Press Releases: Northern California
August 2, 2006
Age Does Not Increase Bleeding Risk Associated with Blood Thinners
Study Suggests That Older Patients With Atrial Fibrillation Can Safely Continue Well-Managed Warfarin Therapy
OAKLAND, Calif. – For people with atrial fibrillation, older age is a risk factor for developing bleeding in the brain, regardless of whether or not they are taking the blood-thinning medication warfarin. That’s the finding of a new study in the August 10th issue of the Journal of the American Geriatric Society.
The study findings are reassuring because they show the overall risk of hemorrhage is still fairly low, said Alan S. Go, MD, a physician investigator with Kaiser Permanente and one of the authors of the study. He explained that carefully monitored warfarin therapy can be used with reasonable safety – even in older patients with atrial fibrillation – to reduce their risk of a life-threatening stroke.
Warfarin is a blood-thinning medication that helps prevent the formation of blood clots, which can cause strokes in people with atrial fibrillation, a heart rhythm disorder. Previous studies have shown that anticoagulation therapy reduces the risk of a stroke by more than 60 percent in patients with atrial fibrillation, but also causes an increase in the risk for a major hemorrhage. The most serious type of hemorrhage is bleeding into the brain, also called intracranial hemorrhage.
“Overall the risk is very low for this kind of problem” said Go, “but it’s still one we have to take seriously because the consequences of any kind of bleeding in the brain, at any age, are so potentially devastating."
The research, done as part of the AnTicoagulation and Risk Factors In Atrial Fibrillation (ATRIA) Study, was carried out by investigators at Kaiser Permanente’s Division of Research in Oakland, California; the University of California at San Francisco; Boston University School of Medicine; and Massachusetts General Hospital, Boston.
The researchers followed 13,559 adults aged 18 and older at Kaiser Permanente of Northern California who were being treated for atrial fibrillation.. The researchers found the older the patient, regardless of whether they were on warfarin, the more likely they were to experience a hemorrhage. Those younger than 60 who were on warfarin had about a 0.4 percent chance of suffering an intracranial hemorrhage (which means that out of 1,000 people under age 60 taking warfarin, 4 were likely to have a hemorrhage). In comparison, those under 60 not taking warfarin had only a 0.12 percent risk of experiencing bleeding in the brain. By age 80 and older, the gap between those two numbers had virtually disappeared, and both warfarin and non-warfarin patients had approximately a 0.7 percent risk of hemorrhage.
Other researchers involved in this study include Nancy G. Jensvold, MPH, Kaiser Permanente Division of Research, Oakland, California; Margaret C. Fang, MD, MPH, UCSF; Elaine M. Hylek, MD, MPH and Lori E. Henault, MPH, Boston University School of Medicine, Boston, Massachusetts; Yuchiao Chang, PhD, and Daniel E. Singer, MD, Massachusetts General Hospital, Boston, Massachusetts.
The Kaiser Permanente Division of Research conducts, publishes, and disseminates epidemiologic and health services research to improve the health and medical care of Kaiser Permanente members and the society at large. It seeks to understand the determinants of illness and well being and to improve the quality and cost-effectiveness of health care. Currently, DOR’s 400-plus staff is working on more than 250 epidemiological and health services research projects.
Kaiser Permanente is America’s leading integrated health plan. Founded in 1945, it is a not-for-profit, group practice program headquartered in Oakland, Calif. Kaiser Permanente serves more than 8.5 million members in nine states and the District of Columbia. Today it encompasses the not-for-profit Kaiser Foundation Health Plan, Inc., Kaiser Foundation Hospitals and their subsidiaries, and the for-profit Permanente Medical Groups. Nationwide, Kaiser Permanente includes approximately 154,000 technical, administrative and clerical employees and caregivers, and more than 12,000 physicians representing all specialties.
The study was supported by a Public Health Services research grant from the National Institute on Aging, the Eliot B. and Edith C. Shoolman Fund of Massachusetts General Hospital, and a Hartford Geriatrics Health Outcomes Research Scholars Award from the American Geriatrics Society Foundation for Health in Aging. Researcher Elaine Hylek received grant support from Bristol-Myers Squibb, the makers of Coumadin.
UCSF is a leading university that consistently defines health care worldwide by conducting advanced biomedical research, educating graduate students in the life sciences and providing complex patient care.
