Combination of Aspirin and an Anti-Clotting Drug Reduces Risk of Dialysis Access Failure
For the first time, a combination of aspirin and the anti-platelet drug dipyridamole has been shown to significantly reduce blockages and extend the useful life of new artery-vein access grafts used for hemodialysis, according to a study by the Dialysis Access Consortium (DAC).
Balintfy: People with severe kidney disease, also known as kidney failure, need some form of kidney replacement therapy to survive.
Dr. Meyers: The most common form in the United States is hemodialysis.
Balintfy: Dr. Catherine Meyers is with the National Institute of Diabetes and Digestive and Kidney Diseases.
Dr. Meyers: And as its name implies, it is a procedure that requires access to blood vessels so that blood is actually removed from the patient, is then treated in a dialysis machine, and then returned through the blood vessels to the patient.
Balintfy: Dr. Meyers explains that there are different ways for physicians to set up what is called an "access" for hemodialysis.
Dr. Meyers: One is a temporary catheter, which is typically placed in one of the large vessels near the neck area. But catheters are considered temporary, because they can become infected or readily pulled out. There are also problems with clotting; they typically don't last that long—they need to be replaced—so it's considered what we call a temporary access. By in large, patients that are treated chronically with hemodialysis need either an AV fistula or an AV graft. Balintfy: Artery-vein access grafts, or A-V grafts, fail most often due to narrowing of blood vessels at the graft site, and subsequent clotting, which block the flow of blood. A blocked graft cannot be used for dialysis and is a major cause of worsening health in dialysis patients.
Dr. Meyers: When the graft fails, it requires either an invasive radiology procedure to try to fix the graft, or patients need another surgery. And it's a tremendous burden on patients when an access fails, because they are therefore committed to further invasive procedures and additional surgeries.
Balintfy: Now a new study has demonstrated that using a particular drug combination—in this case, dipyridamole and aspirin—extends the life of an AV graft once it's created. Dr. Meyers adds that it's a small increase in the lifespan; an 18 percent reduction in the risk that the graft would fail once the patient was started on the drug therapy.
Dr. Meyers: But it's an important step for physicians who care for these patients, because to date there have no other therapies available to try to extend the life of grafts. And in particular, we have a pretty good notion of how drugs like dipyridamole and aspirin work on the access. And certainly additional therapies that would target that particular pathway in a graft may provide new therapies that would have even larger impact on outcomes in grafts. So it's given us a large trial with a significant effect, although it's a modest effect, but it's still is the only therapy that we have demonstrated at this point, pharmacological therapy with the drug, that shown that we can help some of these outcomes, because the failure rate is just so high with AV grafts across the board.
Balintfy: The study, by the Dialysis Access Consortium, included a total of 649 participants with new AV grafts at 13 clinical sites in the United States. They were randomly assigned to treatment with the drug combination, or to a placebo. The trial took place over a five-year period. For more information on this study and kidney disease, visit www.niddk.nih.gov. This is Joe Balintfy, National Institutes of Health, Bethesda, Maryland.