Osteoporosis Drug Fosamax Linked to Atrial
Fibrillation in Older Women
Merck's Fosamax is most widely used drug for bone-thinning osteoporosis
April 29, 2008 - Older women who use Fosamax (alendronate)
to prevent fractures from osteoporosis are nearly twice as likely to
develop the most common kind of chronically irregular heartbeat (atrial
fibrillation), according to research from Group Health and the
University of Washington published in the April 28 Archives of Internal
Medicine, one of the JAMA/Archives journals.
Merck markets Fosamax, the most widely used drug
treatment for the bone-thinning disease osteoporosis, explained study
leader Susan Heckbert, MD, PhD, MPH. Dr. Heckbert is a professor of
epidemiology and scientific investigator in the Cardiovascular Health
Research Unit at the University of Washington.
The Food and Drug Administration (FDA) approved the
first generic versions (called alendronate) in February.
"We studied more than 700 female Group Health
patients whose atrial fibrillation was first detected during a
three-year period," said Dr. Heckbert. She and her colleagues compared
those women to over 900 randomly selected female Group Health members
matched on age and high blood pressure to serve as controls.
"Having ever used alendronate was associated with
an 86 percent higher risk of newly detected atrial fibrillation compared
with never having used the drug," said Dr. Heckbert, who is also an
affiliate investigator at the Group Health
Center for Health Studies.
Osteoporosis mostly affects older women and can set
the stage for fractures that can impair the quality of their lives, said
Dr. Heckbert.
"Careful judgment is required to weigh the risks
and benefits of any medication for any individual patient," she added.
"For most women at high risk of fracture, alendronate's benefit of
reducing fractures will outweigh the risk of atrial fibrillation."
However, said Dr. Heckbert, "women who are at high
risk of fractures but also have risk factors for atrial fibrillation,
such as heart failure, diabetes, or coronary disease, might want to
discuss alternatives to alendronate with their health care providers."
Other medications that can lower the risk of
fractures include estrogen, she said. But the Women's Health Initiative,
on which she has also served as an investigator, showed other heart
risks from hormone therapy combining estrogen with progesterone.
The National Heart, Lung, and Blood Institute funds
Dr. Heckbert's Atrial Fibrillation Study, which collects data on all
Group Health patients as they are first diagnosed with atrial
fibrillation. The study aims to find new factors that raise the risk of
developing this quivering of the heart's upper chambers (atria).
Atrial fibrillation occurs when the atria, the
smaller upper chambers of the heart, begin to beat irregularly and
rapidly.
Other recent studies have reported atrial
fibrillation as an unexpected adverse effect of bisphosphonates, a class
of drugs that includes alendronate and other medications that affect the
bodys calcium levels.
About one in 100 people and nearly nine in 100
people over age 80 have atrial fibrillation, said Dr. Heckbert. In
many cases, atrial fibrillation has no symptoms, and it isn't
necessarily life threatening. But it can cause palpitations, fainting,
fatigue, or congestive heart failure.
Atrial fibrillation can also make blood pool and
sometimes clot in the atria, said Dr. Heckbert. When parts of clots
break off and leave the atria, they can lead to embolic strokes, as
happens in over 70,000 Americans a year. That's why atrial fibrillation
is often treated with the anticoagulant warfarin.
Other results from her study have suggested that
maintaining a healthy body weight may help protect people from atrial
fibrillation.
"This study will help medical teams better inform
their patients about the risks associated with Fosamax, helping us make
the best treatment decisions for managing osteoporosis," commented
Christine Himes Fordyce, MD, a Group Health family practitioner.
"Now with this increased understanding of potential
irregular heartbeats, both physicians and their patients should be alert
to any problems, report them immediately, and treat them appropriately."
Editor's Note: This study was supported by grants
from the National Heart, Lung and Blood Institute. Co-author Dr.
Cummings has received research support from Amgen, Novartis, Lilly,
Pfizer and Zelos and consulting fees and honoraria from Amgen, Novartis,
Lilly, Zelos, Merck and P&G-Aventis.
Editorial: Risks and benefits of medications must
be balanced
The decision to treat an individual patient with a
given medication for a specific condition should be made with
consideration of the risks associated with no treatment and of the
benefits, risks and adverse effects of each therapy, write Jane A.
Cauley, Dr.P.H., and Kristine E. Ensrud, M.D., M.P.H, of the University
of Pittsburgh, in an accompanying editorial.
It is often overwhelming for patients to fully
understand the overall risks and benefits associated with different
therapies, they continue. Some researchers have suggested that a more
quantitative presentation of risks and benefits in terms of absolute
risk reduction, relative risk reduction or the numbers needed to treat
will improve patient understanding and facilitate shared decisions.
Future research should evaluate the effectiveness
of such strategies in presenting risks and benefits of therapies on
patient understanding, compliance and risk of health outcomes, they
conclude.
Editor's Note: Dr. Cauley has received research
support from Merck & Co., Eli Lilly & Co., Pfizer Pharmaceuticals and
Novartis Pharmaceuticals; has received consulting fees from Eli Lilly &
Co. and Novartis Pharmaceuticals; and is on the speakers bureau for
Merck & Co. Inc.
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April 29, 2008 - Older women who use Fosamax (alendronate)
to prevent fractures from osteoporosis are nearly twice as likely to
develop the most common kind of chronically irregular heartbeat (atrial
fibrillation), according to research from Group Health and the
University of Washington published in the April 28 Archives of Internal
Medicine, one of the JAMA/Archives journals.