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Questions and answers for transplant candidates about the kidney allocation system

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Welcome to our question and answer page for kidney allocation.

Below is commonly requested information about kidney allocation. We hope you find it helpful.

If you have other questions or comments, contact the Organ Procurement and Transplantation Network (OPTN) Patient Services line at (888) 894-6361 or submit them here.

How are kidneys classified?

Every kidney offered for a transplant has a Kidney Donor Profile Index (KDPI) score. The score ranges from zero to 100. The KDPI estimates how long the kidney will work compared to other kidneys. A KDPI score of 20 means that the kidney will work longer than 80 percent of all other kidneys. A KDPI score of 60 means that the kidney will work longer than 40 percent of all other kidneys. Learn more about KDPI with this animated video.

What goes into a KDPI score?

The following facts about the donor go into the KDPI score:

  • Age
  • Height
  • Weight
  • Ethnicity
  • Type or method of death (heart stoppage or brain death)
  • Stroke as cause of death
  • History of high blood pressure
  • History of diabetes
  • Exposure to the hepatitis C virus
  • Serum creatinine (a measure of kidney function)

How are transplant candidates classified?

Each kidney candidate gets an individual Estimated Post-Transplant Survival (EPTS) score. The score ranges from zero to 100. EPTS estimates how long each candidate may benefit if he or she gets a kidney transplant, when compared with all other people listed for a kidney transplant.

A person with an EPTS score of 20 is likely to survive with a transplanted kidney longer than 80 percent of other candidates. Someone with an EPTS score of 60 will likely need a kidney longer than 40 percent of other people. Your transplant team can tell you what your EPTS score is. Learn more about EPTS with this animated video.

What goes into an EPTS score?

The following facts about the candidate go into the EPTS score:

  • Age
  • Length of time spent on dialysis
  • Having received a previous transplant (of any organ)
  • Current diagnosis of diabetes

How does the system use KDPI and EPTS scores to match kidneys?

Kidneys that are expected to last the very longest—those with a KDPI score of 20 or less—are first offered to patients likely to need a transplant the longest – those with an EPTS of 20 or less. If a kidney with a KDPI of 20 percent or less is not accepted for any of these patients, it is then offered to any other person who would match, regardless of their EPTS score.

Kidneys with high KDPI scores will work for a shorter time than others. They can help candidates who are not able to be on dialysis for a long time.

Your transplant team can discuss with you the best options for you based on your EPTS score.

How does the system match organs to pediatric patients?

Pediatric patients are younger than age 18. They risk having growth and developmental issues if they must wait a long time for a transplant. For this reason, they receive priority for 35 percent of kidneys that are likely to work the longest – kidneys with a KDPI score of 35 percent or lower.

How does the system help hard-to-match patients?

It is hard to find a kidney match for some candidates for many reasons. They may have a rare blood type. Others may have an immune system that rejects most kidneys. The system works hard to boost their chances of getting a matching offer.

Blood type considerations

People with blood type B often wait longer for a kidney than people with other blood types. It is harder to find a donor with type B blood.

Donors with blood type A generally cannot donate to a person with blood type B. Blood type A donors are more common than blood type B donors. But, some blood type A donors have a “subtype” that allows them to match a type B candidate. The system gives first priority for these donor kidneys for type B patients who may match. Doing this can increase access to transplant for type B patients.

Immune system considerations

Some people have developed immune system responses that make it very hard to find a kidney their body will not reject. This may happen because of having a prior transplant or a blood transfusion, or even from pregnancy. People who have exceptionally high antibody levels that react to foreign tissue, also called “highly sensitized,” often wait five or more years before receiving even one kidney offer.

The system gives immune sensitized candidates higher priority for kidneys they are not likely to reject. The amount of priority increases along with the level of immune system sensitivity. People who have a slightly higher sensitivity get slightly more priority. People who are very highly sensitized (98 percent or above) get much more priority.

Your transplant team can tell you whether you are sensitized. If you are, they will discuss the extra priority you would receive.

How does the system calculate waiting time?

A transplant program may evaluate and list you for a transplant even before you start dialysis. You will receive additional priority for waiting time when you either start dialysis or have kidney failure (a creatinine clearance below 20 ml/min). If you are listed early, you can be matched for deceased donor kidneys based on medical matching criteria in the kidney allocation policy.

What if I am not listed for a transplant but want to be?

Talk to your doctor about your current health and your treatment options. The best time to start a transplant workup is either at the time you begin dialysis, or very close to when you need to start dialysis. This will allow you to be considered as early as possible for a kidney offer.

For more information

Start with your doctor or the medical team at your transplant hospital. They know the most about your medical condition and treatment. Do not be afraid to ask questions. Your medical team will help you to understand all your treatment options.

The toll-free OPTN Patient Services line (888-894-6361) can let you know about the kidney allocation system and other resources available to you. Additional information is available online on the following websites:

Acronyms and terms

Creatinine Clearance – A test that helps determine whether the kidneys are functioning normally. Creatinine is produced from the metabolism of protein as when muscles burn energy.

Dialysis – The clinical purification of blood as a substitute for the normal function of the kidney.

EPTS – An Estimated Post Transplant Survival score is assigned to all adult candidates on the kidney waitlist.

KDPI – The Kidney Donor Profile Index is a numerical measure that combines 10 donor factors to summarize into a single number the quality of deceased donor kidneys relative to other recovered kidneys. The KDPI is derived by first calculating the Kidney Donor Risk Index (KDRI) for a deceased donor.