Following implementation of a new scoring system for patients needing a lung transplant, people on the waiting list in the United States are less likely to die or leave the list while waiting for a new organ.
In 2017, a young woman named Miriam Holman who needed a lung transplant filed a lawsuit arguing that the policy of allocating available lungs was unfair as it prioritized geographic location over medical urgency. Before this time, donor lungs were first offered to local candidate recipients, even if sicker people were on the list who were outside the local area.
After this case, the authorities broadened the allocation area to 250 nautical miles and began to design a new scoring system known as the Composite Allocation Score (CAS), which was actioned nationwide in the United States in 2023.
The lung CAS gives potential recipients a score based on nine different attributes including factors such as severity of their condition and likelihood of survival without a transplant, blood and HLA typing, age and height and travel efficiency, a measure of how easy it would be for them to get to the transplant hospital in time.
The current study, which was presented at the 2025 American Thoracic Society International Conference, assessed the impact of the changes in 2017 and the impact of the CAS on patients needing lung transplants in a group of 24,368 patients.
The patient outcomes analysis showed that before the changes in 2017, 11.2% of patients on the waiting list died or were delisted. This figure dropped to 8.4% after the changes in 2017 and then even further to 4.1% after the CAS was instituted.
The researchers also carried out an analysis just looking at the sickest 5% of patients to assess the outcome for them. They found that pre-2017, 34.5% of these patients died compared with 22.2% after the 2017 changes and 6.5% after the CAS scoring system began.
“We always want to make sure that any time we make a change to the allocation system that we’re improving outcomes, especially for our sickest patients,” said lead study investigator Mary Raddawi, a researcher at Columbia University Irving Medical Center in New York, in a press statement. “This provides confirmation that we’re on the right track.”
Overall, the CAS scoring system reduced the risk of death or delisting by more than 3-fold compared with the pre-2017 system and more than 8-fold for the sickest patients.
“When you think about the fact that now we’re focusing on many different factors, including medical urgency, it makes sense that the waitlist mortality would go down for our sicker patients—but it is nice to see the actual numbers,” said Raddawi.
