Vascular access choices in end-stage renal disease (ESRD) patients depend on a number of factors. A recent update was published in AJKD from the US DOPPS Practice Monitor with international comparisons. Corresponding author Dr Ronald Pisoni (RP) discusses this paper with Dr. Sean Kalloo (AJKDblog), AJKD Blog Contributor.
AJKDblog: Despite significant improvement in vascular access use for prevalent hemodialysis patients in the United States over the past 17 years, there has been no improvement in vascular access use for new hemodialysis starts, with nearly 80% initiating hemodialysis therapy with a central venous catheter (CVC). What are some of the factors involved with such a high rate of CVC use in the US?
RP: The Fistula First program recently transitioned to the Fistula First Catheter Last initiative to focus on the development of tools and resources to help dialysis facilities and clinicians reduce catheters and increase AV fistula rates in hemodialysis patients. The crux of this latter initiative is that, overall, poorer clinical outcomes are seen for HD patients dialyzing with a central venous catheter compared with an arteriovenous vascular access (fistula or a graft). The main focus of this effort is to minimize exposure of patients to a catheter during their time on HD. It has been indicated that in some patients it is difficult to create a functional AVF, with the patient having to experience many access-related procedures in an attempt to create a functioning AVF. Thus, a better approach may be to optimize AV access use according to a patient’s characteristics – placing an AV graft in patients for whom it is unlikely that an AVF will be successful. Although studied considerably, questions still remain regarding the individual patient characteristics and surgical/interventional/dialysis unit practices that best predict the type of AV vascular access that will yield the longest time of use with the fewest associated procedures for an individual patient, while minimizing the number of “catheter use” days. To inform these decisions, there is a great need for additional large, well-designed studies to investigate many other aspects of vascular access care and practice that have not been captured in the past. These kind of studies will be vital for making it clear to care-givers and patients what access type may be most suitable for a particular patient, and provide a more individualized approach towards related benefits and risks.
In the short term, however, the Hemodialysis Fistula Maturation Study, based upon ~600 US HD patients, is being looked towards for providing new insights regarding factors important for AVF maturation. The Kidney Health Initiative’s (KHI) Vascular Access Committee is currently working on several white papers in defining key outcome measures for clinical endpoints regarding various aspects of vascular access use and function. In addition, the various vascular access-related QIP measures can be expected to incentivize further improvements in vascular access care in the near future – especially for further increasing AVF use and for decreasing continuous catheter use of more than 90 days. Unfortunately, current QIP measures for dialysis units do not address catheter use at the time of HD initiation for new ESRD patients as this aspect of care is not completely under the control of dialysis units – in particular for patients receiving CKD care in clinics not associated with the dialysis unit or who have not received CKD care prior to ESRD.
AJKDblog: How does the US compare to our international counterparts with respect to vascular access management?
RP: As shown in our recent AJKD paper, some countries display high AVF use (87-92% in China, Japan, and Russia; 80-83% in Turkey, Germany, UK, and Australia/New Zealand) and one question is whether this is achievable in the US, and should this even be a goal? From prior work in the DOPPS, we have seen that AVF survival is considerably shorter in North America than in Europe or Japan. Furthermore, the blood flow rates in the US (median: 400 mL/min, IQR: 399-450 mL/min) are much higher than those used in Japan (median: 200 mL/min) or in Europe (median: 300 mL/min). Within continental regions, we have seen that AVF survival is lower in facilities using higher blood flow rates. Given the widespread use of higher blood flow rates in US and higher AVF failure rates, there may be a lower likelihood to achieve very high AVF prevalence in the US. Furthermore, comorbidity profiles differ to varying degrees across countries, which can impact successful AVF use. However, some of the best evidence of what is achievable in the US are dialysis units which have routinely achieved ≥80% AVF use rates in recent years (DOPPS, unpublished findings), and the lessons which can be learned from these centers. Further improvements in interventional/surgical vascular access care, development of new technologies for improving AV access maturation or patency, and improved AV access monitoring can be expected to further enhance vascular access use.
AJKDblog: Are there certain steps that the nephrology community should be taking to ensure appropriate care of vascular access in our patients?
RP: One large area to focus improvements in US vascular access use is to greatly reduce the percentage of new patients initiating hemodialysis with a catheter. A key point, as shown in this AJKD paper, is that even though large improvements have been seen in vascular access use among prevalent HD patients in the US during the last 12 years, there has been no improvement in access use at the time of dialysis initiation, with ~80% initiating HD with a central venous catheter. In prior studies from the DOPPS (see Pisoni et al 2002 & Rayner et al) and other research groups, we see that AVF survival is shorter in patients having had prior catheter use. Furthermore, patient preference for a catheter is greater if currently using or having previously used a catheter, even though clinical outcomes are poorer for patients using a catheter (see Fissel et al & Pisoni et al 2009). Thus, by reducing initial catheter use, it may help to decrease patient preference for a catheter as well as improve the longevity of the first AVF used.
AJKDblog: Can we incentivize AVF use in nephrology practices?
Recently, Allon et al proposed that the current US reimbursement system is a major factor underlying the continued poor level of access use for US incident patients. Our present study indicates that most patients even with prior nephrology care still initiate hemodialysis with a central venous catheter. Allon et al recommended changes to Medicare reimbursement to incentivize AV access use through: (1) earlier disbursement of Medicare benefits to uninsured patients requiring fistula placement, and (2) changing the current physician and hospital reimbursement for fistula placement to incentivize either AV access placement and/or achieve a mature functioning fistula in new hemodialysis patients. These authors argue that such a change likely could yield a substantial cost savings of $500 million dollars per year (Allon et al). Thus, improvements in access use in incident ESRD patients could be beneficial both for patient outcomes through decreased exposure to catheters and for payers/providers through reduced overall costs.