United Network for Organ Sharing (UNOS) is a non-profit, charitable organization that serves as the nation’s transplant system, known as the Organ Procurement and Transplantation Network (OPTN), under contract with the federal government. UNOS continuously evaluates new advances and research and adapts these into new policies to best serve patients waiting for transplants.

The current kidney matching system has helped tens of thousands of people in the United States get successful kidney transplants each year.  

New possibilities 

But there are ways the system can be further improved. Some kidney recipients have not received a kidney that works as long as they may need. In addition, some patients have waited much longer than others for a kidney due to their blood type or their immune response to most available kidneys.

An improved kidney matching system will take effect in late 2014. It is a result of years of review and consensus-building among transplant professionals and people who have personal experience with donation and transplantation. Their primary goal was to make the system better without making major changes to the parts of the system that work well.

The new system should help more people have longer function with their transplanted kidney. It should also shorten the wait for some groups of people who often wait a very long time because they are hard to match with most kidneys.

Many people will not see any major change. The time spent waiting for a kidney is still a major factor in matching. Transplant candidates will not lose credit for any time already spent waiting. Patients who began dialysis before being listed for a transplant will have their waiting time backdated to their first dialysis date.

Improved efficiency

People who will need a kidney for the longest time will be matched more often with kidneys that have the longest expected function. Kidneys that may last a shorter time will be more readily available for people who have difficulty remaining on dialysis.

Some patients are hard to match with most kidney offers because they have uncommon blood types. Others are likely to have an immune system rejection for most kidneys. The new system will seek to boost their chances of getting a matching offer.

"The new system will give immune sensitized candidates more priority for kidneys they aren’t likely to reject."

People with blood type B often wait longer for a kidney than people with other blood types, in part because it is harder to find a donor with type B blood. Donors with blood type A generally can’t donate to a person with blood type B. However, some blood type A donors have a “subtype” that allows them to match a type B candidate. The new system will give first priority to these donor kidneys for type B patients. Since blood type A donors are more common than blood type B donors, more offers now should be available for type B candidates.

In other cases, people have developed immune system responses that make it very hard to find a kidney their body won’t reject. This may happen because of having a previous transplant or blood transfusion, or even from pregnancy. People who are “highly sensitized” often wait five or more years before receiving even one match offer.

The new system will give immune sensitized candidates more priority for kidneys they aren’t likely to reject. People who have a slightly higher sensitivity will get slightly more priority than they would have under the previous system. People who are very highly sensitized will get much more priority.