Early outcomes of lung transplantation under the composite allocation score system

The Composite Allocation Score was introduced in March 2023 with the goal of improving organ allocation for potential lung transplant recipients. The purpose of this study is to characterize waitlist and post-transplant outcomes for adult lung transplant recipients under the Composite Allocation Score policy.

We included all adult candidates listed for isolated lung transplantation in the United States from May 2022 to December 2023. Candidates were categorized into 2 eras: Era 1 (pre-Composite Allocation Score, May 15, 2022 to March 8, 2023) and Era 2 (post--Composite Allocation Score, March 9, 2023 to December 31, 2023). Waitlist mortality and transplant rates within 9 months of listing were compared using competing risk regression. Post-transplant outcomes of the 2 groups were also compared. Kaplan-Meier was used to evaluate 9-month survival post-transplant.

A total of 5293 candidates were listed, with 2744 (51.8%) during Era 2. Lung transplant candidates in Era 2 experienced lower waitlist mortality (sub-hazard ratio, 0.79; 95% CI, 0.69-0.92, P = .002) and higher transplant rates (sub-hazard ratio, 1.22; 95% CI, 1.15-1.28, P < .001) compared with those in Era 1. Post-transplant extracorporeal membrane oxygenation rates at 72 hours (11.1% vs 9.9%, P = .25) and 30-day mortality (2.3% vs 2.4%, P = .96) were similar between Era 2 and Era 1. Nine-month survival after transplantation was not significantly different between Era 2 and Era 1 recipients (91.7% vs 90.9%, P = .47).

Lung transplant candidates in Era 2 had lower waitlist mortality and higher transplant rates compared with Era 1, with similar 9-month post-transplant survival. These findings suggest that the Composite Allocation Score policy has contributed to allocation improvement without compromising early post-transplant outcomes.