Candidate place-based factors before and after composite allocation score implementation in lung transplantation in the United States.

BACKGROUND

In March 2023, the Composite Allocation Score (CAS) and continuous distribution replaced the Lung Allocation Score (LAS) for lung transplantation in the United States in part to reduce the role of geography. We examined whether ZIP-code-level socioeconomic drivers of waitlisted patients were associated with time to transplant or waitlist attrition, defined as death or removal due to being too sick.

METHODS

Candidates waitlisted between January 1, 2021, and November 29, 2025 in the Scientific Registry of Transplant Recipients were included. Place-based measures were the Social Deprivation Index (SDI) and Local Internet Availability (LIA). Fine-Gray competing risks regression models were used. The primary outcome was time from listing to transplant or waitlist attrition.

RESULTS

Among 15,178 patients, 6178 were from the LAS era and 9000 during CAS. The SDI did not differ between eras (43.0 during LAS and 45.0 during CAS (p =0.18)), and LIA modestly decreased (8.4% during LAS and 6.3% during CAS (p <0.001)). In the CAS era, candidates from low LIA areas, when compared to moderate/high LIA areas, were more likely to have obstructive lung disease, reside outside major metropolitan counties, and travel farther to their listing center. After multivariate modeling, there was no association between SDI or LIA and time from listing to transplant or waitlist attrition.

DISCUSSION: In this early evaluation of CAS, place-driven factors at the zip-code-level were not associated with lung transplant waitlist outcomes after CAS implementation. However, descriptive differences by candidate LIA areas warrant continued monitoring and longer-term follow-up.