DENVER—Artery size is the only predictor of both primary and secondary patency in arteriovenous fistula (AVF) placement in hemodialysis (HD) patients, researchers reported at Renal Week 2010. The presence of diabetes predicted primary patency only.

Vascular access dysfunction is a major cause of morbidity and mortality in HD patients. Since the start of the Fistula First Initiative (FFI), the percentage of prevalent HD patients using AVFs has grown steadily. Yet, the fistula maturation rate continues to be poor, with up to 50% of fistulas placed never usable for dialysis.

Researchers at Mayo Clinic in Rochester, Minn., conducted the largest observational study of clinical predictors of AVF patency in the United States since the launch of FFI. The study included 293 patients (65% male) older than 18 years who had AVFs placed between January 2006 and December 31, 2008. The researchers defined primary failure AVF abandonment prior to use for HD and secondary failure as abandonment after use for HD.

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The mean age at fistula placement was 65.1 years and the mean BMI was 29.8 kg/m2.  The primary failure rate was 37.1% after exclusions (patients never requiring HD, died before use, transplanted prior to AVF use, or lost to follow-up). Of the AVFs suitable for dialysis, 11.4% failed during a median follow-up of 379 days. Complications occurred in 21.2% of patients. These included infection, bleeding, steal syndrome, aneurysm, never injury, seroma, and subclavian stenosis.

Artery size was the major predictor of both primary and secondary AVF patency. A history of diabetes predicted reduced primary patency or intervention-free survival only. The researchers found that age, gender, vascular disease, BMI, previous catheter use, vein size, or time on dialysis did not predict fistula patency.

“I was very surprised because I was thinking that female age would have an impact,” said lead investigator Carrie Grafft, MD, a nephrology fellow at Mayo. “Pre-operative ultrasound may be improving patient selection. So, maybe we are selecting out those older female patients with bad vessels and that is why we didn’t find that. We found that age is not associated with patency.”

If patency outcomes are considered alone, the possible patient characteristics and comorbidities other than artery size should not dissuade AVF placement, according to the investigators. Given the high fistula failure rate, elderly patients or patients with a shortened life expectancy may benefit from other vascular access strategies, the researchers noted.

More stringent criteria for artery size may be worth considering prior to AVF creation, Dr. Grafft said. “It may be possible to come up with a cut off point for artery size. We could determine it with an ultrasound.”