A recently introduced test can help be helpful in identifying which people who have had one blood clot in a vein will be likely to have another one.
According to the scientists, this discovery could help people at low risk avoid anticoagulant therapy, which can bring about serious side effects, whilst ensuring that patients at high risk who require the treatments receive them.
Anticoagulant treatment for people suffering from venous thromboembolism - the formation of blood clots, usually concerning the deep veins of the legs or the lungs – is made up of the blood-thinner heparin followed by vitamin K antagonists for at least three to six months.
The scientists said that even then, over thirty per cent of the patients will have a clot recurrence within five to eight years, and around five per cent of these will be deadly.
The research is published in the July 26 issue of the Journal of the American Medical Association.
Protein suggests risk
In their research, Dr Gregor Hron and his colleagues at Medical University of Vienna, Austria, concluded that by measuring the production of thrombin - a protein in blood causing clotting - patients can be classified as "great risk" and "low risk" for return of venous thromboembolism.
914 patients suffering from preliminary venous thromboembolism - vein clots - were followed for an average of forty seven months after they gave up vitamin K antagonist therapy; a hundred of them experienced a second clot.
The scientists discovered that about 66 per cent of the patients had low thrombin generation and 60 percent decreased the risk of experiencing a new clot, in comparison to one-third of the patients with high thrombin generation.
"Using an uncomplicated, commercially available laboratory method created in order to measure thrombin generation, we were able to recognize patients in whom the long-term risk of recurring venous thromboembolism is pretty negligible," the authors wrote.
"Considering the rate of occurrence of serious or even fatal haemorrhage associated with anticoagulant therapy and the case fatality rate of repeated venous thromboembolism, patients with low peak thrombin generation would almost surely not take advantage of indefinite anticoagulant therapy. As a result, extensive thrombophilia screening turns up to be not needed in this large group of patients at low risk," the scientists concluded.
Methods of researching questioned
One specialist called the research ‘intriguing’, however he questioned the methods used by the investigators.
"This well-respected study group from Vienna has framed one of the most relevant questions concerning long-term management of deep venous thromboembolism and pulmonary embolism: Is that possible that a simple blood test can predict recurrence after stopping anticoagulation? The answer turns up to be ‘yes,’" claimed Dr Samuel Goldhaber, director of the venous thromboembolism study group at Brigham and Women’s Hospital, in Boston.
"Nevertheless, the only problem is that the blood test was not carried out until thirteen months after discontinuing anticoagulation, rather than being used at the time a decision was being made whether to maintain anticoagulation. Nonetheless, the results of the research are intriguing and significant," he explained.
Another specialist said that there already exist tests predicting the return of venous thromboembolism.
According to Dr Jack E. Ansell, a professor of medicine at Boston University School of Medicine, the discovery is not new. "We already have one test that has proven to predict recurrence - the D-dimer assay," he said. "An increased D-dimer after stopping anticoagulation will forecast recurrence."
"The D-dimer assessment is commonly available and is used nowadays by many healthcare professionals as a risk index for recurrent venous thromboembolism," he added.
