So I was browsing my twitter feed yesterday and saw this from @okarol
One perspective on the proposed changes to how the distribute kidneys fb.me/100dAwkxiThen I saw almost the exact same message was on my Facebook feed from The Kidney Group:
— Karol Franks (@okarol) November 12, 2012
|Twitter's most followed Kidney Practice: the kidney group should be ashamed of this post.|
To understand what is driving the desire to change the current system and to understand how the proposed system is superior, one needs to understand the shortcomings of the current way organs are distributed.
First, unlike hearts or livers, people can live for years on dialysis waiting for a transplant. This is why we have 75,000 people on the kidney transplant list. Tragically, only 16,843 were transplanted in 2010.
|Look at the 15,000 people listed for |
the second or third time (USRDS)
Currently the most common reason for a kidney transplant to fail is death with a functioning graft. On the one hand, death with a functioning graft is an ideal outcome, this is how the vast majority of people without kidney disease die, i.e. they die with a kidney still capable of supporting life. But in the world of kidney transplant, death with a functioning graft is a measure of inefficiency. We live in a world with a vast undersupply of organs and not only are there not enough organs to go around, but an increasingly common reason for patients to be listed for a transplant is re-listing after their first transplant failed. If all of these patients had been matched to a kidney that better lined up with their life-expectency they would not be getting back in, an already overcrowded, line.
|Over time total graft failure and return to dialysis/transplant has fallen but death with a functional graft has remained flat. Better graft matching could mean more people living with transplants. (USRDS)|
Michigan no longer uses that system for calculating wait-time. In Michigan, the clock starts the first day of dialysis. So a dialysis patient that takes three years to finally find his way to a transplant center and get listed would get credit for three years of wait time as soon as he was approved for transplant. This largely neutralizes any discrimination he would have suffered from being randomized to a bone-head nephrologist or living in a racist medical system. This is a smart change and it is used by the proposed transplant allocation system.
The current system is over 25 years old and suffers from limited medical knowledge available at the time it was created. The current system looks at factors that affect graft survival (HLA matching) but ignores factors associated with recipient survival (diabetes, age, etc).
We grade patients antibody levels (PRA) on a continuous scale from 1 to 100. Patients with higher levels have more difficulty finding matches. In order to help these patients with additional burdens in finding a match they are awarded points. Unfortunately the current system awards a fixed value if the level is over 80 and does not appreciate the continuous nature of this factor. The proposed system treats this as the continuous value it is.
Currently, there are a lot of discarded kidneys that could be used to benefit patients but the current system ranks kidneys as Standard Criteria or Extended Criteria. A system that recognized that not all recipients need 20 years of renal function would allow more of these marginal kidneys to be used.
It is interesting that Laine Ross's article does not address any of the weaknesses of the current system. The reader is left with the impression that the current system is fine except for a vague mention of "inefficiencies." She does not elaborate on what inefficiencies means but, make no mistake, it means we can get more people living with a transplant by changing how we allocate the organs. The new system plans on doing that, so if you agree with Laine you are arguing for less people living with a transplant.
The centerpiece of the proposed system is a system that ranks both recipients and the kidneys. The top 20% of candidates (by estimated years of life remaining) are matched to the top 20% of kidneys. Getting young people high quality kidneys that will last decades makes sense to me but apparently ethicists from the University of Chicago feel that putting 20 year old kidneys in 68 year old diabetics is a good use of a scarce resource. By giving young people long lasting kidneys we can avoid these patients losing their kidneys and getting re-listed. This will help reduce the total wait list.
The rank list also works on the bottom end of the scale, acceptable but marginal kidneys at the bottom of the scale, the worst 15%, are made available to patients on a voluntary basis. Older patients and patients who are failing dialysis can be desperate for a kidney. This is intended to expand the project that began with extended criteria donors and reduce the number of viable kidneys that are wasted.
Outside of the top 20% and the bottom 15% the system does not change. This new allocation is really just a revision to update and fix some weaknesses with the current system.
Ross calls out the 20% rule because it can not magically determine the exact time of death of everyone in the queue for a transplant. Seems like a pretty high bar to cross. The system that is proposed has a c-statistic of 0.72, which is where she get's her:
...their model will get it right about 75 percent of the time.The system is just as accurate as the system used to determine life expectancy for liver transplants and does a very good job of preventing the primary problem of putting kidneys with a short life expectancy in patients with a long life expectancy. The system does not need to be perfect to be better than the current system which is totally blind to this important issue. Interestingly, the Kidney Committee, looked at a better system to predict life-expectancy but it was so complex that people were suspicious. They settled on the current system because it is simple and does a good enough job. I agree that transparency is an important quality in any system that will be distributing kidneys.
Reading the whole article it looks like a hit-peice trying to score ethical points while lives hangs in the balance. This is the third attempt to revise the transplant allocation program. Ethicists have repeatedly deep six-ed previous attempts and while we try to find the perfect system we are trapped in a system that everyone agrees has significant ethical lapses and wastes both kidneys and years of transplant viability.
Update: The Kidney Group has removed the link to the article from their Facebook page. @okarol has blocked me on Twitter. No peep from U.S. News and World Report. This post made it to the RenalWEB homepage.