The Pros and Cons of Interventional Nephrology

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Interventional nephrology programs can improve arteriovenous fi stula placement rates.
Interventional nephrology programs can improve arteriovenous fi stula placement rates.

Vascular access (VA), commonly proclaimed both as the “lifeline” and the “Achilles heel” for patients on hemodialysis (HD), has been an unsettling though modifiable issue for both patients and providers. The most common VA complications are stenosis, infection, and thrombosis. It is well established that the mechanical and infectious complications of VA adversely affect patient outcomes.1

Furthermore, end-stage renal disease (ESRD) cost Medicare approximately $24 billion in 2007, almost 6% of Medicare's total expenditure for almost 1% of its beneficiaries.2 A significant proportion of these costs were incurred by VA-related complications, which also account for a significant proportion of hospitalizations in patients with ESRD. The cost of VA care per patient per year historically has been around $8,000-$10,000, nearly 25% of total ESRD medical costs. The ESRD population is experiencing significant growth.

Today, more than 340,000 patients are on HD in the United States, making the issues related to VA ever more challenging.2 The importance of VA in influencing patient outcomes is further reflected in development of VA guidelines by the Kidney Disease Outcomes Quality Initiative and the creation of the Fistula First Breakthrough Initiative. 3, 4, 5 An effective and expeditious process for care of VA, however, has remained illusive so far.

The ability to diagnose and treat patients with kidney disease requires a comprehensive approach that necessitates use of special techniques, including the diagnosis of urinary tract obstruction by ultrasonography, performance of kidney biopsy to diagnose the cause of proteinuria or glomerular hematuria, placement of a peritoneal dialysis (PD) catheter, and maintenance of VA for HD.

These unique aspects of nephrology care are not only quite technical, difficult, and intriguing, they are challenging for a general nephrologist. Traditionally, specialists other than nephrologists have rendered these procedural aspects of nephrology care. While that is indeed an arrangement of convenience, it creates multiple layers of care with a complex array of somewhat disconnected providers with a potential to bewilder the patient, break the chain of communication, and cause delay in care.

Sometimes, when such a procedure does not yield anticipated results, questions about ownership and responsibility for the care of ESRD patients also arise.

Frustrations with historically fragmented and inadequate care of VA during the last decade of 20th century resulted in an uprising of “interventional” nephrologists with a mission to address these issues 6, 7. This rather small but highly motivated group of physicians went outside the box to address inconsistencies in the care of the procedural aspects of nephrology despite very tough and sometimes extreme resistance from the traditional stakeholders in these techniques.

The American Society of Diagnostic and Interventional Nephrology (ASDIN) came into existence at the beginning of the 21st century. This special branch of nephrology, known as interventional nephrology (IN), has now become prevalent with an irresistible but healthy momentum.

The practice of IN has been under close scrutiny both from within and from outside the field since its inception. IN's foundation in the private practice environment and its practice mostly outside the hospitals led to initial concerns about sufficient training and standards of quality. These concerns were dispelled quickly by the publication of meticulously recorded data by IN pioneers. Nevertheless, it is only prudent to examine the pros and cons of any novel approach.

PROS

The advantages of IN are clear to those involved in the care of VA and can be summarized as follows:

  1. Expeditious care: The most frustrating aspect of VA care has been the delay in rectification of AV access dysfunction or failure as prompt treatment of VA complications is essential to saving the life of the afflicted patient. This is indeed the reason that necessitated the development of IN. It is all too common for patients with dysfunctional VA not to receive an early appointment for intervention and later to be rescheduled due to other “more important” and glamorous procedures taking precedence. This results in missed dialysis treatments, medical management of complications, and placement of temporary lines for emergent dialysis. Yet another day of being “nothing by mouth” for the rescheduled procedure only perpetuates the prevalent malnutrition of HD patient. This is not the case when IN services are available. Most access issues can be dealt on the same day or within 24 hours. ESRD patients now become the focus of attention, medical care improves, and patient satisfaction increases.
  1. Patient/operator familiarity: Dialysis patients have myriad issues that simply are beyond the scope of other specialists interacting with them. Assessing and arranging emergent dialysis, correction of acid-base and electrolyte balance, proper drug dosaging, and follow up of access outcome after the procedure are not issues that other specialists can be expected to be concerned with. In contrast, for a nephrologist doing these procedures, it is only a logical sequence of actions. For the patient, it is immensely reassuring to see a familiar operator, improving rapport and satisfaction.
  1. Seamless communication: Medical errors are common and result in harm. 8 Breach in communication and improper hands-off procedure is a common cause of medical errors. When IN is involved in care of VA, there is a natural transfer of information to other partners in care of the patient. For example, when I operate on a patient, I call the dialysis unit, discuss the outcome of the procedure, and suggest any special precautions in using the access with the nurse. I am also able to advise possible strategies during dialysis. In addition, if I observe any other medical problems that need attention, I automatically indicate that to the team. Other specialists cannot provide these aspects of care.
  1. Achieving superior outcomes: Patterns of VA utilization are remarkably different, with variations evident not only across continents, but also within a network, region, city, or even within a practice. A number of studies have shown the impact of type of VA on outcomes of the patients. 9, 10 The ability of the nephrologist to influence the decision-making regarding VA placement and maintenance is intricately related to better outcomes. There are numerous examples, including from our own practice, where initiation of an IN program resulted in significant improvement in incident and prevalent arteriovenous fistula (AVF) rates. There is no doubt that a collaborative approach through routine vascular access conferences involving an access coordinator, a surgeon, and a nephrologist lead to an in-depth consideration of the best possible VA for an individual patient, allowing a personalized approach. Use of IN services allows access planning without delay. Vascular mapping or venography can be performed as indicated, avoiding VA “catastrophes” that may result from an inappropriate access placement. For example, a careful approach can avoid access placement in the extremity complicated by steal phenomenon or central vein occlusion. Furthermore, training of fellows in such a program results in producing more “access-conscious” nephrologists, resulting in less utilization of temporary lines for dialysis and improved evidence based management of access related complications.

Evidence from the recent literature has indeed shown better VA outcomes after initiation of IN programs. Between 1995 and 2002, establishment of a VA center decreased number of hospitalizations and missed VA related outpatient dialysis treatments.11

Similarly, hospitalizations were reduced over a two-year period in a study in Alabama, with improved patient satisfaction and possible decrease in the cost of VA care.12 Another recent report indicated similar outcomes.13

Additionally, there appears to be an economic advantage of such an approach that may be related to the decrease in the cost of procedures done as an outpatient compared to an inpatient setting.14

  1. Prospective approach to planning of future VA: Planning of dialysis access must take into account patients' medical history, access history, and potential next access, including consideration of a PD catheter placement. These aspects can often get ignored in the midst of concurrent illnesses in a busy practice. Having an IN program to consider all such approaches leads to a personalized approach to VA. This is exemplified by cases involving a secondary AVF in a patient who previously experienced access failure or placement of PD catheter in a suitable patient when VA is not optimal and has a poor chance of success.
  1. Opportunity for innovation and research: IN is one of the newest innovations in caring for the kidney disease patient. Even though VA has been used since the mid 1960s, organized research in VA has occurred only recently. A plethora of important questions related to VA remain unanswered, such as how to predict and improve maturation of an AVF, how to prevent failure of AV access and design personalized access configurations associated with most suitable flow dynamics, and how to decrease mechanical and infectious complications of catheter-based access. We have yet to elucidate the pathophysiology of neo-intimal hyperplasia, which is the single most important cause of VA failure. There has been significant progress related to these problems during the last decade, with greater involvement of academic interventional programs. We can hope to have answers to some of these questions in near future.15-18 Newer VA technologies are likely to improve the processes of VA creation and maintenance as a result of these innovations.

CONS

Although the advantages of IN are obvious, it is necessary to consider potential disadvantages and dilemmas of such a “hands-on” approach of IN. The considerations are as follows:

  1. Limited workforce: There are approximately 7,000 nephrologists in the United States. Looking at rapidly expanding ESRD population, a nephrology workforce study (co-sponsored by the American Society of Nephrology, National Kidney Foundation, Renal Physicians Association, American Society of Pediatric Nephrology, and the American Society of Transplant Physicians) predicted a severe shortage of nephrologists to meet future patient care demands due to lack of adequate number of trainees and retirement of existing nephrologists. This raises the concern whether we have enough nephrologists to take care of the rising number of patients on dialysis. While this is a genuine concern, it is expected that the interventionalist would still serve as a practicing nephrologist, akin to the interventional cardiologist. By improving the VA care, a reduction in the number of hospitalizations could free enough time to at least neutralize the time spent in performing the procedures.

  1. Limited training opportunities: IN is an emerging area of “super specialization.” Pioneering nephrologists learned the techniques from interventional radiologists and surgeons and had limited resources that were mostly within private practice arena. Even today, the opportunities for such training are rather limited, although they are expanding (ASDIN Web site lists some of those opportunities at www.asdin.org). The new skills of ultrasound training and PD catheter placement are also becoming routine.19 We hope that with the emergence of more academic programs, there will be adequate number of opportunities for training of younger nephrologists. Currently, there is no subspecialty recognition of IN by the American Board of Internal Medicine due to the small number of such specialists. As the number of IN professionals increases, it will remain a possibility. The training is of crucial importance and criteria for credentialing have also been proposed.20
  1. Interventional “turf” issues: Ever since the development of IN, there have been political issues related to the ‘control' of nephrology patient. Other interventionalists often see the interventional nephrologist as someone encroaching in their specialty. Often, the initiation of IN programs becomes a divisive and polarizing event for the nephrologists, interventional radiologists, and surgeons. However, it is more than obvious that, sparing a handful of practices, those specialists are largely incapable of meeting the demands of providing expeditious and compassionate care to ESRD patients. Nephrologists, being the most proximate provider, are the most reasonable provider of all aspects of ESRD patient care, including access intervention. It has been the experience of most programs, including ours, that the introduction of IN has not reduced the workload of other specialists. In most cases, it has improved their willingness to take care of VA issues more expeditiously due to a perceived “competition.” Thus, turf issues are, in fact, stimulants of the quality of IN. In other situations, it has provided other specialists an opportunity to focus their expertise and enthusiasm on more challenging areas in their field. However, a multidisciplinary and collaborative approach will be needed to advance this field.21
  1. Quality control: As IN is an evolving science, the most important challenge is developing criteria for excellence. At present, there are only a limited number of studies describing the safety of procedures done by IN. One particular study describing over 14,000 procedures by IN showed a success rate of 96% and complication rate of 3%-4%. 22 High success rates and low complication rates were also indicated in another study.12 Compared with radiologists, nephrologists performing kidney biopsies were similarly effective. 23 To ensure the quality of the procedures performed by nephrologists, ASDIN issued a position statement about the complications of HD VA procedures in 2008.24 Additionally, ASDIN recently launched a voluntary registry to track the outcomes of the procedures done by IN to develop a benchmark. 25 These efforts have to continue to maintain or improve the quality of these procedures.

Conclusion

The development of IN remains a work in progress, but it is clear that IN is not just a concept, but a reality. With the use of traditional endovascular therapy and evolving pharmacologic and biologic approaches, IN has the potential to change the spectrum of ESRD care for the better. In addition, the use of PD may increase as the care of PD access by IN becomes more prevalent.26 A few nephrologists have started creating AVFs, and that may encourage other nephrologists to do the same. IN will no doubt lead to the emergence of a superior model of care for VA resulting in improved outcomes. It is the right thing to do for our patients.

Dr. Agarwal is Professor of Medicine and Director of Interventional Nephrology at Ohio State University in Columbus.

References

  1. Dhingra RK, Young EW, Hulbert-Shearon TE, et al. Type of vascular access and mortality in U.S. hemodialysis patients. Kidney Int . 2001;60:1443-1451.
  2. United States Renal Data System: USRDS 2009 Annual Data Report: Atlas of chronic kidney disease and end stage renal disease in the United States. Bethesda, MD. National Institute of Diabetes and Digestive and Kidney Diseases.
  3. NKF-DOQI Clinical Guidelines for Vascular Access. New York: National Kidney Foundation, 1997
  4. National Kidney Foundation K/DOQI clinical practice guidelines in vascular access: 2006 update. Am J Kidney Dis. 2006;48:s176-s306.
  5. http://fistulafirst.org/AboutAVFistulaFirst/History.aspx, accessed October 11, 2010.
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  8. To Err Is Human: Building a Safer Health System. Kohn L, Corrigan J, Donaldson M, eds. Washington, DC: Committee on Quality of Health Care in America, Institute of Medicine. National Academies Press; 2000
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  15. Dixon BS. Why don't fistulas mature? Kidney Int. 2006;70:1413–1422.
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  17. Krishnamoorthy MK, Banerjee RK, Wang Y, et al. Hemodynamic wall shear stress profiles influence the magnitude and pattern of stenosis in a pig AV fistula. Kidney Int. 2008;74:1410-1419.
  18. Budu-Grajdeanu P, Schugart RC, Friedman A, et al. A mathematical model of venous neointimal hyperplasia formation. Theor Biol Med Model. 2008;5:2-9.
  19. O'Neill WC. Sonography of the kidney and urinary tract. Semin Nephrol. 2002;22:242-253.
  20. Saad TF. Training, certification, and reimbursement for nephrology procedures. Semin Nephrol. 2002;22:276–285.
  21. Allon M, Bailey R, Ballard R, et al. A multidisciplinary approach to hemodialysis access: prospective evaluation. Kidney Int. 1998;53:473–479.
  22. Beathard GA, Litchfield T. Effectiveness and safety of dialysis vascular access procedures performed by interventional nephrologist. Kidney Int. 2004;66:1622-1632.
  23. Gupta RK, Balogun RA. Native renal biopsies: Complications and glomerular yield between radiologists and nephroloigsts. J Nephrol. 2005;18:553-558.
  24. Vesely TM, Beathard G, Ash S, et al. Classification of complications associated with hemodialysis vascular access procedures: A position statement from the American Society of Diagnostic and Interventional Nephrology. J Vasc Access. 2008;9:12-19.
  25. http://asdin.org/displaycommon.cfm?an=1&subarticlenbr=129.Accessed October 11, 2010.
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