Old formula gave more weight to time spent on waiting list
New rules for allocating donor kidneys have led to more transplants for blacks and Hispanics, whose access to donor organs had been held artificially low under an earlier formula.
A recent study also identified other “winners and losers” under the new system: Younger adults gained more access to needed organs, compared with those who are still “over-represented” on recipient lists—adults over 50 and those whose immune systems more readily tend to reject donor organs.
The rule changes did nothing to increase the number of minorities on transplant waiting lists, the researchers emphasize.
“The new allocation policy only addresses the population of patients on the waiting list,” said study leader Dorry L. Segev, associate professor of surgery at Johns Hopkins University School of Medicine. “There are still profound disparities for non-Caucasian candidates.
In December 2014, the United Network for Organ Sharing instituted what researchers described as “the most significant change to the kidney allocation algorithm” in more than 20 years.
The old algorithm was “first-come, first-served.” It assigned organs—with some exceptions—based largely on how long patients had been on the waiting list. Now, more weight is given to time spent on dialysis than time spent on the list.
The change was meant to increase transplant access for members of racial and ethnic minorities, who often aren’t placed on the waiting list in a timely manner after dialysis starts, Segev said.
For the study, published in the Journal of the American Society of Nephrology, researchers compared transplants from nearly two years before the new rules kicked in to nearly 10 months after.
During this short time, deceased donor transplant rates jumped 19 percent for black recipients and 13 percent for Hispanics. In 20,692 transplants in the 23 months before the new system, black patients received 31.7 percent and Hispanic patients received 16.9 percent. After 8,481 transplants in 10 months under the new system, black patients received 37.2 percent and Hispanic patients received 18.4 percent.
Others benefiting from the new rules include adults between 18 and 50. Under “first-come, first-served,” Segev said, donor organs predicted to last for many years were often transplanted into patients not expected to live as long, and organs predicted to have a short life span were often given to patients expected to live a long time.
Under the new rules, which match organs and patients partly on likely longevity, the transplantation rate increased by 47 percent for candidates ages 18 to 40 and by 17 percent for candidates ages 41 to 50.
Conversely, the transplantation rate declined by 7 percent for those between 51 and 60, 10 percent for those between 61 and 70, and 24 percent for those older than 70.
Winners under the new algorithm also include patients with elevated levels of certain “reactive” antibodies, a measure of immune system sensitivity designed to predict what proportion of deceased donor kidneys are likely to be accepted or rejected in the body of a patient.
The study shows that the proportion of very highly sensitized patients—who can accept organs from less than 1 percent of the population—initially spiked from 2 percent of those receiving deceased donor kidney transplants in the old system to about 12 percent soon after the new rules were implemented, then fell by August 2015 to 7 percent. That percentage, which represented 61 of 857 transplants that month, still unfairly “overrepresents” such patients in the total candidate pool, Segev said.
Thus, although the new rules fix some of the problems researchers had highlighted under the old algorithm, issues still need to be addressed before the system is fair and can lead to the best outcomes for patients, particularly minorities, Segev said.
According to the Organ Procurement and Transplant Network, run by UNOS, more than 100,000 patients in the United States are currently on the kidney transplant waiting list, and 3,000 are added each month. About 12 people die each day waiting for a donor kidney.