Early Analysis of the Composite Allocation Score for Lung Transplantation on Race-Based Outcomes

The United Network for Organ Sharing recently transitioned from the lung allocation score to the composite allocation score (CAS) to optimize organ distribution. Although race is not directly incorporated, the CAS was designed to increase equity. This study evaluates race-related outcomes following implementation of the CAS in lung transplantation.

The United Network for Organ Sharing database was queried for lung transplants between March, 2022 and March, 2024. Patients were classified by transplant date before (lung allocation score) or on/after (CAS) September 3, 2023. Analyses were performed within White, Black, Hispanic, and Asian/other recipient groups. The primary outcome was 90-d survival. Comparative statistics assessed group differences and logistic regression assessed whether the allocation system change was independently associated with 90-d survival.

Waitlist days decreased significantly for Hispanic (28 versus 37, P = 0.001) and Asian/other recipients (21.5 versus 41, P = 0.026), but not for Black or White recipients. Ischemic times and travel distances increased for all races (P < 0.001). In unadjusted survival analysis, 90-d survival did not differ significantly between eras for any group. However, in multivariable models, the CAS era was independently associated with decreased 90-d survival among White recipients (odds ratio: 0.103, 95% confidence interval: 0.082-0.131, P < 0.001).

CAS implementation was associated with shorter waitlist times for Hispanic and Asian/other recipients, suggesting early gains in equity. However, the absence of improvement for Black recipients and decreased adjusted survival for White recipients highlight that allocation reform alone may not fully address disparities in lung transplantation. Future efforts should extend beyond allocation policy to address other potential systemic and institutional barriers.