Study suggests U.S. heart transplant list is failing sick kids

The U.S. heart transplant list for children isn't accurately ranking the sickest kids highest, making it more likely they may die while waiting for a donor heart, a new study claims.

Some very sick children were categorized as category 2, the lowest of the three categories of urgency on the list, while others who were not as sick had a 1A "most urgent" status, researchers found.

As a result, a less sick child was sometimes offered a donor heart that might have gone to a child nearer death, results showed.

"The current system is not doing a good job of capturing medical urgency, which is one of its explicit goals," said researcher Kurt Sweat , a graduate student in economics at Stanford University.

For the study, researchers analyzed data from all 12,408 children younger than 12 listed for heart transplants between January 1999 and June 2023 in the United States.

The team compared kids' actual ranking on the wait list with how they would have been ranked if their listing was based on medical urgency.

"From the perspective of economics, we think about this fundamentally as an allocation problem," Sweat said in a university news release. "We've got this scarce resource of donor hearts, and we want to make sure they're going to candidates who can get the most usage from them."

"In the case of pediatric heart transplantation, with such high wait-list mortality, what that usually looks like is you want to prioritize patients who are sicker," Sweat added.

But kids' placement on the wait list often is flawed, in that those most in need aren't always at the top of the list, researchers discovered.

The current wait list ranks children based on what type of heart problem they have and the medications they are receiving, researchers said.

By applying a broader range of medical factors that better reflect the urgency of a transplant -- like kidney or liver function, or whether a child is malnourished -- researchers found that some sicker kids were being overlooked by the wait list.

Researchers also found that the three wait-list categories -- 1A, 1B and 2 -- are so broad that less sick kids were sometimes offered a heart before sicker kids within the same category simply because they'd been waiting longer.

Over the decades, kids' risk of dying on the heart wait list fell from 21% to 13%, and the total number of heart transplants increased, researchers found.

However, three wait list revisions that took place to improve the program's effectiveness had no actual impact on the decline in deaths, researchers found.

Instead, the death rate declined because of medical advances like mechanical pumps that support a child's heart while waiting for transplant, researchers said.

Doctors also have gotten better at recognizing when a kid should be listed for transplant, which means children tend to be healthier at the time they're offered a donor heart than they were in the past. For example, they're less likely to be supported by a ventilator or receiving kidney dialysis.

"Wait-list mortality has declined, which is a very good thing, but based on our analysis, it doesn't look like the allocation changes made the difference," said senior study author Dr. Christopher Almond , a professor of pediatrics at Stanford University. "Although the intent behind the current system is to prioritize the children based on medical urgency, we saw that the system is not actually sequencing patients according to their risk."

Adding nuance to the wait-list system by accounting for more health factors could reduce children's risk of dying before they get a new heart, researchers concluded.

The findings were published Monday in the Journal of the American College of Cardiology.

A new revision to the wait list is underway, based on new allocation systems drawn up for other organs like lungs, researchers said. A proposal for the heart list is expected to be ready for review next year.

"Wait-list mortality, which is the chance that a child will die while awaiting transplant, is higher in pediatric heart transplant than for virtually any other organ or age group," Almond said. "It is really complicated to figure out how to do this well, but it appears there is still room for improvement."

More information

The Children's Hospital of Philadelphia has more on the pediatric heart transplant list .

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