The United Network for Organ Sharing, UNOS, the non-profit organization responsible for allocating donor organs to patients waiting for transplantation, is proposing a new system to determine how kidneys are distributed.* If approved during a vote in the spring of 2013, this proposal will represent the first major overhaul of the national kidney allocation system in 25 years.
According to Lloyd E. Ratner, MD, MPH, Chief of Kidney and Pancreas Transplantation at NYP/Columbia and a former member of the kidney transplantation committee working to revamp the UNOS rules, the current system works predominantly on a first-come, first-served basis. Although that seems reasonable on the surface, and the system was designed to be as fair as possible, unintended consequences have cropped up during the past three decades – such as the fact that a number of donor kidneys end up being discarded every year.
Dr. Ratner explains more in the following interview.
Q: Why has the system for allocating kidneys remained unchanged, when the rules governing livers, hearts, lungs, etc, have been updated as organ transplantation has become more prevalent?
Dr. Ratner: For the other vital organs, allocation is based on severity of the patient’s illness. Someone in dire need of a heart or liver will be prioritized higher than someone who can wait longer for a transplant, because you can’t live without a heart or liver (although LVADs are now changing that for many patients with heart failure). With kidney failure, dialysis is considered a viable alternative to transplantation. In other words, you can live without a kidney for a while, where you can’t do without those other organs.
Q: According to the New York Times article published September 19, 2012, nearly 18% of donor kidneys are discarded each year, and about one fifth of those go unused because a recipient can not be located in time. How will the proposed changes attempt to reduce the number of donor kidneys that are discarded each year?
Dr. Ratner: Those numbers are somewhat variable, depending on how one counts, but experts do agree that a number of some donor kidneys are wasted. Some are discarded because they are deemed less than optimal, while others are discarded because too much time elapses while trying to find a match, and the organ will no longer function.
To address the first issue, it is helpful to understand that when a donor organ becomes available, it is not like getting a brand new one from the factory, like you’d get with a pacemaker or hip replacement. Like a used car, some kidneys have more mileage, some have been better maintained than others, some have a higher risk of problems like transmitting infectious diseases, etc. All of those factors get assessed, and in the current system, if the kidney is deemed unsafe, meaning it won’t function long enough or well enough, it will be discarded. In some cases, a kidney may be less than optimal, but it still could be a great option for someone who is on dialysis or whose life expectancy is not very long for one reason or another. At our center, we have instituted ‘extended-criteria’ protocols that allow use of selected organs that do not meet the strictest criteria, but are determined to be acceptable — and our outcomes still remain excellent. As a result, many more patients receive transplants here than at other hospitals, and their time on the waitlist is far shorter than at other centers. But in the absence of extended-criteria protocols, many kidneys do get discarded each year that could possibly be used.
According to the new rules, kidneys that are likely to function the longest will be preferentially allocated to people with the greatest chance of living the longest, while kidneys that are likely to last a shorter time will be given to people with a shorter life expectancy and who can’t afford to remain on the waitlist.
The issue of geography is another complicated factor. The way the current system is designed, a donor kidney is first offered to the local hospital. If the local center declines the organ, it can then be offered to a wider region, and if it still remains available, then it will be offered to hospitals across the country. The national centers often treat the most ill patients who are in the greatest need of a transplant, but ironically, the longer that kidney sits while centers make their determinations, the less chance the kidney will reach the patients in those centers who need it most. With each passing hour, its functionality decreases. This is a very important issue, and the new proposal does not significantly address this.
Q: What other issues are you considering while trying to develop the new rules?
Dr. Ratner: The ramifications of the current system are complex. Although its original intention was to provide as absolutely fair a system as possible to those on the waitlist, in practice, the reality of it is turns out to be quite complicated. For instance, the way that transplant programs are evaluated has the unintended effect of causing centers to decline organs in order to earn better grades.
Here is how that happens. The performance of transplant centers, which is very carefully monitored by the Scientific Registry of Transplant Recipients, gets graded on post-transplant outcomes. If outcomes fall below a certain level, the program can get penalized or even shut down. If a program is highly selective about which donor organs it will accept, and thereby declines more organs and performs fewer transplants, then the program may earn higher grades as far as its outcomes – but more of its patients remain on the waitlist and die in the process. If programs really want to take care of their patients, they need to be able to transplant as many as possible. That means taking some risk, i.e. considering extended-criteria organs, for instance. But the current system rewards risk-averse behavior. I believe the system needs to evaluate both pre-transplant and post-transplant care when grading centers’ outcomes. The clock should start when a person is listed for transplantation. If that were to be put in place, there might be slightly worse kidney survival outcomes post-transplant, but far more people would be alive in the end.
Q: Will the new system provide better matches of kidneys to patients, something like the way the system in Germany roughly matches the age of a kidney with the age of the recipient?
Dr. Ratner: The rationale behind the proposed change will attempt to match the life of donor organs with the life expectancy of patients. Kidneys can not be allocated based on the age of the patient due to age discrimination laws in this country, but other factors will be used to estimate the expected life of the organ. That way, if a kidney is expected to function for 50 years, it can be given to a younger person who is expected to have a long life, while a kidney with less functionality can be given to someone whose life expectancy is five years.
*UNOS is responsible for allocation of deceased-donor organs; patients who receive a living donor kidney, who are not on a waitlist for a deceased-donor organ, are not part of the following discussion.