Impact of lung allocation policy reforms on center volume redistribution and survival after lung transplantation

Recent policy reforms, including the 2017 implementation of a 250 nautical mile (nm) donor sharing radius and the 2023 introduction of the Composite Allocation Score (CAS), have substantially changed lung allocation in the United States. The effects of these policy reforms on the structural organization of lung transplant programs and associated outcomes remain unclear.

Adult lung transplant recipients in the OPTN/UNOS STAR registry between January 1, 2015 and December 31, 2025 were identified. Transplants performed during the COVID-19 pandemic period (March 2020 to June 2021) were excluded. Allocation eras were defined as lung allocation score-donor service area (LAS-DSA) (January 2015 to November 2017), LAS-250 nm (November 2017 to March 2023), and CAS (March 2023 to December 2025). National concentration of transplant activity across centers was assessed using the Herfindahl-Hirschman Index (HHI) and Gini coefficient. Center volume dynamics were evaluated, and 1-year survival was assessed using Kaplan-Meier and multivariable Cox regression analysis.

Among 25,460 lung transplant recipients, national transplant activity became progressively less concentrated across eras. HHI declined from 0.0273 in the LAS-DSA era to 0.0237 in the CAS era (p<0.001), while the Gini coefficient decreased from 0.436 to 0.384 (p<0.001). Median annualized center transplant volume increased from 23.8/year in the LAS-DSA era to 39.8/year in the CAS era (p=0.051). Unadjusted 1-year survival improved across eras (89.2% LAS-DSA, 89.3% LAS-250 nm, 91.7% CAS; log-rank p<0.001). In adjusted analysis, the CAS era was associated with lower mortality than the LAS-250 nm era (aHR 0.74, 95% CI 0.65-0.83; p<0.001).

Lung allocation reform significantly redistributed transplant activity across U.S. centers while improving survival.