Significant Reduction in Waitlist Mortality for Lung Transplants Following New Allocation Guidelines

Recent research has revealed a noteworthy decline in the number of deaths among patients awaiting lung transplants, attributed to the newly implemented allocation system by the United Network for Organ Sharing (UNOS). The changes, introduced two years ago, prioritize medical urgency in the distribution of donor lungs.

According to findings presented at the 2025 ATS International Conference and published in the American Journal of Respiratory and Critical Care Medicine, the outcomes for patients on the waiting list have significantly improved since the introduction of the Composite Allocation Score (CAS). This new scoring system assesses various factors, including the urgency of the patient's medical condition, to determine the allocation of donor organs.

The research indicates that the risk of death or removal from the waiting list has decreased markedly under the CAS framework. The most critically ill patients have experienced the most substantial benefits from these changes. Historically, lung transplants were allocated based primarily on geographical proximity, with local patients receiving priority. However, following a 2017 lawsuit, UNOS expanded the allocation radius, leading to the development of the current guidelines.

Prior to the implementation of the CAS in 2023, data showed that 11.2% of patients died or were delisted while waiting for a transplant. After expanding the geographical area in 2017, this figure slightly improved to 8.4%. The introduction of the CAS, however, resulted in a remarkable further reduction to 4.1%.

For patients with the highest urgency scores--representing the top 5% of those waiting--the figures were even more striking. These individuals were three times more likely to succumb to their conditions prior to the CAS implementation compared to the current system.

Experts express optimism regarding the results, noting that the emphasis on medical urgency and other relevant factors logically leads to better outcomes for patients in critical need. Advocates emphasize the importance of healthcare providers ensuring that the medical urgency of their patients is accurately represented in their CAS scores, as the data shows tangible benefits for these individuals.

Future research is planned to delve deeper into the specifics of the study, particularly examining how certain biological factors considered within the CAS may correlate with improved outcomes for critically ill patients.