The net clinical benefit of anticoagulants
for atrial fibrillation (AF)—one of the most important causes of irregular
heartbeats and a leading cause of stroke—decreases with age, as the risk of
death from other factors diminishes their benefit in older patients, according
to a study led by researchers at UC San Francisco.
The multi-institutional study of nearly
15,000 AF patients found that the anticoagulant warfarin was not beneficial
after age 87 and another, apixaban, after age 92. As a result, physicians
should consider all mortality risks, such as cancer and end-stage kidney
disease, when recommending anticoagulants to older adults with AF, the researchers
said.
The study is online Nov. 11, 2019, in
Circulation: Cardiovascular Quality and Outcomes (CCQO), to coincide with a
presentation at the annual American Heart Association Scientific Sessions 2019.
"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," said lead author
Sachin Shah, MD, MPH, assistant professor of medicine at UCSF. "Our study
is the first to find that when taking these factors into consideration,
anticoagulant benefit actually decreases with age."
Atrial fibrillation affects an estimated 2.2
million Americans, according to the National Stroke Association, and about 15
percent of people who have strokes have AF. The stroke association estimates
that up to 80 percent of strokes among people with AF could have been
prevented.
While patients age 75 and older are at higher
risk for stroke and advised to use anticoagulants, there is little evidence of
their net benefit in this population. Advancing age also increases the
likelihood of death from non-AF causes, thereby limiting the benefit or harm
from AF and anticoagulant treatment.
Indeed, anticoagulant use in older patients
with atrial fibrillation is similar to prostate specific antigen (PSA) testing.
PSA testing is common in elderly men, despite evidence that those without
aggressive prostate cancer are unlikely to benefit from diagnosis and treatment
and may face significant risks for quality of life if they undergo prostate
surgery.
"Competing risk of death is an important
consideration when estimating the net clinical benefit of anticoagulation
therapy," Shah said. "Failing to account for competing risks likely
overestimates the net clinical benefit of anticoagulation, an effect that is
more pronounced at older ages and with more effective anticoagulants."
In the CCQO study, Shah and his colleagues,
including collaborators from Kaiser Permanente Northern and Southern
California, reviewed the records of 14,946 adults from January 2006 to June
2009 in the Anticoagulation and Risk Factors in Atrial
Fibrillation-Cardiovascular Research Network. They selected patients age 75 and
older, with an average age of 81.
The researchers used a computerized decision
analytic model called the Atrial Fibrillation Decision Support Tool (AFDST),
developed by the University of Cincinnati, to determine the potential benefit
of anticoagulants. The model uses patient characteristics and guidelines on AF
treatment from the American College of Cardiology, American Heart Association
and Heart Rhythm Society to offer a recommendation.
The research team estimated the lifetime net
clinical benefit of warfarin and apixaban relative to no treatment in
quality-adjusted life years (QALY). QALY is a measure of disease burden that
includes both the length of life and its quality, with one QALY equaling one
year in perfect health.
Using 0.10 lifetime QALYs as the minimal net
clinical benefit, warfarin started at 0.45 QALYs at age 75, then fell below
0.10 at age 87, while apixaban started at 0.74 QALYs at age 75, then fell below
0.10 at age 92.
"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 senior author Mark Eckman, MD, the Posey Professor of Clinical Medicine at the University of Cincinnati College of Medicine. "This study now adds a caution, acknowledging that while undertreatment 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."
Provided by University of California, San
Francisco
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