Performance Changes Following the Revision of Organ Allocation System of Lung Transplant: Analysis of Korean Network for Organ Sharing Data

Development of a Machine Learning-Powered Optimized Lung Allocation System for Maximum Benefits in Lung Transplantation: A Korean National Data

BACKGROUND

An ideal lung allocation system should reduce waiting list deaths, improve transplant survival, and ensure equitable organ allocation. This study aimed to develop a novel lung allocation score (LAS) system, the MaxBenefit LAS, to maximize transplant benefits.

METHODS

This study retrospectively analyzed data from the Korean Network for Organ Sharing database, including 1,599 lung transplant candidates between September 2009 and December 2020. We developed the MaxBenefit LAS, combining a waitlist mortality model and a post-transplant survival model using elastic-net Cox regression, was assessed using area under the curve (AUC) values and Uno's C-index. Its performance was compared to the US LAS in an independent cohort.

RESULTS

The waitlist mortality model showed strong predictive performance with AUC values of 0.834 and 0.818 in the training and validation cohorts, respectively. The post-transplant survival model also demonstrated good predictive ability (AUC: 0.708 and 0.685). The MaxBenefit LAS effectively stratified patients by risk, with higher scores correlating with increased waitlist mortality and decreased post-transplant mortality. The MaxBenefit LAS outperformed the conventional LAS in predicting waitlist death and identifying candidates with higher transplant benefits.

CONCLUSION

The MaxBenefit LAS offers a promising approach to optimizing lung allocation by balancing the urgency of candidates with their likelihood of survival post-transplant. This novel system has the potential to improve outcomes for lung transplant recipients and reduce waitlist mortality, providing a more equitable allocation of donor lungs.

Analysis of the waitlist performance and post-transplant outcomes of lung transplant in elderly recipients in Korea: A nationwide cohort study

BACKGROUND

There is a lack of information on the waitlist performance and post-transplant outcomes of lung transplants in elderly recipients in Korea.

METHODS

We retrospectively reviewed and analyzed data from the Korean Network for Organ Sharing database between March 2010 and August 2023.

RESULTS

In total, 2574 patients were listed for lung transplantation during the study period, with 511 (19.9%) of them being over 65 years of age. Among these, 188 patients (36.8%) underwent transplantation, while 184 patients (36%) passed away without undergoing transplantation at the time of data extraction. The most prevalent underlying disease on the waitlist was idiopathic pulmonary fibrosis, accounting for 68.1%. The 1-year survival rate was significantly lower in the elderly compared to that in the nonelderly (65.4 vs. 75.4%; p = .004). In the multivariate Cox analysis, elderly (hazard ratio [HR], 1.49; 95% CI, 1.14-1.97; p = .004) and a high urgent status at registration (HR, 1.83; 95% CI, 1.40-2.40; p < .001) were significantly associated with post-transplant 1-year mortality. Kaplan-Meier curves demonstrated a significant difference in post-transplant mortality based on the urgency status at enrollment (χ2 = 8.302, p = .016). Even with the same highly urgent condition at the time of transplantation, different prognoses were observed depending on the condition at listing (χ2 = 9.056, p = .029).

CONCLUSION

The elderly exhibited worse transplant outcomes than nonelderly adults, with a highly urgent status at registration identified as a significant risk factor. Unprepared, highly urgent transplantation was associated with poor outcomes.

Patient management for thoracic organ donor candidates: the lung transplantation team's view

Despite the increasing demand for lung transplants, donor lungs remain in short supply. Although organ donations have been steadily increasing in Korea, with the utilization rate for donor lungs increasing to 40% in recent years, many potential donor organs remain unused. To match the increasing number of patients on the lung transplant waitlist, it is essential to increase the donor procurement rate through optimal management. Improvements in donor lung management programs can lead to expansion of the donor pool and optimal posttransplant outcomes. This review focuses on basic protocols for the optimal management of donor lungs and summarizes coronavirus disease 2019-related considerations for donor lung evaluation.

Outcomes of Patients on the Lung Transplantation Waitlist in Korea: A Korean Network for Organ Sharing Data Analysis

BACKGROUND

The demand for lung transplants continues to increase in Korea, and donor shortages and waitlist mortality are critical issues. This study aimed to evaluate the factors that affect waitlist outcomes from the time of registration for lung transplantation in Korea.

METHODS

Data were obtained from the Korean Network for Organ Sharing for lung-only registrations between September 7, 2009, and December 31, 2020. Post-registration outcomes were evaluated according to the lung disease category, blood group, and age.

RESULTS

Among the 1,671 registered patients, 49.1% had idiopathic pulmonary fibrosis (group C), 37.0% had acute respiratory distress syndrome and other interstitial lung diseases (group D), 7.2% had chronic obstructive pulmonary disease (group A), and 6.6% had primary pulmonary hypertension (group B). Approximately half of the patients (46.1%) were transplanted within 1 year of registration, while 31.8% died without receiving a lung transplant within 1 year of registration. Data from 1,611 patients were used to analyze 1-year post-registration outcomes, which were classified as transplanted (46.1%, n = 743), still awaiting (21.1%, n = 340), removed (0.9%, n = 15), and death on waitlist (31.8%, n = 513). No significant difference was found in the transplantation rate according to the year of registration. However, significant differences occurred between the waitlist mortality rates (P = 0.008) and the still awaiting rates (P = 0.009). The chance of transplantation after listing varies depending on the disease category, blood type, age, and urgency status. Waitlist mortality within 1 year was significantly associated with non-group A disease (hazard ratio [HR], 2.76, P < 0.001), age ≥ 65 years (HR, 1.48, P < 0.001), and status 0 at registration (HR, 2.10, P < 0.001).

CONCLUSION

Waitlist mortality is still higher in Korea than in other countries. Future revisions to the lung allocation system should take into consideration the high waitlist mortality and donor shortages.

Allocation of Donor Lungs in Korea

The expansion of indications for lung transplantation, the growth of the waiting list, and donor shortages are increasing the waiting list mortality rate in Korea. The current lung allocation system in Korea is based mainly on urgency, but outcomes should also be considered to avoid futile transplantation. This review describes the current status of, and issues with, the lung allocation system in Korea including donors, the waiting list, and transplant outcomes in the context of an aging society, in which the frequency of end-stage pulmonary disease is increasing.

Lung Transplantation for Patients with COVID-19 Acute Respiratory Distress Syndrome

Patients with severe coronavirus disease 2019 (COVID-19) acute respiratory distress syndrome (ARDS) may exhibit pulmonary fibrosis after the viral illness resolves. Some of these patients may experience severe functional lung impairment, and thus require transplants to prevent death or maintain a tolerable quality of life. Considering the reversibility of COVID-19 ARDS, lung transplant candidates are observed for 1–2 months and must be selected very carefully before transplantation. As the short-term outcomes of such patients are comparable to those of patients with other indications for transplantation, lung transplantation should be actively considered.

Successful lung transplantation after prone positioning in an ineligible donor: a case report

Atelectasis is a reversible factor in hypoxemia among brain-dead donors. In ineligible donors, prone positioning reverses atelectasis and improves oxygenation. We present a successful lung transplantation after salvaging a previously unviable lung. A 37-year-old woman presented with acute pontine hemorrhage that progressed to brain death. The initial partial pressure of oxygen (PaO₂)/fraction of inspired oxygen (FiO₂) ratio of the donor’s lung was 342 mmHg. The PaO₂/FiO₂ ratio dropped to 49 mmHg due to atelectasis. There was no improvement despite recruitment maneuvers, bronchoscopy, and chest percussion. After placing the donor in the prone position for four hours, electrical impedance tomography showed improved atelectasis. The donor did not experience hemodynamic instability. The lung was transplanted into a patient with Kartagener’s syndrome with situs inversus. The surgical procedure was uneventful. He was successfully weaned from the mechanical ventilator on the second-day post-transplantation and was discharged from the hospital after 4 weeks.