Less Inflammation with AVF

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C-reactive protein levels are lower with arteriovenous fistulas than with catheters.

SAN FRANCISCO—Arteriovenous fistulas (AVF) are associated with less chronic inflammation than catheters in adult and pediatric hemodialysis patients, according to a new study. The study is the first to investigate this association in both adults and children.

Researchers in Houston demonstrated that switching patients from catheters to AVF decreased chronic inflammation and that vascular access type may be a stronger determinant of inflammation than length of time on dialysis.

“These findings are something that has been suspected but had never been demonstrated in both children and adults,” said lead investigator Stuart Goldstein, MD, Medical Director of Dialysis at Texas Children's Hospital and associate professor of pediatrics at Baylor College of Medicine.

“We have always known that there is a risk for infection, but even when you don't have an infection, having a catheter in your vein is associated with chronic inflammation.  Since inflammation can lead to coronary calcification, we suggest that all efforts should be made to avoid catheters in patients receiving maintenance hemodialysis.”

Dr. Goldstein, who presented findings here during Renal Week 2007, and his colleague Juan Carlos Ayus, MD, evaluated associations between vascular access type (AVF, arteriovenous graft [AVG], and catheter) and C-reactive protein (CRP) levels in 118 adult hemodialysis patients.

In a separate study, CRP levels were evaluated in 35 other patients before and six months after they were switched from catheters to AVF. All patients received thrice-weekly hemodialysis for four hours and received aspirin therapy (81 mg a day). Catheter cultures were performed at the time of CRP assessment. The study excluded patients who had bacteremia, fever, or exit site infections.

Among the 118 patients in the cohort, 44 had AVF, 53 had AVG, and 21 had catheters. The AVF pa-tients had a mean age of 53 years and a mean 4.5 years on dialysis. The AVG patients had a mean age of 53 years and a mean 4.1 years on dialysis. The catheter patients had a mean age of 51 years and a mean 1.1 years on dialysis.

CRP levels were significantly lower for AVF (0.5 mg/dL) and AVG (1.6 mg/dL) patients than for catheter patients (4.1 mg/dL), a noteworthy finding given that the AVF and AVG patients had been on dialysis for much longer than the catheter patients, according to Dr. Goldstein. Furthermore, the presence or absence of diabetes did not affect CRP levels. Serum hemoglobin and albumin levels were significantly lower for patients with catheters.

After controlling for time on dialysis, the researchers found that CRP levels were lower for AVF patients than for catheter patients. In addition, the 35 patients switched from catheters to AVF experienced decreased CRP levels after six months.

The investigators also looked at the association between vascular access type and inflammation in 39 pediatric patients. Children with catheters had significantly elevated concentrations of the pro-inflammatory cytokine IL-6 compared with children who had AVF or AVG. 

“Children comprise an important cohort for study, since they do not generally suffer from confounding co-morbidities such as diabetes, smoking or longstanding atherosclerosis,” Dr. Goldstein said.

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