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."
This press conference will take place on Sunday, December 6, at 8:00 a.m.
Dabigatran Etexilate Versus Warfarin in the Treatment of Venous Thromboembolism
[Abstract #1]
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."
Dr. Schulman will present this study during the Plenary Scientific Session on Sunday, December 6, at 2:00 p.m. in Hall F.
Aspirin and Aspirin Combined With Low-Molecular-Weight Heparin in Women with Unexplained Recurrent Miscarriage: A Randomized Controlled Multicenter Trial (ALIFE Study)
[Abstract #488]
Recurrent miscarriages are extremely traumatic and stressful for women, and, according to the American Society for Reproductive Medicine, the cause is unknown in more than 50 percent of cases. Though treatments to avoid these tragedies remain elusive, some practitioners suspect that abnormal clots in the blood vessels that nourish the placenta are responsible for many recurrent miscarriages, and thus they have increasingly used aspirin and low-molecular-weight heparin to prevent further miscarriages, even though evidence to support their use is not available. Both medications are blood thinners and are used to prevent clots in the placenta that could cut off the supply of nutrients to a growing baby, or to decrease the risk of other pregnancy complications that might be causing the miscarriages.
To test the effectiveness of these controversial treatments, a team of researchers from the Netherlands conducted a multicenter, randomized clinical trial of 364 women between the ages of 18 and 42 who were attempting to conceive or were less than six weeks pregnant. The women had previously experienced at least two unexplained miscarriages by the 20th week of pregnancy. Because the researchers were focused on miscarriages with unexplained causes, women with previous venous or arterial thromboembolism (clotting disorders), endocrine disorders, or other indications for anticoagulant treatment during pregnancy were excluded from the study.
"The study clearly demonstrates that aspirin combined with heparin and aspirin alone do not prevent recurrent, unexplained miscarriages and that we should not needlessly put these women through the inconvenience and risks associated with these blood-thinning medications," said lead study author Stef P. Kaandorp, MD, research fellow in the Department of Obstetrics and Gynecology at the Academic Medical Center in Amsterdam. "These results are extremely important because they will likely change the way some women at high risk for another miscarriage have been treated."