Disease Specific Long-Term Survival of Extended Criteria Donor Lung Transplantation in Adults: A National Cohort Study

S. Mallick¹, S. Sakowitz², J. Hadaya³, S. Bakhtiyar⁴, N. Chervu², N. K.. Le⁵, P. Benharash^6
1UCLA, Los Angeles, California ²UCLA David Geffen School of Medicine, Los Angeles, California ³David Geffen School of Medicine at UCLA, Los Angeles, California ⁴University of California Los Angeles UCLA, Los Angeles, California ⁵David Geffen School of Medicine at UCLA, Tarzana, California ⁶UCLA Division of Cardiac Surgery, Los Angeles, California

Purpose: Extended criteria donor (ECD) organs serve as a valuable strategy to increase the donor pool in lung transplantation.1,2 The impact of ECD on long-term survival stratified by various disease processes remains uncertain.1,2,3,4,5 We thus compared disease-specific survival rates in recipients of ECD allografts in both single and bilateral lung transplants.

Methods: This was a retrospective analysis of all adult lung transplant recipients captured in the 2005-2023 United Network for Organ Sharing database. Patients were stratified based on their diagnosis at the time of listing as: restrictive lung disease, pulmonary vascular disease, cystic fibrosis, and obstructive lung disease. Consistent with prior work, ECD organs were defined as allografts with two or more of the following deviations from standard criteria: donor age ≥55 years, pO2:FiO2 ≤300mmHg, smoking pack years ≥20, purulent bronchoscopic secretions, or abnormal chest radiographs.2,3 All other allografts were classified as standard criteria donor (SCD). The primary outcome was death after transplantation. Unadjusted 10-year survival was assessed using the Kaplan-Meier method for time-to-event analysis. Multivariable Cox regression models were developed to compare adjusted disease-specific survival between recipients of SCD vs ECD allografts. In a subanalysis, we considered survival among single (SOLT) and bilateral (BOLT) orthotopic lung transplant recipients.

Results: Of 34,044 patients undergoing lung transplantation, 7,908 (23.2%) received an ECD organ. From 2005-2023, the proportion of transplanted ECD organs increased from 14.9% in 2005 to 29.4% in 2017, with a subsequent decrease to 25.6% in 2022 (nptrend < 0.001). The cohort undergoing ECD transplantation was older (57.6 ±12.1 vs 56.4 ±12.8 years, p< 0.001), more commonly female (42.2 vs 39.2%, p< 0.001), and more often of poor functional status (40.7 vs 38.8%, p=0.002). Both the SCD and ECD cohorts were equivalent in average lung allocation score at the time of transplant (48 ±17.9 vs 48 ±18.3, p=0.80).
Relative to SCD, the ECD group, as an aggregate, demonstrated lower 10-year survival overall (29.0 vs 32.3%, p< 0.001). This remained true when considering SOLT (17.5 vs 20.8%, p< 0.02) and BOLT (33.4 vs 38.3%, p< 0.001) (Figure 1). Following risk adjustment, ECD patients with restrictive lung disease demonstrated significantly increased hazard of mortality over 10 years, whilst obstructive lung, cystic fibrosis, and pulmonary vascular disease patients demonstrated equivalent survival relative those with the same diagnosis receiving SCD (Table 1). When considering SOLT, equivalent hazards of mortality were seen across all disease groups. Conversely, evaluating BOLT, both pulmonary vascular disease and restrictive lung disease showed significantly increased mortality hazard.

Conclusion: ECD allografts portended worse 10-year survival as compared to SCD. Restrictive lung disease patients had decreased survival after ECD transplants overall and after BOLT. Pulmonary vascular disease patients demonstrated inferior survival after BOLT using ECD allografts. Differential posttransplant mortality by diagnosis suggests further development of lung allocation algorithms is warranted.

Identify the source of the funding for this research project: No funding