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

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.

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.

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.

Broader geographic sharing of donor lungs could reduce waitlist mortality, particularly among pulmonary fibrosis and high-medical-urgency candidates.