Lung Transplantation in the Composite Allocation Score Era: Are Older Candidates Disadvantaged?

Abstract

We examined the impact of the Composite Allocation Score (CAS) on lung transplantation vs waitlist death/deterioration by age. We identified lung transplant candidates listed from 2020 to 2024 in the United Network for Organ Sharing database. Candidates were assigned to categories by age at listing (18-59 years, 60-69 years, and ≥70 years). Lung transplantation vs waitlist death/deterioration was compared across age groups before and after CAS implementation. Multivariable competing risk regression including a CAS interaction term evaluated whether CAS modified the association between age and waitlist outcomes. Separate competing risk models assessed whether age disparities exist after CAS implementation. Of 12,082 candidates listed for lung transplant (median age, 62 years; 39.5%, 18-59 years; 47.0%, 60-69 years; 13.5%, ≥70 years), 8475 were listed in the pre-CAS era and 3607 in the post-CAS era. Compared with the pre-CAS era, the proportion of candidates ≥70 years in the post-CAS era increased from 13.3% to 14.0% (P = .04). In the post-CAS era, lung transplantation within 6 months increased for candidates 18 to 59 years (74.3% vs 79.1%; P = .98) and 60 to 69 years (79.6% vs 80.4%; P = .07) but decreased for candidates ≥70 years (84.8% vs 77.9%; P = .57). Waitlist death/deterioration within 6 months decreased for candidates <70 years but not for candidates ≥70 years (5.6% vs 4.2%; P = .24). Competing risk analyses revealed that in the pre-CAS era, older candidates had a higher likelihood of lung transplantation (60-69 years: subdistribution hazard ratio [SHR], 1.09 [95% CI, 1.03-1.16]; ≥70 years: SHR, 1.23 [95% CI, 1.11-1.36]). However, interaction analyses demonstrated less CAS-associated improvement for candidates 60 to 69 years old (SHR, 0.83; 95% CI, 0.74-0.93; P = .002) and ≥70 years (SHR, 0.62; 95% CI, 0.54-0.71; P < .001). In the post-CAS era, candidates ≥70 years old had a reduced likelihood of lung transplant (SHR, 0.78; 95% CI, 0.69-0.90; P < .001) compared with candidates 18 to 59 years old. CAS implementation was associated with decreased lung transplant access for candidates ≥70 years old.