Elderly atrial fibrillation patients may see little benefit from anticoagulants

For years, physicians have tried to prevent strokes by prescribing blood thinners to heart patients diagnosed with atrial fibrillation. But a recent study shows the typical patient after age 87 won’t benefit from taking warfarin, one of the best known oral anticoagulation medications for individuals with an irregular heartbeat. For patients taking apixaban, a direct oral anticoagulant, there is also little benefit after the age of 92.

“As patients age, the net clinical benefit of anticoagulation therapy compared to no treatment diminishes,” said Dr. Mark Eckman, Posey Professor of Clinical Medicine at the University of Cincinnati College of Medicine, and senior author of the study. “We ought to think twice in the very elderly about whether it is really worth starting them on blood thinning therapy.”

“The major side effect of all anticoagulants is bleeding since their role is to thin the blood and hopefully combat the risk of stroke,” said Eckman.

The study, titled “The Net Clinical Benefit of Oral Anticoagulation among Older Adults with Atrial Fibrillation,” is available online in the American Heart Association’s scholarly journal Circulation: Cardiovascular Quality and Outcomes. It uses a computerized decision analytic model first developed by Eckman known as Atrial Fibrillation Decision Support Tool (AFDST) which was used by researchers at the University of California, San Francisco; Massachusetts General Hospital and Kaiser Permanente to simulate health outcomes for 14,946 patients age 75 and older with atrial fibrillation. 

Atrial fibrillation, an irregular and often rapid heart rhythm, affects more than 10% of the population age 70 and older, explains Eckman. It also presents a strong risk factor for stroke due to clots forming in the left atrium that then travel to the rest of the body including the brain.

The AFDST allows physicians to simulate through a computer model clinical outcomes for atrial fibrillation patients receiving any form of anticoagulant therapy versus no treatment and delivers an estimated life expectancy for each treatment strategy. The results are presented as quality adjusted life years — a calculation that accounts for both length of life and quality of life in the health states that may occur over the simulated lifetime of the patient.

“You get life expectancy adjusted for quality-of-life,” said Eckman. “If a patient spends two years in poor health following a severe stroke, for instance, each year of life is only worth some fraction of a quality-adjusted year. Thus the model can account for the diminished quality of life that may occur if a stroke or major bleeding event occurs.”

Dr. Sachin Shah, assistant professor of clinical medicine at the University of California, San Francisco, is the lead researcher in the study.

“Many prior studies looking at the benefit of blood thinners found older adults benefit more than younger adults, but they narrowly focus on atrial fibrillation and strokes and don’t account for all other health conditions affecting older adults,” explains Shah. “Our study is the first to find that when taking these factors into consideration, anticoagulant benefit actually decreases with age.”

Eckman’s AFDST uses the patient’s age; gender; diagnosis of congestive heart failure, hypertension, diabetes and vascular disease; a history of stroke, bleeding, intracranial hemorrhage; myocardial infarction or heavy alcohol use along with abnormal liver or kidney laboratory tests to calculate the yearly rate of stroke or major bleeding and bleeding into the brain using several validated risk prediction tools. 

The AFDST has been in use at the University of Cincinnati for the past three years and is integrated into UC Health’s electronic health record system.

“Patients with a high risk of stroke and low risk of bleeding benefit the most from anticoagulant therapy,” says Eckman. 

National as well as local data suggest that physicians aren’t providing appropriate blood thinning therapy for a large enough portion of patients with atrial fibrillation, says Eckman. Only 60% of patients with atrial fibrillation are getting blood thinning therapies with anticoagulants, so there is “under treatment” when it comes to stroke prevention.

“For years we have been telling our doctors and patients that we are not being aggressive enough in providing anticoagulant therapy to our patients with atrial fibrillation, and it’s a national problem,” said Eckman. “This study now adds a caution, acknowledging that while under treatment is a major concern, at advanced years of age maybe we should be a little more thoughtful and careful in our treatment decisions about anticoagulation.”

Other researchers participating in the study include Dr. Daniel Singer, Massachusetts General Hospital and professor of medicine at Harvard Medical School; Dr. Margaret Fang, professor of medicine at the University of California, San Francisco; Kristi Reynolds, director of epidemiologic research at the Department of Research and Evaluation, Kaiser Permanente Southern California; and Dr. Alan Go, regional director of Kaiser Permanente Northern California clinical trials program and professor at the University of California, San Francisco.

The study was funded by the National Institutes of Health (NIH) National Center for Advancing Translational Sciences (NCATS UL1TR000077-05); National Heart, Lung, Blood Institute (U19HL91179, 1RC2HL101589); and National Institutes on Aging (R01 AG15478). Shah was partly supported by the UCSF Division of Hospital Medicine, and Singer was partly supported by the Eliot B. and Edith C. Shoolman Fund of Massachusetts General Hospital. 

Eckman has current or recent investigator-initiated grant funding from the Heart Rhythm Society through a grant from Boehinger-Ingelheim Pharmaceuticals, Inc., NCATS (UL1TR000077-05), NIH National Institute of Child Health and Human Development (R01HD094213), Virus Action Coalition of the Centers for Disease Control, Merck, Pfizer Educational Group, Bristol-Myers Squibb/Pfizer Education Consortium, and the Cystic Fibrosis Foundation.

Go has a research grant through Kaiser Permanente Northern California Division of Research from iRhythm Technologies. Reynolds has received research support through Kaiser Permanente Southern California Department of Research & Evaluation from iRhythm Technologies.

Singer receives research support from Bristol-Myers Squibb and Boehringer-Ingelheim and serves as a consultant or an advisory board member for Bristol-Myers Squibb, Boehringer-Ingelheim, CVS Health, Johnson and Johnson, Merck and Pfizer.