A new study in JAMA Pediatrics says the United Network on Organ Sharing (UNOS), which allocates donated organs across the country, may inadvertently give adults an advantage over children when it comes to liver transplants, KJZZ.com reports. 

The study looks at current criteria UNOS uses to prioritize patients on organ waiting lists. Currently, both children and adults are ranked on similar 40-point scoring systems that evaluate their short-term risk of death—the Model for End-Stage Liver Disease (MELD) score for candidates ages 12 and older and the Pediatric End-Stage Liver Disease (PELD) score for those ages 11 and younger. 

However, the study says setting a child’s PELD score against an adult’s MELD score may not be fair, suggesting that the formula for children underestimates their risk of mortality by up to 17 percent.

“The trouble is, when there’s a tie between an adult and a child, the scores say, ’Oh, they have the same risk of death.’ But, in fact, the child has a much higher risk of death,” said study coauthor Mark Roberts, MD, of the University of Pittsburgh.

This latest research confirms the worries first presented in a 2017 study that described a five-year period in which 316 children died or were removed from transplant lists, while 1,667 adults received transplants from children. Despite an adequate supply of donated child livers to meet the need of children awaiting transplants, those livers often go to adults instead.

Moving forward, doctors want to investigate new ways to help close the disparity in organ availability between old and young people.