Lung transplantation disparities based on diagnosis for patients bridging to transplant on extracorporeal membrane oxygenation

Background: Extracorporeal membrane oxygenation (ECMO) is increasingly utilized as a bridge to lung transplantation, but ECMO status is not explicitly accounted for in the Lung Allocation Score (LAS). We hypothesized that among waitlist patients on ECMO, patients with pulmonary arterial hypertension (PAH) would have lower transplantation rates.

Methods: Using United Network for Organ Sharing data, we conducted a retrospective cohort study of patients who were ≥12 years old, active on the lung transplant waitlist, and required ECMO support from June 1, 2015 through June 12, 2020. Multivariable competing risk analysis was used to examine waitlist outcomes.

Results: 1064 waitlist subjects required ECMO support; 40 (3.8%) had obstructive lung disease (OLD), 97 (9.1%) had PAH,138 (13.0%) had cystic fibrosis (CF), and 789 (74.1%) had interstitial lung disease (ILD). Ultimately, 671 (63.1%) underwent transplant, while 334 (31.4%) died or were delisted. The transplant rate per person-years on the waitlist on ECMO was 15.41 for OLD, 6.05 for PAH, 15.66 for CF, and 15.62 for ILD. Compared to PAH patients, OLD, CF, and ILD patients were 78%, 69%, and 62% more likely to undergo transplant throughout the study period, respectively (adjusted SHRs 1.78 p = 0.007, 1.69 p = 0.002, and 1.62 p = 0.001). The median LAS at waitlist removal for transplantation, death, or delisting were 75.1 for OLD, 79.6 for PAH, 91.0 for CF, and 88.3 for ILD (p < 0.001).

Conclusions: Among patients bridging to transplant on ECMO, patients with PAH had a lower transplantation rate than patients with OLD, CF, and ILD.