Blood clotting, or coagulation, is an important process that prevents excessive bleeding when a blood vessel is injured. Sometimes, however, clots form on the inside of vessels without an obvious injury or do not dissolve naturally, a potentially life-threatening situation requiring treatment. Research presented today at the 51st Annual Meeting of the American Society of Hematology reveals that the practice of using the anticoagulants aspirin and heparin with the hope of preventing clots in placental blood vessels is ineffective for preventing unexplained, recurrent miscarriages. Two other studies look at treatments for venous thromboembolism, a common and sometimes deadly clotting disorder.
“Anticoagulants are one of the most common types of medications in use today and help prevent and treat a wide variety of health conditions,” said Bradford S. Schwartz, MD, moderator of the press conference highlighting this research and Professor of Medicine and Biochemistry, and Dean of the University of Illinois College of Medicine at Urbana-Champaign. “That’s why it’s so critical that studies examining both newer formulations and old standbys, like aspirin, provide practitioners with the most up-to-date evidence to ensure that they are being used appropriately and that the best option is chosen for each individual patient.”
A new study provides welcome news for patients with a common clotting disorder known as venous thromboembolism (VTE). According to the Venous Disease Coalition, 1 million Americans experience VTE every year, which occurs when an abnormal clot forms in a vein and restricts the flow of blood, causing pain and swelling. In some cases, the clot may detach from its point of origin and travel through the heart to the lungs, causing a potentially fatal condition known as a pulmonary embolism.
Currently, patients with VTE are treated with a blood thinner known as warfarin, which has many burdensome interactions with other medications and foods and requires frequent monitoring of the dosage. However, this study shows that an oral drug called dabigatran etexilate, which does not have these disadvantages, is as safe and effective as warfarin for combating VTE.
To compare the two drugs, an international team of researchers conducted a randomized, double-blind trial of 2,539 patients with acute VTE. For six months, roughly half of the patients in the trial (1,274) were given a fixed dose of 150 mg of dabigatran etexilate twice daily, while the other half (1,265 patients) were given warfarin once daily in doses adjusted to an International Normalized Ratio (INR) of 2.0 to 3.0. INR is a blood test needed to monitor the effects of warfarin therapy to ensure an adequate, yet safe, dose is taken; in this study, the test was performed, on average, every 11 days.
The improvement seen in both groups from the treatments was similar. After six months of treatment, only 2.4 percent of the dabigatran etexilate group (30 patients) and 2.2 percent of the warfarin group (27 patients) experienced recurrent VTE. The safety of the two drugs was also comparable. In the dabigatran etexilate arm, 207 patients experienced bleeding (including 20 patients with major bleeding) versus 280 patients in the warfarin arm (including 24 with major bleeding). Other possible side effects, including death, acute coronary syndromes, and abnormalities in liver function tests, were infrequent in the two groups.
“We are excited by these findings and feel that they will change the standard of care for venous thromboembolism, which affects a large number of our patients,” said lead study author Sam Schulman, MD, Professor of Medicine, Thrombosis Service, McMaster Clinic and Hamilton General Hospital in Ontario, Canada. “This study found that dabigatran is a safe and effective anticoagulant that does not require the routine monitoring or dose adjustments that are necessary with warfarin. In other words, patients can receive the same results in a more convenient manner.”
