A test that measures the generation of a certain protein involved with blood clotting can help determine whether patients who have experienced a venous blood clot are at low risk of developing another blood clot, and thus avoiding anticoagulant treatment and its possible side effects, according to a study in the July 26 issue of JAMA.
Anticoagulant treatment for patients with venous thromboembolism (VTE - formation of blood clots, often involving the deep veins of the legs or in the lung) consists of heparin followed by vitamin K antagonists for at least 3 to 6 months. After discontinuation of anticoagulant treatment, a third of patients experience recurrence of VTE within the next 5 to 8 years, according to background information in the article. The case-fatality rate of recurrence is around 5 percent. Therefore, identification of patients who might benefit from indefinite anticoagulant treatment (i.e., patients in whom recurrent VTE is more likely than anticoagulation-associated severe bleeding) is now one of the foremost goals in thrombosis research. Because of the large number of risk factors, assessing the risk of recurrence in an individual patient is complex. A laboratory test that would detect multifactorial thrombophilia (increased tendency for blood clots) could help determine the overall risk of recurrent VTE.
Gregor Hron, M.D., of the Medical University of Vienna, Austria and colleagues conducted a study to determine whether by measuring thrombin generation (a protein in blood that causes clotting), patients with VTE could be stratified into high- and low-risk categories for recurrence of VTE. The study, conducted between July 1992 and July 2005, included 914 patients with first spontaneous VTE who were followed-up for an average of 47 months after discontinuation of vitamin K antagonist therapy. Thrombin generation was measured by a commercially available test.