Early Experience with New Kidney Allocation System

A Perspective from the Organ Procurement Agency

The United Network for Organ Sharing Kidney Allocation System was implemented in December of 2014 after more than a decade of planning, modeling, analysis, debate, and public comment. The goals of the Kidney Allocation System included making better use of available kidneys, increasing transplant opportunities for difficult to match patients, increasing fairness by awarding waiting time points on the basis of dialysis start date, and having a minimal effect on most candidates.

Although the changes made in 2014 addressed an important set of issues, the problems of kidney discards and low utilization remain. The magnitude of the issue is highlighted by comparing the current United States discard rate of >20% with the EuroTransplant discard rate of <10% (¹,²). At a recent National Kidney Foundation consensus conference, transplant leaders from across the country along with representatives from the Health Resources Service Administration, the Centers for Medicare and Medicaid Services, the United Network for Organ Sharing, the Scientific Registry for Transplant Recipients, the Association of Organ Procurement Organizations, and the public met to discuss the kidney discard problem and take action to remedy this loss of the precious gift of donation. The group identified several areas for improvement: (1) Improved patient education to increase acceptance of marginal kidney offers; (2) Regulatory changes to encourage kidney utilization; (3) Transplant program improvements to manage offers and improve acceptance rates; (4) Financial incentives to offset increased costs associated with marginal kidney transplants; and (5) Allocation changes to minimize cold ischemia time.

The new Kidney Allocation System has been successful in many ways. The time has come to apply the same thoughtful process to the allocation and utilization of marginal kidneys to honor the donors and their families, while saving more lives.

Results of Kidney Allocation System

There has been a substantial increase in transplants for highly sensitized patients (calculated panel reactive antibody of 99%–100%). There has also been an increase in transplants for kidney candidates with >10 years of dialysis. Longevity matching has improved as well, better aligning the expected lifespan of the recipient with the expected survival of the graft. In the 2 years since implementation, 56% of candidates with the greatest estimated post-transplant survival (top quintile) received kidneys from donors with a kidney donor profile index of <20% (top quintile). Access to high-quality kidneys for prior living kidney donors has not changed significantly, and this group of candidates continues to be well served (³). Finally, transplant rates have remained virtually the same across all ethnicity groups. Clearly, the Kidney Allocation System has achieved its goals of increasing equity and utility (¹,⁴).

Opportunity for Increased Utilization

The Kidney Allocation System was not designed to and did not positively affect kidney utilization. In fact, the kidney discard rate, calculated by dividing total kidneys transplanted into total kidneys recovered, is trending upward and now hovers around 20% overall. The discard rate for donation after circulatory death donor kidneys has increased by 4% points compared with the preimplementation rate (¹).

Since 2010, nearly 15,000 deceased donor kidneys have been recovered but ultimately, have not been transplanted. Clearly, not all of these kidneys were suitable for transplant, but it is estimated that at least one third of them would have provided survival benefit and improved quality of life for the right candidate (⁵). This translates into roughly 800–1000 missed opportunities for kidney transplantation per year. Considering that the EuroTransplant discard rate is one half that of the United States, the number of useful kidneys discarded may be even higher. These hard to place kidneys include but are not limited to high kidney donor profile index kidneys (above 85%); kidneys from donors at increased risk for transmission of HIV, hepatitis C virus, or hepatitis B virus; and kidneys from donors with AKI.

Revisions to Improve Utilization

The main focus of the new system has been to ensure fairness for patients awaiting transplantation, an important and noble goal. Unfortunately, the inefficiency of the current allocation system in allocation of the hard to place kidneys adds extended cold ischemic time, which often becomes the final strike against them, resulting in unnecessary kidney wastage.

We have an excellent model that can serve as a starting point for a new paradigm in allocation in the United States. EuroTransplant has developed an efficient system for minimizing kidney wastage that includes the Recipient Oriented Extended Allocation system and the EuroTransplant Senior Program. The first system converts the allocation process from patient centered to program centered after a finite number of offers are declined, resulting in placement of kidneys that would otherwise likely be discarded. This is activated when a kidney is declined by five separate transplant programs for medical reasons. In addition, this system can be used when there are logistic challenges placing the kidney at risk of wastage. In this setting, multiple centers are contacted and have 30 minutes to select up to two candidates on the match list, and then, the highest-ranking patient is identified as the recipient. In the report by Vinkers et al. (²), rescue allocation was used for 665 donors (16.4% of all donors). If the system fails to identify a recipient, there is a safety net known as competitive rescue allocation. Competitive offers are made to at least three centers in the region or country. The organ is then sent to the center that accepts the offer first. In rare cases with great risk of direct loss of the organ, EuroTransplant will apply the competitive rescue allocation immediately (⁶).

A process similar to Recipient Oriented Extended Allocation has been used successfully in at least one donation service area in the United States (K.C., unpublished observations). For at-risk kidneys, each transplant program in the donation service area can submit two patients with no donor-specific antigens to a crossmatch tray (the Targeted List). The kidneys are then offered to patients according to their ranking on the national waitlist. All centers agree to officially code out all other candidates to allow for quick decision making. The organ procurement organization can then begin national offers on an expedited basis. In the first 5 months of 2017, the Targeted List was used 32 times, with 25 kidneys being placed locally to this patient population.

The EuroTransplant Senior Program allocation concept seeks to match appropriate organs to unsensitized recipients in the older population. This allocation program treats older patients and kidneys from older deceased donors as a separate subsystem. Patients over the age of 65 years old receive offers for these extended criteria organs on a priority basis. Allocation time is significantly shortened, and acceptance by the patient population is increased.

These programs serve as proof of concept that an alternative fast track pathway for kidneys at objective risk of wastage can increase utilization.

The recent large increase in deceased organ donation is encouraging, but the gap between candidates awaiting transplant and the number of patients transplanted persists. Transplant programs and organ procurement organizations need an alternative allocation pathway to take full advantage of the increasing supply of deceased donor kidneys to best serve the growing population of candidates awaiting kidney transplantation.

Summary

As noted above, there are numerous barriers to improving utilization, but there is cause for optimism. Regulators have recently recognized the need for revisions to transplant outcome metrics to encourage greater utilization. The Center for Medicare and Medicaid Services increased the tolerance limit for flagging transplant programs from 150% to 185% of the expected 1-year graft and patient survival (⁷). The United Network for Organ Sharing Membership and Professional Standards Committee has implemented a change in program monitoring, whereby a program that fails the 1-year survival test for all of its kidney transplants will not be flagged if its outcomes are within parameters when kidney transplants from donors with a kidney donor profile index >85% are excluded. This mitigates the concern that using these kidneys will potentially harm a program. It remains to be seen if these changes in the flagging thresholds will translate into increased utilization of these kidneys. The Health Resources Service Administration–sponsored Collaborative Innovation and Improvement Network project is allowing the sharing of best practices across the country and encouraging programs to increase their use of kidneys with a kidney donor profile index >50%. Events, like the National Kidney Foundation conference referenced above, are resulting in new ideas for further regulatory reform, increased patient education, and program practice changes. These changes and efforts will be helpful, but revision of the Kidney Allocation System to enable an alternative allocation pathway and reduce cold ischemic time of kidneys at risk of discard is essential to improving utilization.

Our system of transplant is built entirely on the altruistic gift of donation made by donors and their families who make the decision to donate, because they want someone to benefit from their tragedy and want to have a new ending written to their loved one’s life story. We, as a transplant community, make an implicit promise to them to honor the most precious gift that they will ever give and use that gift for its highest value. We can and must do better.

Disclosures

None.