Effect of broader geographic sharing of donor lungs on lung transplant waitlist outcomes

Abstract

BACKGROUND: The United States lung allocation system prioritizes allocation based on medical urgency and benefit but does not address a federal mandate for broader geographic organ sharing. It is unknown whether broader geographic sharing of donor lungs would improve lung transplant waitlist outcomes. METHODS: A discrete event microsimulation model simulated donor lung allocation according to different geographic lung-sharing policies, including the historic local donor service area (DSA)-based policy and hypothetical policies that prioritize candidates to donors within 500-mile or 1,000-mile geographic radii. Candidate waitlist mortality, number of transplants, and 1-year survival were compared across organ allocation policies. Waitlist mortality rates were further stratified by diagnosis, Lung Allocation Score (LAS) threshold, ABO blood type, and region. RESULTS: Under broader geographic lung sharing, the proportion of chronic obstructive pulmonary disease transplant recipients decreased, whereas the proportion of pulmonary fibrosis recipients increased. Waitlist mortality decreased with broader geographic lung sharing with a 21.3% decrease in waitlist mortality with 500-mile lung sharing and a 31.8% decrease in waitlist mortality with 1,000-mile lung sharing. The decrease in waitlist deaths occured across all U.S. geographic regions and was greatest in candidates with pulmonary fibrosis and/or high medical urgency. CONCLUSIONS: Broader geographic sharing of donor lungs could reduce waitlist mortality, particularly among pulmonary fibrosis and high-medical-urgency candidates.

Impact of the elimination of the donation service area on United States lung transplant practices and outcomes at high and low competition centers

“…There were also no differences in early mortality. This is consistent with studies of broad geographic sharing of lungs under the DSA system, 18,19 and is notable given reports of increased mortality in heart transplant following recent allocation changes. 20 Further study of longterm survival outcomes in the post-DSA era is needed.…”

Perioperative Management of Bleeding and Transfusion for Lung Transplantation

“…There have been numerous diagnostic, surgical, and therapeutic advances since the introduction of lung transplantation that have allowed for the expansion of the donor pool and sustainment of the recipient in anticipation of transplant. [10][11][12][13] Extracorporeal membrane oxygenation (ECMO) is now used extensively throughout the peritransplant period. Preoperatively, ECMO has been described as a bridge-to-lung transplant.…”

Organ Transplantation for Cystic Fibrosis

“…Given recent changes in the lung allocation process resulting in a broader geographic sharing of organs, the median lung allocation score (LAS) of lung transplant recipients has increased, resulting in more patients being transplanted while hospitalized, and on mechanical ventilation and/or extracorporeal membrane oxygenation (ECMO) at the time of transplantation. 66 In fact, the proportion of transplant recipients in the United States who are hospitalized in the ICU before transplant currently is 14.1%. 67 In the past, mechanical ventilation was thought to be a contraindication to transplant given the concern for higher mortality rates.…”

“…100 Moreover, a lawsuit in 2017 led to removal of some geographic constraints to organ allocation and prompted evaluation of geographic sharing that has potential to reduce waitlist mortality. 66,101 Despite these efforts, the LAS remains limited in its ability to identify patients most likely to benefit from transplantation. Waitlist time currently varies from days to 1 to 2 years, with lung candidates with smaller chest cavities, antibodies to human leukocyte antigens (HLAs), and ABO blood group O waiting longer, and those with severe hypoxemia and acute respiratory failure waiting shorter times.…”