The timing of arteriovenous fistula placement and medicare costs during dialysis initiation.

Abstract

Although considered a rare disease in 1972 when its treatment was added to the Medicare program, the incidence and prevalence of total kidney failure, called End Stage Renal Disease (ESRD), has grown substantially in the last half-century. There are now over 500,000 patients with ESRD, comprising about 1% of all Medicare patients but accounting for over 6% of total expenditures. There were over 110,000 incident ESRD patients in 2006, projected to grow to over 150,000 by the year 2020, with a total of almost 800,000 ESRD patients by that time (Gilbertson, 2005; USRDS, 2008, Vol 2, Fig 2.1). Although kidney transplants have become more common, organ shortages as well as the complex disease burden of patients result in the majority of patients having their ESRD treated by clinic-provided hemodialysis (HD). This process, which represents the type of renal replacement therapy for 90% of new ESRD patients, involves pumping a patient's blood through an external dialysis machine to filter and clean the blood before returning it to the body. This process requires a vascular access be placed in the patient to allow the blood to flow from the patient to the dialysis machine and back again. There are two main types of vascular access: a temporary catheter, which is simply a plastic tube inserted through the skin and into a vein, and an internal access, which connects an artery and vein together to produce a strong location from which blood can be drawn. The internal access is called an arteriovenous fistula (AVF) if the vein and artery are joined directly together. If they are joined with a synthetic tube it is called an arteriovenous graft (AVG). Catheters are quick to insert, cost very little and can be used almost immediately. However, they are prone to infections and complications like clotting. AVFs and AVGs, on the other hand, are surgically created, causing them to be more expensive and require time to mature before they can be used. However, since they are completely internal they are much less at risk for infections and complications. For those who are good candidates for an AVF, the timing of their AVF placement in relation to dialysis initiation can be classified into three distinct groups: (i) those who have had an AVF placed early enough so that it is mature and ready for use when it is time to begin chronic dialysis; (ii) those who have had an AVF placed prior to dialysis initiation that has not had enough time to mature, forcing them to begin dialysis using temporary catheters until the AVF is ready; and (iii) those who do not have an AVF placed until after they have already begun regular dialysis, resulting in the full maturation time occurring while they dialyze with catheters. The main research question I wish to address is: Does having a mature AVF at the start of dialysis result in a net cost-savings to Medicare compared to either: having an AVF in place but not yet mature at initiation, or having an AVF placed soon after the start of dialysis? Currently, Medicare makes a few exceptions regarding coverage of ESRD patients for those not already Medicare eligible. While Medicare does not have any exceptions involving AVF placement prior to dialysis, if doing do would actually result in lower overall costs it might benefit Medicare to make such an exception.