FT. LAUDERDALE, FLA. – More than a decade ago, the Department of Health and Human Services issued the "Final Rule on Organ Procurement and Transplantation Network Amendments," which was intended to ensure that "organs will be [allocated] based on medical criteria, not accidents of geography." Despite the introduction of this final rule, disparities in waiting list outcomes are known to be significantly influenced by where the transplantation candidate lives, and lower priority candidates are receiving organs at the expense of the more severely ill.
Although all candidates are ranked based on an objective priority score known as the Lung Allocation Score (LAS), lung allocation remains a locally based system. Organs are first allocated based on geography regardless of LAS score. Therefore, organs are initially offered only to the subset of matched lung transplant candidates (based on blood group and size) within the donor’s local Donor Service Area (DSA).
As a result, if an available organ is first accepted for a candidate within the local DSA, it is never offered to potentially more-severely ill candidates at the broader regional or national level – even if the regional or national candidate has a much higher priority score. There is evidence that this is a frequent occurrence, according to research presented by Dr. Mark J. Russo at the annual meeting of the Society of Thoracic Surgeons.
Dr. Mark J. Russo
Dr. Russo and his colleagues analyzed data provided by the United Network for Organ Sharing to determine the frequency with which donor lungs were allocated to local candidates when blood group– and size-matched candidates with a higher LAS existed in the same region.
Their study cohort included all locally allocated organs for double lung transplantation in the United States in the year 2009. The researchers then identified all cases in which ABO blood group– and height-matched (within 10 cm) double-lung candidates in the same region had a higher LAS than did the local candidates who actually received the lung. They also calculated the number of these events in which the LAS difference was greater than 10 and greater than 25. The number of these bypassed regional candidates who then died on the waiting list was also determined.
Among the 580 locally allocated double-lung transplants analyzed, there was a mean of 6.0 blood group – and height-matched double-lung events per transplant (3,454 total, impacting 1,193 different candidates) in the same region where candidates had a higher LAS than did the local candidate who received the organ. A total of 24% (828) of the events involved skipping over a regional candidate with an LAS greater than 10 points higher than the local recipient, with 7.2% (250) of events involving a regional candidate with an LAS greater than 25 points higher than the local recipient. Overall, 185 of the bypassed regional candidates died on the waiting list.
Dr. Russo said that although the issue of transportation is important, generally the adverse impact of an additional hour or two of ischemic time due to transportation is not clinically significant, and should not be a major factor in the decision as to local vs. regional candidates. In addition, the regional candidate is often not far from the donor, he added.
"Ideally, a suitable donor organ would be available for every lung transplant candidate who could benefit from transplantation. Unfortunately, there remains a critical scarcity of donor organs available for transplantation. Therefore, efficient allocation of organs is necessary to ensure maximum benefit from the available organs," according to Dr. Russo, a cardiothoracic surgeon at the University of Chicago Medical Center.
"Locally-based allocation results in a high number of events in which a lung is allocated to a lower-priority candidate when an appropriately matched, higher-priority candidate exists in the same region. As a result, low-priority candidates, defined by an LAS less than 50, account for nearly 90% of lung transplant recipients, while candidates with higher LAS scores, defined by an LAS greater than 75, continue to die at extremely high rates while awaiting transplantation," Dr. Russo stated.
Dr. Russo said further that because this study considered only double-lung candidates, did not consider the possibility of national matching, and did not allow for blood groups to be crossed, it likely significantly underestimates the frequency of these events and lives lost.
"These findings suggest that further study of organ sharing over broader geographies should be pursued to determine if it would improve [waiting] list outcomes, including higher rates of organ allocation to higher-priority candidates, improved survival on the waiting list, and greater net benefit from the organs available for transplantation," he concluded.