Abstract Background On March 9th, 2023, the United Network for Organ Sharing (UNOS) replaced the Lung Allocation Score (LAS) with the Continuous Allocation System (CAS), replacing one-year posttransplant survival in LAS with five-year survival prediction in CAS as well as designating points for transplant efficiency and candidate biology and eliminating geographic boundaries. Although overall wait times have decreased under CAS, the effect of this transition on age-related disparities in waitlist duration have yet to be defined. Methods Using the UNOS-STAR file registry, we identified adult primary lung transplant recipients from March 2013 to June 2025, excluding heart-lung and multi-organ transplants. Patients were subdivided into groups by transplant era (LAS: March 2013 to March 2023; CAS: March 2023 to June 2025). The primary outcome was waitlist duration. A mixed-effects linear model with random intercept for transplant center evaluated the independent association of allocation era and age with wait time. Restricted cubic spline modeling examined non-linear effects of age, and Wilcoxon testing compared wait times across age subgroups stratified by an empirically derived spline inflection point. Results The analytic cohort included 31,089 recipients (LAS = 23,253; CAS = 7,439) from 78 centers across 11 UNOS regions. Overall median waitlist time declined from 44 days under LAS to 27 days under CAS (p 0.0001). In the mixed-effects model adjusting for age and center, CAS was associated with 48 ± 3.5 fewer days on the waitlist (p 0.001), and older age predicted shorter wait times (−0.6 days per year, p 0.001). Spline modeling identified a turning point in the relationship between age and waitlist time at 45.5 years in LAS and 52.6 years in CAS. Below these thresholds, younger recipients had modestly longer waits within both eras (LAS p = 0.002; CAS p = 0.02). Among older recipients, predicted wait times decreased consistently from LAS to CAS, with the most pronounced reductions at 60-70 years (−29 to − 62 days, all p 0.001), but minimal change at age 75 (−4 days, p = 0.80). Observed wait times mirrored these findings (Figure 1). An exploratory spline inflection near 72 years marked the plateau where CAS benefit diminished. Conclusions CAS implementation significantly shortened lung transplant waitlist times across all ages. Although younger recipients continued to experience slightly longer waits, the age-dependent disparity flattened under CAS, suggesting the new allocation system achieved a more equitable distribution of organs without disadvantaging older candidates. This abstract is funded by: None
Olson et al. (Fri,) studied this question.