A Simple Prioritization Change to Lung Transplant Allocation May Result in Improved Outcomes

Background: The lung allocation score (LAS) significantly improved outcomes and wait list mortality in lung transplantation. However, mortality remains high for the sickest wait list candidates despite additional changes to allocation distance. Regulatory considerations of overhauling the current lung allocation system have met significant resistance, and changes would require years to implement. This study evaluates whether a modest change to the current system by prioritization of only high-LAS lung transplant candidates would result in lowered wait list mortality.

Methods: The Thoracic Simulated Allocation Model was used to evaluate all lung transplant candidates and donor lungs recovered between July 1, 2009 and June 30, 2011. Current lung allocation rules (initial offer within a 250-nautical mile radius for ABO-identical then compatible offers) were run. Allocation was then changed for only patients with an LAS of50 or higher (high-LAS) to be prioritized within a 500-nautical mile radius with no stratification between ABO-identical and compatible offers. Ten iterations of each model were run. Primary end points were wait list mortality and posttransplant 1-year survival.

Results: A total of 6538 wait list candidates and transplant recipients were evaluated per iteration, for a total of 130,760 simulated patients. Compared with current allocation, the adjusted model had a 23.3% decrease in wait list mortality. Posttransplant 1-year survival was minimally affected.

Conclusions: Without overhauling the entire system, simple prioritization changes to the allocation system for high-LAS candidates may lead to decreased wait list mortality and increased organ use. Importantly, these changes do not appear to lead to clinically significant changes in posttransplant 1-year survival.