Lung transplant waitlist deaths drop under new composite allocation system

Editor's Note

Implementation of the Composite Allocation Score (CAS) in lung transplantation significantly reduced the proportion of patients who died or were removed from the waitlist, including those with the most urgent medical need, according to a June 17 article in Healio. The findings were presented at the American Thoracic Society International Conference.

As detailed in the article, researchers conducted a retrospective cohort study using data from 24,368 patients listed for lung transplant in the United Network for Organ Sharing (UNOS) registry since February 2015. Led by Mary Raddawi, MD, and colleagues at Columbia University Irving Medical Center, the study examined outcomes before and after major policy changes: the expansion of the donor allocation radius in November 2017 and the implementation of the CAS in March 2023.

The outlet reports that the CAS is based on nine factors, with the most weight assigned to candidate medical urgency, the likelihood of at least five-year survival, and age younger than 18 years at listing. Researchers found that the proportion of patients who died or were delisted was highest before November 2017 at 11.2%, declined to 8.4% between November 2017 and March 2023, and was lowest during the CAS period (March 2023 to March 2024) at 4.1%.

According to the article, the same trend was observed in a subgroup of 1,239 patients with the top 5% of urgency scores at listing. Death or delisting occurred in 34.6% of these patients before November 2017, 22.2% between November 2017 and March 2023, and 6.5% during CAS implementation.

Statistical comparisons confirmed these changes were significant. The subdistribution hazard ratio (sHR) for death or delisting before November 2017 compared to the CAS period was 3.32 (95% CI, 2.74–4.02), while the sHR for the 2017–2023 period compared to CAS was 2.1 (95% CI, 1.75–2.52), Healio reports

For high-risk subgroups, the elevated risk persisted, the outlet reports. Patients in the top 5% urgency group had an sHR of 7.97 (95% CI, 3.72–17.1) before November 2017 and 4.8 (95% CI, 2.29–10.15) between 2017 and 2023, compared to the CAS period. For the 3,413 patients using high-flow nasal cannula at listing, the sHR was 7.68 (95% CI, 5.54–10.54) before 2017 and 5.28 (95% CI, 3.92–7.12) between 2017 and 2023.