NATIONAL HARBOR, MD—Patients who dialyze with an arteriovenous fistula (AVF) have better outcomes, including decreased mortality rates, compared with patients who use other modes of vascular access. After successful surgery and maturation, AV fistulas have the lowest rates of thrombosis, infections, and interventions to maintain patency—leading to cost savings—as well as the highest rate of long-term patency.
Given these benefits, the Fistula First Breakthrough Initiative (FFBI) made it a goal to increase the rate of fistula use in prevalent US patients to 66%. However, fistulas don't always work, and even when they do, the process can demand much time and effort.
These considerations have fueled controversy over whether Fistula First is the right route to achieving optimal vascular access. In presentations here at the National Kidney Foundation 2012 Spring Clinical Meetings, two experts on the topic took opposing sides of the debate.
In terms of outcomes that matter, fistulas offer the best option for hemodialysis vascular access, said Jay Wish, MD, Professor of Medicine at Case Western Reserve University School of Medicine and Medical Director of the Dialysis Program at University Hospitals Case Medical Center, in his presentation.
“AVF is appropriate in a large majority of HD [hemodialysis] patients, with the goal that the AVF will succeed as patients' primary access,” he said.
Achieving a functional fistula can be a challenge, he acknowledged, and not every patient should get this access type, including those without suitable blood vessels and perhaps some patients with a limited long-term prognosis.
However, the Fistula First goal is not 100% but 66%—a benchmark that has already been reached in other countries. As such, it is not unrealistic, Dr. Wish added.
“In the United States, facilities with more than 66% AVF increased from 6.2% in 2007 to 33.6% in December of 2011,” he said. “This is a phenomenal increase, and it represents the cooperative effort. Now we have one-third of the United States achieving the goal.”
Dr. Wish also worked to dispel the belief that since fistulas require more time and multiple procedures to function, Fistula First was associated with an increase in the catheter rate between 2003 and 2011.
“Because of the awareness of getting rid of catheters, you are seeing people getting access much sooner,” he said. “As a result, the catheter rate has decreased.”
A number of factors determine the type of vascular access an individual gets and, by extension, these overall rates.
“Whether or not a patient has a fistula or a catheter is not only a function of the patient but also the culture within dialysis facilities and nephrology practices,” Dr. Wish said.
“You have some facilities where nephrologists are lazy and don't take the responsibility of referring their patients to vascular access; you have facilities that don't have vascular access coordinators to steer patients through evaluation. There is a lower rate of fistulas and grafts and a higher rate of catheters because of this.”
The conclusion that fistulas are better than grafts can only be made if a particular outcome is ignored, said Michael Allon, MD, Professor of Medicine in the Division of Nephrology at the University of Alabama at Birmingham, who argued the “Fistula First: To Fail (To Be Used for Hemodialysis)” side of the debate.
“While fistulas certainly last longer, data presented does not include fistulas that do not mature, which is like a surgeon not including everyone who died on the table,” Dr. Allon said.
According to recent studies, the primary fistula failure rate is around 60%, while the graft failure rate is only around 10% to 20%, he noted. Fistulas take months to be ready for use, while grafts take weeks.
While waiting for fistulas to mature, patients are dependent on catheters—a problem given the relationship between long-term catheter use and infectious complications, hospitalizations, lower dialysis adequacy, mortality, and costs.
“The choice between fistula and graft should depend in part on potential for failure,” Dr. Allon said. “You should also look at the likelihood of catheter bacteremia, expected patient survival, and outcome of previous fistula.”
Although older age, female gender, and black race have been shown to correlate with the likelihood of primary fistula failure, the decision on vascular access comes down to the individual patient.
“If you have a 20-year-old patient with no chance of bacteremia who hasn't started dialysis yet and has several years left of his life, of course the patient should get a fistula.
“But for patients with several comorbidities and not many years left, this may ultimately not be a good idea. For example, a 75-year-old woman with diabetes, already on a catheter, coronary artery disease, stroke, likelihood of non-maturing fistula and bacteremia is high, expected patient survival one to two years—of course this patient should get a graft. The fistula won't work, and you are going to muck around for months trying to fix it. Meanwhile, the patient will have bacteremia, and before you have something worth using, the patient will be dead.”
The Vascular Access Decision: Dealing with Uncertainty
Choice of hemodialysis vascular access is complicated by a lack of evidence on how best to treat the individual patient.
“If you ask a surgeon or a nephrologist what the criteria are that indicate a patient is eligible for a fistula, there is really nothing uniform out there that has been defined and validated,” said Charmaine Lok, MD, MSc, Cochair of the Fistula First debate session and of the National Kidney Foundation 2012 Spring Clinical Meetings Program Committee, in a phone interview after the conference.
“That's why it is so important for the studies that are currently ongoing, such as the NIH [National Institutes of Health] fistula maturation study, to take these factors into account and try to determine which fistulas will fail and, therefore, which patients are eligible for a fistula,” said Dr. Lok, who is Associate Professor at the University of Toronto and Medical Director of the Chronic Kidney Disease and Hemodialysis Vascular Access Programs at the Toronto General Hospital.
Alfred Cheung, MD, of the University of Utah School of Medicine, chaired the session with Dr. Lok.
A number of influences should be taken into account when choosing a vascular access type.
“I don't think it is just the patient characteristics,” Dr. Lok said. “I think it's the patient clinical characteristics, their vessel characteristics, their life circumstances, facility practice patterns, and surgical factors, including who the surgeon is and surgical history.”
When the optimal vascular access method is not clear-cut, patient education and communication are especially key.
“I think in these marginal patients we need to be up-front with them and tell them that we are going to try a fistula because if it works it will be the best access for them, but there is a chance that it won't, and that we will need to do procedures that may be uncomfortable to help the fistula to work,” Dr. Lok said.
She expressed agreement with both sides of the debate.
“Fistula is definitely the first to succeed in a patient who is eligible for a fistula, and there is no question that if we can get a fistula to function it is the best access, and we should really try to have the fistula as our number one goal for those patients who are eligible.
“Then for the gray area, my personal advice is still to try the fistula but to give all the education and advice to the patient on what to expect just in case it doesn't work so the patient will still go back for another access and not depend on a catheter, so the fistula is first to fail in the patient where it is not appropriate.
“I agree with both of them, and I think in many of the areas they are saying the same thing, but the key message that Dr. Allon was trying to emphasize of one size does not fit all is really important, and I think we lose sight of that sometimes.”