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Effects of the Lung Composite Allocation Score Change on Extracorporeal Membrane Oxygenation (ECMO) Bridge to
Selena S Li1, Adham Makarem1, Antonia Kreso1
1Division of Cardiac Surgery, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts.
Background:
In March 2023, lung allocation changed to the composite allocation score (CAS), aiming to improve access for sicker patients. This study examines CAS effects on patients bridged to transplant (BTT) with extracorporeal membrane oxygenation (ECMO).
Methods:
This United Network for Organ Sharing (UNOS) study included adult lung transplants from January 1, 2022, to June 1, 2024, excluding multiorgan, prior lung transplants, and loss to follow-up. We compared ECMO BTT use and time on ECMO pre-CAS vs post-CAS. Propensity-matched analysis assessed postoperative outcomes in the ECMO BTT subgroup.
Results:
Among 6406 recipients, ECMO BTT rates decreased post-CAS (5.8% vs 7.8%, P = .002), with fewer venoarterial and venovenous cases (P = .011). Fewer ECMO patients were listed post-CAS (8.3% vs 10.3%, P = .005), but transplant rates for listed ECMO patients were similar (59.3% vs 63.3%, P = .242). In the ECMO BTT subgroup, post-CAS recipients were older (median age 55 vs 50 years, P = .001), previous smokers (44.4% vs 30.5%, P = .004), with fewer coronavirus disease diagnoses (3.1% vs 32.6%, P < .001). ECMO type did not differ (P = .635). Time from ECMO to transplant significantly decreased (median 7 vs 19.5 days, P < .001), as did total waiting list time (median 8.5 vs 17.0 days, P < .001). Postoperatively, reintubation was higher for ECMO BTT patients post-CAS (22.3% vs 12.8%, P = .013), which persisted after matching. Other outcomes (ECMO at 72 hours, airway dehiscence, length of stay, and 30-day mortality) were similar.
Conclusions:
Under CAS, ECMO BTT listings and transplants both decreased. However, those who do undergo transplantation receive lungs with shorter waiting list times and time on ECMO. Long-term outcomes remain to be determined.
