative venous thromboembolism and lowering its amount appeared to be safe for preventing clot formation. Also, the high-specificity property of FXI-ASO is a great advantage since it does not affect other clotting factors.

However, the study poses some weaknesses too. First, a bigger sample must be utilized to provide a stronger conclusion about bleeding instances. Second, additional studies may be needed to prove the safety of FXI-ASO as treatment to patients who will undergo knee replacement, hip replacement or arthroplasty.

In conclusion, FXI-ASO shows promising result as lowering its level prevents formation of clots without causing clinically significant bleeding or triggering hemostasis.

If you have been told that you are in need of a knee replacement or hip replacement, contact our orthopedic specialists at Orthopedic Surgery San Diego today.