Today marks an exciting change in kidney transplantation. Although there have been adjustments to the kidney allocation system over the last 20 years, there has not been a major change. This is despite a growing waitlist and a shortage of organs. Allocation is currently driven predominantly by wait time rather than matching kidneys with appropriate recipients. As a result, young patients with a long life expectancy may be transplanted with kidneys with a short life expectancy, requiring them to eventually rejoin the waitlist for a second transplant. At the same time, patients with a shorter life expectancy may receive kidneys with a long life expectancy, resulting in patients dying without full utilization of the organ. This has resulted in re-transplantation being the third most common cause for waitlist registrations after diabetes and hypertensive nephrosclerosis. In addition, there are populations, including ethnic minorities and biologically disadvantaged patients, who wait significantly longer for a kidney transplant.
A new kidney allocation system, which was first proposed in 2012, takes effect today. This system does not correct every problem of the prior allocation system but is a good start. Below is what I consider the major implications of the new system. For a complete review of the changes, please visit the OPTN website.
First, the new allocation system will improve access to transplantation across minorities that have delayed referral to transplant centers. Numerous studies reveal race and socioeconomic status to be barriers to accessing the transplant list. The new allocation system will grant wait time from the initiation of dialysis in an effort to reduce this barrier. Biologically disadvantaged patients with blood type B or pre-existing HLA antibodies will also benefit. Blood type B patients will be able to receive kidneys from blood type A2 donor and sensitized patients will receive a sliding scale of points starting from a PRA of 20%. Highly sensitized patients with cPRA > 98% will also receive priority on both a local and national level.
Second, longevity matching, or pairing kidneys expected to last the longest with people expected to live the longest, will maximize the benefit of these lifesaving organs. When patients expected to live the longest are matched with the highest quality kidneys, they may not require re-transplantation, which in turn may slow the growth of the waitlist and leave organs for others in need. Longevity matching requires the use of two scores, the EPTS (patient estimated post-transplant survival) and the KDPI (kidney donor profile index), which each range from 1-100%. These scores are counterintuitive as the lower scores predict better patient and kidney survival. It is important to realize that this will occur only for healthiest 20% of patients as determined by EPTS, and the top 20% quality kidneys as determined by KDPI. The majority of patients will not be negatively impacted by this change.
Third, the new allocation system strives to improve sharing of kidneys throughout the country. There is a great disparity of wait time in different parts of the country. Because of this disparity, regions (such as region 9 [NY]) often import kidneys that would otherwise be discarded. Improved sharing will occur for lower quality kidneys (KDPI >85%), sensitized patients, and HLA-matched kidney. This will also be done without the penalty of a payback system. Such a change can reduce discards of valuable organs and improve organ access to people in regions expected to wait the longest.
As with every major policy change, there will be challenges and opportunities for improvement. However, overall, the new allocation system appears to be a much needed change in strategy and a step in the right direction.
Dr. Vinay Nair
AJKD Blog Advisory Board member