Trends in marginal lung allograft survival: Advanced-age donors improve.

INTRODUCTION: Although lung demand continues to outpace supply, 75% of potential donor lungs are discarded without being transplanted in the United States. To identify the discarded cohorts best suited to alleviate the lung shortage and reduce waitlist mortality, we explored changes in survival over time for five marginal donor definitions: age >60 years, smoking history >20 pack-years, PaO2 /FiO2  < 300 mmHg, purulent bronchoscopic secretions, and chest radiograph infiltrates. METHODS: Our retrospective cohort study separated 27 803 lung recipients in the UNOS Database into three 5-year eras by transplant date: 2005-2009, 2010-2014, and 2015-2019. Multivariable Cox proportional hazards regression and Kaplan-Meier analysis with log-rank test were used to compare survival across the eras. RESULTS: Three definitions-low PaO2 /FiO2 , purulent bronchoscopic secretions, and abnormal chest radiographs-did not bear out as truly marginal, demonstrating lack of significantly elevated risk. Advanced donor age demonstrated considerable survival improvement (HR (95% CI): 1.47 (1.26-1.72) in 2005-2009 down to 1.14 (.97-1.35) for 2015-2019), with protective factors being recipients <60 years, moderate recipient BMI, and low Lung Allocation Score (LAS). Donors with smoking history failed to demonstrate any significant improvement (HR (95% CI): 1.09 (1.01-1.17) in 2005-2009 increasing to 1.22 (1.08-1.38) in 2015-2019). CONCLUSIONS: Advanced donor age, previously the most significant risk factor, has improved to near-benchmark levels, demonstrating the possibility for matching older donors to healthier non-elderly recipients in selected circumstances. Low PaO2 /FiO2 , bronchoscopic secretions, and abnormal radiographs demonstrated survival on par with standard donors. Significant donor smoking history, a moderate risk factor, has failed to improve.

Allograft discard risk index for lung transplantation.

BACKGROUND: The demand for donor lungs continues to outpace the supply, yet nearly 75% of donor lungs intended for lung transplantation are discarded. METHODS: We reviewed all donation after brain death organ donors listed within the UNOS Deceased Donor Database between 2005 and 2020. Univariable and multivariable analyses were run on the training set (n = 69,355) with the primary outcome defined as lung discard, and the results were used to create a discard risk index (DSRI). Discard data were assessed at DSRI value deciles using the validation set (n = 34,670), and differences in 1-year mortality were assessed using stratum-specific likelihood ratio (SSLR) analysis. RESULTS: Donor factors most associated with higher DSRI values included age > 65, PaO2 < 300, hepatitis C virus, and cigarette use. Factors associated with lower DSRI values included donor age < 40 and PaO2 > 400. The DSRI was a reliable predictor of donor discard, with a C-statistic of 0.867 in the training set and 0.871 in the validation set. The DSRI was not a reliable predictor of 30-day, 1-year, 3-year, and 5-year survival following transplantation (C-statistic 0.519-0.530). SSLR analysis resulted in three 1-year mortality strata (SSLR 0.88 in the 1st DSRI value decile, 1.03 in the 2nd-5th, & 1.19 in the 6th-10th). CONCLUSIONS: The factors leading to lung allograft discard are not the same as those leading to worse recipient outcomes. This suggests that with proper allocation, many of the grafts that are now commonly discarded could be used in the future donor pool with limited impact on mortality.