Reducing Blockage Fails to Improve Access
to the Bloodstream for Kidney Dialysis
Reducing early blockages in bloodstream access for kidney failure
treatment does not increase the likelihood that the access will
function adequately for long-term treatments, according to a study
funded by the National Institutes of Health. Results were published
May 14, 2008, in the Journal of the American Medical Association.
"Since most of the 470,000 Americans with kidney failure depend
on hemodialysis for survival, there is a clear and compelling need
to evaluate therapies that reduce or prevent access failure," said
NIH Director Elias A. Zerhouni, M.D. "These results tell us we
need to keep looking for solutions."
Hemodialysis filters waste and extra fluid from the bloodstream
and requires a vascular access — a site on the body where
blood is removed and returned. Fistulas are the preferred type
of access since they clot less often, experience fewer infections,
and are less costly; patients with fistulas also have lower mortality.
A fistula is created by joining a section of an artery and a vein
to make one large vessel capable of handling high volumes of blood
during hemodialysis. But maintaining any access site is a major
clinical challenge. Blood clotting in the fistula is the most frequent
cause of early fistula failure. Clotting, infection and low blood-flow
rates in the access site are common reasons for hospitalizations
requiring multiple treatments or surgeries. Read about vascular
access at http://kidney.niddk.nih.gov/kudiseases/pubs/vascularaccess.
The Dialysis Access Consortium (DAC) found that only 12 percent
of patients developed blood clots in the fistula when treated with
the clot-preventing drug clopidogrel, compared to nearly 20 percent
of patients treated with placebo. Nevertheless, about 60 percent
of new fistulas in each group could not be used for long-term dialysis
treatments. Complications such as bleeding were similar across
the study groups.
DAC studied nearly 900 patients at 9 U.S. medical centers in academic
and community practices in urban and rural settings. Participants
received a new fistula and took the anti-platelet drug clopidogrel
(Plavix) or a placebo tablet daily for 6 weeks to determine if
the drug would maintain blood flow in fistulas and increase the
number suitable for dialysis.
"Because vascular access is critical for delivering lifesaving
care, we are already organizing another multi-center study to look
for other ways to improve fistulas," said co-author Catherine M.
Meyers, M.D., a kidney specialist in charge of DAC at NIH’s National
Institute of Diabetes and Digestive and Kidney Diseases (NIDDK),
which funded the study.
The DAC Fistula Trial is the largest multi-center trial to look
at preventing blood clots in new fistulas and the first to test
whether prevention would allow more fistulas to be useable for
dialysis. NIDDK has funded DAC since 2000. Clopidogrel and placebo
were donated by what is now Sanofi Aventis/Bristol-Myers Squibb.
The National Institute of Diabetes and Digestive and Kidney Diseases,
a component of the NIH, conducts and supports research in diabetes
and other endocrine and metabolic diseases; digestive diseases,
nutrition, and obesity; and kidney, urologic, and hematologic diseases.
Spanning the full spectrum of medicine and afflicting people of
all ages and ethnic groups, these diseases encompass some of the
most common, severe, and disabling conditions affecting Americans.
For more information about NIDDK and its programs, see www.niddk.nih.gov.
The National Institutes of Health (NIH) — The Nation's
Medical Research Agency — includes 27 Institutes and
Centers and is a component of the U.S. Department of Health and
Human Services. It is the primary federal agency for conducting
and supporting basic, clinical and translational medical research,
and it investigates the causes, treatments, and cures for both
common and rare diseases. For more information about NIH and
its programs, visit www.nih.gov.