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University of Iowa News Release


May 14, 2008

UI contributes to hemodialysis study that shows challenges remain

An anti-clotting drug reduced how frequently blood clots form in the fistula -- a surgically created blood vessel access needed for hemodialysis -- but did not improve overall fistula usability, according to a study led by the Dialysis Access Consortium that involved researchers from the University of Iowa and the Veterans Affairs Iowa City Health Care System.

The findings will appear in the May 14 issue of the Journal of the American Medical Association.

Most of the 470,000 Americans with end-stage kidney disease are treated with hemodialysis to remove toxins that build up in the blood when their kidneys fail. The procedure requires a vascular access, so blood from the patient can be removed, cleaned and returned, typically during three four-hour clinic sessions each week. An arteriovenous fistula, which directly connects a vein to an artery, has been considered the best access compared to two other methods that use plastic tubing.

"Fistula have fewer complications, lower costs and longest survival of any of the types of vascular access used for hemodialysis," said the study's principal investigator for the UI site, Brad Dixon, M.D., associate professor of internal medicine at the UI Roy J. and Lucille A. Carver College of Medicine. "However, they take longer to start or 'mature' into usable access points.

"The goal of the study was to prevent clotting to see if it improved the number of fistula that could be useable," added Dixon, who also is an investigator and staff physician with the VA Iowa City Health Care System. "While the study was highly successful at reducing the number of clotting fistula, nearly 60 percent of the fistula still did not meet our criteria for usability."

The study involved 877 participants with end-stage or advanced kidney disease who underwent surgical creation of a fistula. The UI partnered with the Renal Care Group, led by former UI fellow Tim Pflederer, M.D., in Peoria, Ill., to recruit 147 participants, making the UI and Peoria group partnership the second highest enrollment center in the consortium.

The researchers at all sites then assigned just more than half of the participants (441) to receive clopidogrel, the anti-clotting drug, while the other participants (436) received a placebo.

Six weeks after the study had begun, participants taking the anti-clotting drug had a 37 percent lower risk of clotting compared to the placebo group. However, of the 758 fistula able to be assessed for their suitability for dialysis, the percentage that ultimately failed was nearly the same in the two groups -- 61.8 percent for the anti-clotting group and 59.5 percent for the placebo group.

Dixon said the finding was surprising and has spurred researchers to look at why so many fistula fail to develop and seek new ways to improve that process.

"The vascular access is a hemodialysis patient's 'lifeline.' With increasing obesity and diabetes, and an aging population, kidney failure is increasing," Dixon said. "It's best to do a kidney transplant, but there are not enough organs available. Each year approximately 100,000 new patients develop end-stage kidney failure, but only about 2,500 can receive a transplant. The rest require dialysis to survive. It's important to find ways to improve the number of useable fistula."

In addition to Dixon, other UI contributors to the study included Lawrence Hunsicker, M.D., UI professor of internal medicine, as well as faculty from the Divisions of Transplantation and Hepatobiliary Surgery and Vascular Surgery in the UI Department of Surgery.

The study was funded by the National Institute of Diabetes and Digestive and Kidney Diseases of the National Institutes of Health.

To learn more about hemodialysis, visit this site at the National Institute of Diabetes and Digestive and Kidney Diseases:

STORY SOURCE: University of Iowa Health Science Relations, 5137 Westlawn, Iowa City, Iowa 52242-1178

MEDIA CONTACT: Becky Soglin, 319-335-6660,


STORY SOURCE: University of Iowa Health Science Relations, 5137 Westlawn, Iowa City, Iowa 5224-1178

MEDIA CONTACT: Becky Soglin, 319 335-6660