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OPTN/UNOS committee proposes liver transplant redistribution
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The Organ Procurement and Transplantation Network and the United Network for Organ Sharing Liver and Intestinal Organ Transplantation committee proposed an eight-district redistribution for liver transplants. The committee members predict their model will cut in half the current variance in median MELD at transplant.
“This proposal seeks to modify these boundaries to better match organ supply with demand, ensuring more equitable access for those in need of liver transplant regardless of their place of residence,” Christine M. Flavin, MPH, in the UNOS policy department, wrote. “This proposal provides the benefit of improved geographic access to transplant but avoids the inefficient and costly transport of livers to candidates of nearly identical allocation priority and medical urgency.”
The United States is currently divided into 11 regions and 58 smaller donation service areas. This design was created decades ago, Flavin wrote, and was created based on the working relationships of that time. As a result, some states require higher MELD scores to receive a transplant. The greatest required-MELD difference is 12 points (35 vs. 23), which is a 60% difference in estimated risk for 3-month mortality without transplant. Further, recent studies estimated a 14-fold difference among donation service areas in waiting list addition rates and a threefold difference in waiting list-eligible deaths.
The Organ Procurement and Transplantation Network and the United Network for Organ Sharing (OPTN/UNOS) proposes a new eight-district model with additional priority of three MELD points for candidates within the district and a 150-mile radius of the donor hospital. Candidates within the 150-mile radius but outside the district will receive an additional three MELD points when sharing nationally. The committee also proposes district-wide sharing for all pediatric candidates as well as sharing of adult deceased donor livers for all candidates with a MELD of at least 29.
The proposed distribution system used the following guidelines:
- Each district must respect existing donation service area boundaries;
- each district must have at least six transplant centers;
- the total number of districts must be between four and eight;
- there must not be a “significant increase” in waiting list death rate;
- the median volume-weighted travel time must be fewer than 3 hours.
OPTN/UNOS performed Liver Simulated Allocation Model analyses based on data of organs donated between 2007 and 2011. In these analyses, the proposed model was projected to cut in half the current variance in median MELD at transplant (2.9 vs. 6.2). The analyses projected the variance in transplant rates to decrease, but did not project transplant deaths to increase. The analyses also predict a decrease in median transport distance (200 miles) and percentage of organs flown (68.3%). Further, the analyses predict about 95% of transplants to occur within the district and 50% within the 150-mile proximity circle. However, the analyses project less than a 2% decrease in the number of transplants per year.
“The goal of this project is to reduce the geographic variance in median MELD at transplant among the estimated 15,000 candidates waiting for a lifesaving liver transplant each day,” Flavin wrote. “This means that many candidates in what are currently regions with lower organ availability will have greater access to lifesaving organs and will likely be transplanted at lower MELD scores.”– by Will Offit
Reference: OPTN/UNOS Liver and Intestinal Organ Transplantation Committee. Redesigning Liver Distribution. Available at: https://optn.transplant.hrsa.gov/governance/public-comment/redesigning-liver-distribution/. Accessed August 17th, 2016.
Disclosure: The researchers report no relevant financial disclosures.
Perspective
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Helen S. Te, MD, FAASLD, FAST, AGAF
The most recent Organ Procurement and Transplantation Network/United Network for Organ Sharing Public Comment Proposal, “Redesigning Liver Distribution”, outlines the most radical changes in the allocation of donor livers since the adoption of the MELD score for organ allocation in February 2002. Redesigning the allocation map to eight districts is aimed to give similar candidates equal access to transplant regardless of where they are listed. The current model has a variance in median allocation MELD/PELD at transplant of 6.2, and this is predicted to decrease to 2.2 in the new model.
This model is one of several that were analyzed for impact on allocation parity, and this had the best prediction of leveling the disparity. It must be pointed out, though, that the LSAM modeling on which this proposal is based used actual patient data prior to the implementation of Share 35. As such, its predictions are not going to be applicable to today’s climate, which has evolved since Share 35.
In this model, there is also a projected less than 2% decrease in transplants. It would be good to even out the MELD at allocation, but to do less transplants in the process is unacceptable, as this translates to depriving some patients of the life-saving procedures and/or discarding usable organs in the process. Sharing organs may promote stronger working relationships between the accepting transplant center and the local procurement teams, but the additional costs of flying organs can be quite limiting for small liver transplant programs, bringing their capacity to thrive and benefit from the new allocation model into question.
While we can applaud the intent to even out allocation disparity, the plan to change the allocation at this time with the implementation of the new eight-district model seems rash and premature. Considering that the financial cost of a wider sharing of organs is going to be substantial, we should be cautious about adopting any new allocation model before it is truly shown to have realistic predicted results.
The proposed model should be restudied using the most current patient data after Share 35, and an attempt to measure the costs to be incurred with the proposed changes should be done to determine if the higher costs are justified by the predicted results.
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