Timing of Arteriovenous Fistula Placement: Keeping It in Perspective

Timing, they say, is everything. When to swing at the baseball’s pitch, when to depart to catch an airplane, when to sell (or buy) a stock: act too early or too late and the results may be unsatisfactory. So, it seems, may be the case for placement of an arteriovenous fistula for hemodialysis. Place it too late and it may not be ready to use for hemodialysis, place it too early and it may develop complications or never be needed. However, if the timing is not right (as is so often the case), does it matter whether we are early or late? For baseball and stocks, maybe not, but this distinction is consequential for a plane trip and an arteriovenous fistula.

According to the most recent data from the US Renal Data System, more than 115,000 patients a year in the United States reach ESRD and need RRT.¹ A select few will be fortunate enough to get a pre-emptive kidney transplant, and some will choose peritoneal dialysis, but >90% start hemodialysis and join the slowly expanding population of about 400,000 patients on hemodialysis in the United States. Each of these hemodialysis patients needs a vascular access: an arteriovenous fistula, an arteriovenous graft, or a central venous catheter. A fistula is the preferred hemodialysis access. Once established, it is associated with the longest access survival, lowest cost, and fewest interventions, as well as the best patient survival, of all the choices for hemodialysis access.² However, up to 60% of new fistulas may be unsuitable for hemodialysis³ and require radiologic or surgical interventions to achieve suitability, engendering cost, failed attempts at cannulation, extra clinic visits, and increased reliance on catheters for hemodialysis. These struggles with creating a usable fistula are magnified in the elderly and patients with severe cardiovascular disease, raising questions in the literature on the best choice of access for these patients and about the optimal timing for placement of a fistula to maximize its chances of being ready for use upon initiation of dialysis.

In this issue of JASN, Hod et al. examine the optimal timing of incident fistula placement in an elderly population.⁴ Specifically, they explored the relationship between when a fistula was placed before the start of hemodialysis and its subsequent use at hemodialysis initiation in a retrospective cohort of 17,511 patients from the US Renal Data System dataset. The patients were 67 years of age or older and had their first fistula placed from 2005 to 2008. Overall, 55% of the cohort initiated hemodialysis with a fistula. The success rate was significantly higher for men, whites, and patients with longer predialysis nephrology care; the success rate was poorer for patients with diabetes and congestive heart failure (CHF). After stratification by time of fistula creation before hemodialysis initiation, the odds ratio (OR) for successful fistula use improved steadily for up to 6–9 months, after which the OR remained stable at around 1.0. The cumulative number of access procedures per patient also rose steadily the longer the fistula was placed before hemodialysis initiation and leveled off after 6–9 months. However, in contrast to the fistula success rate, the cumulative number of procedures did continue to increase after 12 months without a corresponding improvement in fistula success. This suggests that these extra procedures were needed to maintain fistula patency before initiation of hemodialysis. Earlier fistula placement, more than a year prior to hemodialysis initiation, was associated with a slight increase in the OR for fistula success for women and blacks as well as patients without diabetes or CHF. In contrast, patients with diabetes or CHF may experience more complications and have a slightly lower OR for fistula usability when the fistula is placed more than a year before hemodialysis initiation.

On the basis of this information, if dialysis initiation were scheduled like an airplane departure, we would want to book our flight 6–9 months in advance. However, it is hard enough to plan a trip 6–9 months in the future, let alone know the timing of hemodialysis initiation in that time frame. Even when the patient is being monitored by a nephrologist, the rate of progression from CKD to ESRD may not be constant, and the need for hemodialysis may be precipitated by random, stochastic unexpected clinical events leading to a sudden drop in renal function. Moreover, the relationship between measures of renal function and the development of clinical symptoms requiring hemodialysis varies between patients.

So if we are liable to be wrong about the exact timing of hemodialysis initiation, should we be early or late? The risks incurred by “early” and “late” fistula placement are not equal. Delaying placement of a fistula risks starting hemodialysis with a catheter and all its substantial complications and costs,⁵ while early fistula placement incurs a rather modest increase in cumulative access procedures (or perhaps the patient will never need the fistula at all). In a broader perspective, only 16% of patients in the United States currently start hemodialysis with a fistula, while >80% of patients start with a catheter.¹ The major health imperative in this population is trying to increase fistula use and reduce the number of catheters needed at dialysis initiation. Waiting for the optimal time for fistula placement risks increasing the number of patients who start hemodialysis with a catheter. The article by Hod et al., however, does sharply remind us that our primary focus should be on developing ways to speed and increase fistula maturation so that most fistulas are ready for hemodialysis within 1–2 months after surgical creation rather than having to wait for 6–9 months.

But that is the future, and we have to make plans for today. So should we be early or late? Ideally, we’d like to be able to schedule the flight (fistula placement) at the last minute and still catch the plane, but until that time comes, I prefer to err on the side of being early rather than miss the plane altogether by being late.

Disclosures

B.D. reports receiving consulting fees from Proteon therapeutics, Novita Therapeutics and Shire Regenerative Medicine, stock in Flow Forward LLC and Metactive LLC and grant support from Proteon Therapeutics, Reata Pharmaceuticals and AbbVie Inc.