Time for a Change: The New Kidney Allocation System
In this blog post, Rich Formica discusses the factors that led to the design and implementation of the new kidney allocation system and highlights some of the major changes that the system introduces. He also makes it clear that this is not the end of changes to how kidneys will ultimately be allocated and distributed. Those who have followed the discussion of changes to the liver allocation system will recognize that consideration of broader geographic sharing of kidneys is also on the horizon. As these conversations progress, we must keep in mind the goals of any proposed changes, which are to increase the equity of kidney transplantation as well as the efficiency of organ donation. We can all best advocate for patients with end-stage organ failure by being truly informed about the issues.
Time for a Change: The New Kidney Allocation System
Richard Formica, MD, Yale University School of Medicine - AST Board Member, Chair of the OPTN/UNOS Kidney Transplantation Committee
On December 4 of this year, a new kidney allocation system (KAS) will go into effect.1 This is the final product of over 10 years of work and compromise by many generations of OPTN/UNOS Kidney Transplantation Committees. Although not perfect, KAS represents a significant first step towards improving kidney allocation in this country and provides a strong footing from which to tackle the larger issue of geographic disparity in access to kidney transplantation.
The current system was not conceived as a unified allocation policy. When kidney transplantation began it was only offered to younger patients with minimal underlying comorbidities. Because all potential candidates looked more or less “the same,” time spent waiting for a transplant was a reasonable proxy for need. Over time, as immunosuppression and patient management improved and the criteria for kidney transplantation became more inclusive, transplantation became the gold standard for treating end stage renal failure. With this development, the number of patients waiting for a kidney transplant swelled. In response to the increasing demand for organs, donor service areas (DSA) and UNOS regions began to modify the allocation system, through the incorporation policy variances, largely in an effort to address what was perceived as local problems with organ availability. The result was an allocation system that placed an overemphasis on waiting time, progressively downplayed biologic and immunologic considerations, failed to adapt to the changing needs of the patients being listed, and morphed into an overlapping patchwork of variances that rendered the implementation of any meaningful changes nearly impossible from an information technology perspective.
On December 4, the system reboots and begins anew. With the start of the KAS all existing variances, other than the two incorporated into the new system (credit for time on dialysis prior to registration and A2 /A2B donor kidneys allocated to eligible blood group B recipients), will be retired. Going forward, kidney allocation will be done in a manner that is standardized, logical and uniformly applied across the country. Additionally, there are meaningful improvements for patients. In the new system, patients receive waiting time credit for time spent on dialysis prior to listing. This moves kidney allocation towards a need-based approach because time on dialysis is a major factor effecting survival, both pre- and post-transplant.2 Patients with longer estimated post-transplant survival (lower EPTS score) will be prioritized to receive donor organs with longer anticipated function (lower KDPI), beginning the practice of longevity matching in kidney allocation. Highly sensitized patients will now receive waiting points that more accurately reflect the difficulty they have in receiving organ offers. Patients who have CPRA of 98, 99 and 100% will have elevated access to kidneys from geographic areas beyond their DSA, such that if a compatible kidney becomes available, they can receive such offers – which may be their only chance – as soon as they are listed. Additionally, those kidneys most likely to be discarded will be distributed to a broader geographic area in order to increase the odds of quickly finding a suitable patient at a willing transplant center.
However, as important as these and the many other improvements contained in the KAS are, there is a more fundamental change that may not be readily appreciated. The new KAS both takes initial steps to promote wider geographic sharing of kidneys and was designed to be adaptable to broader geographic units of organ distribution, a possibility the committee has begun investigating. The implementation of the new KAS corrects the arbitrary and inefficient nature of kidney allocation that has evolved over time and prepares a new baseline with which to compare potential future policies designed to reduce geographic disparity in access to kidney transplantation.
2Meier-Kriesche HU, Kaplan B. Waiting time on dialysis as the strongest modifiable risk factor for renal transplant outcomes: A paired donor kidney analysis. Transplantation 2002;74:1377-81.