Update on Continuous Distribution of Livers and Intestines
At a glance
In December 2018, the OPTN Board of Directors approved the continuous distribution framework for allocation of all organs. Continuous distribution will rank waiting list candidates based on points for various factors, such as medical urgency, candidate biology, patient access, and placement efficiency. Continuous distribution will remove the hard boundaries built into the current framework to increase equity for patients and transparency in the system.
This request for feedback builds upon the 2022 concept paper, provides an overview of the project’s development process and progress, and offers next steps for continuous distribution of livers and intestines. The paper also requests community feedback that will assist the Liver and Intestinal Organ Transplantation Committees’ work.
Requested feedback — Liver Values prioritization exercise
- The community is asked to participate in a liver values prioritization exercise. The liver values prioritization exercise, which uses an Analytical Hierarchy Process (AHP) methodology, will help the committee determine how to rank the various attributes used to develop a composite allocation score.
Watch Colleen Reed, PhD, MSW, a liver transplant recipient who serves on the OPTN Liver and Intestinal Organ Transplantation Committee, explain the continuous distribution framework and how patients, donors, and their families can provide feedback on the project.
Watch James Pomposelli, MD, PhD, chair of the OPTN Liver and Intestinal Organ Transplantation Committee provide an overview of the request for feedback on continuous distribution of livers and intestines and how to participate in the values prioritization exercise.
Additional feedback requested
- The community is asked to provide feedback on the committee’s progress to date and the plan for moving the project forward
- The committee is seeking feedback on the proposed list of attributes to be included in the first iteration of continuous distribution
- What it's expected to do
- Provide a more equitable approach to matching candidates and donors
- Remove hard boundaries that prevent candidates from being prioritized higher on the match run
- Establish a system that is flexible enough to work for each organ type
- What it won't do
- This request for feedback is not a proposed policy change, but will help the Liver and Intestinal Organ Transplantation Committees develop a future policy proposal
Terms to know
- Attribute: Criteria used to classify then sort and prioritize candidates. For example, in liver allocation, criteria include medical urgency, post-transplant survival, candidate biology, patient access, and placement efficiency.
- Analytical Hierarchy Process (AHP): An exercise that asks participants to rate the importance of an attribute when it is compared to another attribute.
- Composite Allocation Score: Combines points from multiple attributes together. This request for feedback proposes the use of composite allocation scores in a points-based framework.
- Rating Scale: Describes how much preference is given to candidates within each attribute.
- Weights: Reflect the relative importance or priority of each attribute toward the overall goal of organ allocation. Combined with the ratings scale and each candidate’s information, this results in an overall composite score for prioritizing candidates.
Hume-Lee Transplant Center | 03/18/2023
This is a burdensome and complicated process. It further complicates allocation. It is essentially handing a handful of people the ability to twist dials and reallocate organs from patient to patient. It is also frankly unexplainable to the patients themselves.
Society for Pediatric Liver Transplantation | 03/15/2023
The Society of Pediatric Liver Transplantation (SPLIT) appreciates the work on continuous distribution by the OPTN Liver and Intestine Committee. We want to ensure that as we move forward, we protect the work that has been done in adjusting pediatric priority in the last 2 years – particularly in updating the PELD score based on newer data, using continuous instead of categorical variables, and using age-adjusted mortality to calibrate pediatric to adult medical urgency scores. We encourage continued collaboration and integration of feedback from the Pediatric Committee as well as patient advocacy groups who work with children to ensure pediatric patients are considered in each weighted category.
We strongly support the Committee’s additional efforts to provide additional priority to candidate-donor matches that will be split liver transplants (creating 2 transplants from 1 organ). We agree with priority for candidates that are initiating split liver transplants, overall increasing the number of liver transplants. In addition, it is important that the metric is accurate in prediction of initiation, and does not just reflect that "willingness to accept a split transplant.”
If the Liver Committee intends to replace PELD/MELD with a new medical urgency score (OPOM), it is critical that the score that will be applied to children and adolescents be derived from pediatric/adolescent specific data in collaboration with the pediatric liver transplant community. It will be important to evaluate the new score against PELD in simulations, and that it maintains recent improvements in PELD including calibration of pediatric to adult scores based on age-adjusted mortality predictions, not overall mortality predictions.
Piedmont Atlanta Hospital | 03/15/2023
Piedmont Hospital thanks the Liver and Intestinal Transplant Committee for the opportunity to provide feedback, and offers the following comments for consideration:
Piedmont Hospital supports the optimization of the MELD score to capture medical urgency. OPOM must be validated prior to any implementation, utilizing additional entities to evaluate both retrospective and prospective data. Moving to OPOM without validation is a safety concern for our population, as well as a waste of valuable resources. Furthermore, the improvement of standardized exception scoring has been extremely beneficial to our patient population, and this proposal does not clearly account for those recipient subsets. Living donors should be considered a priority and have a standardized exception.
Post-Transplant mortality metrics should be defined and included. We applaud the committee's work to implement this measure, and it would be remiss to not include this at implementation. Race, socioeconomic status and geography do affect access to care and post-transplant survival. Previously defined disparities are available in multiple reporting structures and highlight disparities, including race and geographic location.
Rational, safe and resource-aware transportation practices absolutely need to be considered. However, this cannot be at the expense of patient safety. Further analysis of the allocation changes that were already implemented are needed. We have yet to see validated data to understand the impact and burden of these changes. Failure to compile, review and understand this data will lead to continued waste of valuable resources.
Center and OPO utility of DCD organs and the impact of normothermic perfusion and advancement of clinical practice should also be considered and are not incorporated in this proposal.
Region 6 | 03/15/2023
Members in the region offered several suggestions for the committee to consider as they continue towards Continuous Distribution. One attendee commented that the distribution of livers should be data-driven to maximize life-years of the graft. Two attendees commented that models should include attributes such as DCD recipient and especially post-transplant survival. Several attendees commented that post-transplant survival should be considered in the liver CAS. One added that adding post-transplant survival is imperative to avoid futile transplants. One attendee commented that distance needs to be prioritized so we are not promoting inequities for centers who don’t have the technology available to accept organs from long distances. One attendee commented that this would be a good time to replace MELD with OPOM for medical urgency scores. One attendee wanted more information about how donor attributes would be considered in the new system.
Region 11 | 03/15/2023
A member commented that improvements in infrastructure is needed to achieve the intent of continuous distribution as there have been increased expenses and logistical complications with new allocation policies. They also commented that the variability across OPOs impacts transplant and some regions will experience a decrease in transplants and there is potential for increased non-utilization.
OPTN Living Donor Committee | 03/15/2023
The OPTN Living Donor Committee thanks the OPTN Liver and Intestinal Organ Transplantation Committee for their work on continuous distribution. The Committee strongly supports that prior living donors receive prioritization in this new allocation system, for though the reality of a living donor needing a future transplant is not frequent, the Committee deems it important from both an ethical and clinical perspective. Ensuring prioritization for prior living donors also maintains confidence in the organ donation and transplantation system, and this is a factor not to be undermined while developing continuous distribution.
OPTN Minority Affairs Committee | 03/15/2023
The Minority Affairs Committee thanks the Liver and Intestinal Organ Transplantation Committee for the opportunity to provide feedback on the concept paper, Update on Continuous Distribution of Livers and Intestines.
The MAC discussed the importance of the patient access goal and agrees that the prior living donor attribute should be incorporated in the liver continuous distribution framework. The members of MAC inquired if the points value will differ among different living organ donors or if all organ types will have the same point value. While this topic is still an ongoing discussion among the Liver Committee, the MAC encourages the Liver Committee to give additional consideration to the points value that will be assigned to this attribute.
Lance Stein | 03/15/2023
Providing sequential improvements to donor allocation and recipient matching is a complicated task. I applaud the effort to improve the allocation systems. My general conclusion is that this process needs to move slower than currently planned as any unforced errors will cost lives and waste taxpayer money. There are many positives the current proposed continuous distribution of liver and intestines. However, there also exist significant challenges/concerns listed here in no order:
1. MELD 3.0 and the current mile radius structures should be given a chance to be better understood prior to consideration of OPOM. OPOM needs to have validated retrospective and prospective data and shared with the stakeholders prior to implementation given the opacity of the current OPOM metrics.
2. Need to incorporate local center utility of DCD organs and the impact of NPM (pumping) which is excluded here.
3. Post transplant mortality does exist in many forms. These rules should not be approved without including post transplant mortality metrics in some form. In fact, all centers are "judged" on outcomes accumulated and reported by the SRTR and shared via open access format. If SRTR is able to understand risks and hazard ratios for post transplant survival, why cannot this be incorporated "despite limited good quality data sets". Post transplant mortality is understood in retranspant, ACLF grading, ALF, frailty, low BMI, and other medical co-morbidities, distance from transplant center, socioeconomic status etc.
4. Weight and impacts of the various factors are important and cannot just be given and reassessed in real time or accounted for by an exercise judging 10 year wait time versus a child.
5. Currently identified attributes other than MELD cannot be weighted in any way near MELD. ie. MELD is the most important factor and should be weighted as such
6. HCC and other appropriate MELD exceptions (ie. PCLKD, CCA) aren't clearly accounted for.
7. This model needs to include the local impact of residing in/near poorly performing OPOs. OPO standards need to be set and adhered to.
8. Population density models cannot be rolled out without validated data. Data show that rural and far from transplant center communities are impacted negatively. We cannot draft models that widen this gap. Also population centers often have a glut of transplant centers without any improvement to the local communities in terms of transplant rates, organ utility, survival, or lowering costs.
9. Concerns regard height/BSA which can be "gamed" with volume status.
10. Points should be given to ground transportation > flying
11. a system of organ swapping or flexibility based on new offers and distance from centers needs to be created/established.
In short, the planned transition to continuous allocation is necessary. However the execution needs to be as comprehensive as possible, based on validated data, include behaviors of local centers/OPOs, make transplant more accessible and be better stewards of health dollars by trying to reduce transportation.
Jon Hundley | 03/15/2023
1. The MELD score has hundreds of studies that have validated it’s accuracy as a predictor of patient mortality on the waitlist. OPOM has been validated by only one research group which includes members who have previously shown an extreme lack of objectivity when it comes to liver allocation discussions and therefore needs further validation before implementation. OPOM’s data cohort was from 2002-2016 which might have well been a century ago considering the number of allocation changes that we have suffered through the last twenty years. It would be reckless to switch from MELD to OPOM without further validation by other groups and using a more recent cohort of patients.
2. I agree with the committee’s desire to implement a measure of patient survival like kidney’s EPTS score. I disagree with the conclusion, however, that due to lack of data we should proceed with continuous distribution without including this important component.
3. Giving priority in advance to “splittable” livers when so many liver segments are discarded in the attempt to split the allograft should not occur.
4. Choosing not to include the candidates’ social determinants of mortality is lazy and unforgiveable. There is clear data that shows that socioeconomic status, race, and geography all impact waitlist mortality. These factors particularly affect candidates living in poor and rural areas. We have fought this fight for years, but it has been ignored by the leaders of the OPTN who largely represent centers filled with candidates of privilege. I’m not surprised that you are choosing to ignore these patients again.
Association of Organ Procurement Organizations | 03/14/2023
Thank you for the opportunity to submit comments on the Organ Procurement and Transportation Network’s (OPTN’s) policy development process on behalf of the Association of Organ Procurement Organizations (AOPO). AOPO collectively represents 48 federally designated, non-profit Organ Procurement Organizations (OPOs) in the United States, which together serve millions of Americans. As an organization, AOPO is dedicated to providing education, information sharing, research, technical assistance, and collaboration with OPOs, other stakeholders, and federal agencies to continue this nation’s world-leading transplantation rates while consistently improving towards the singular goal of saving as many lives as possible. We offer the following comments for your consideration:
As stated in our previous comment for liver, lungs, and kidneys, AOPO views the continuous distribution framework as an effective way to balance multiple medical and efficiency-based factors in a patient-focused manner. Continuous distribution will also provide future flexibility by allowing the OPTN to be more nimble in its ability to adjust and change the relative weighting of attributes as conditions for organ distribution evolve over time.
AOPO recognizes that continuous distribution was specifically endorsed by the National Academy of Science, Engineering and Medicine in its recent study, “Realizing the Promise of Equity in Organ Transplantation”, as one of the strategies to ensure a more equitable system of transplantation (see Recommendation 4). AOPO agrees with the Liver Committee’s work to balance consideration of waitlist mortality with maximizing post-transplant outcomes and to consider placement logistics and efficiency to ensure the risk of discard is minimized.
AOPO supports the rationale for exploring the continuous distribution of livers and intestine as stated in the proposal:
• Provide a more equitable approach to matching liver and intestine candidates and donors. • Remove hard boundaries that prevent liver and intestine candidates from being prioritized further on the match run.
• Consider multiple candidate attributes all at once through a composite allocation score, instead of within categories by sequence.
• Establish a system that is flexible enough to work for each organ type.
AOPO will focus its response on the following questions posed by the Committee.
Attributes for livers and intestines: AOPO supports the five categories selected for evaluating liver allocation: Medical Urgency, Post-Transplant Survival, Candidate Biology, Patient Access, and Placement Efficiency. Assignment of weights to each category should be informed by the goals of maximizing the gift to benefit patients and donor families, transplanting the sickest patients, creating allocation efficiencies, and reducing discards.
How to incorporate the attributes: The allocation system should be designed, and factors weighted in a manner which clearly reflects good stewardship and maximizes the opportunity for transplant to honor the donor and the donor family decision to donate. Predictively accurate modeling is critical to achieving the balance between equity and efficiency factors and maximizing transplants of livers and intestines. AOPO agrees with the proposal’s incorporation of efficiency attributes to ensure “smarter” distribution by distributing organs over further distances with increased costs and lower efficiencies only for significant clinical differences. Transportation challenges compound when sending organs longer distances and should be considered to balance equity and minimizing discards. AOPO also recommends the Committee consider how donor factors impact the efficiency calculation. Longer travel times combined with clinically complex donor organs will create different behaviors (turndowns) as compared to longer travel times with less complex donor organs. To that end, we urge the Committee to consider incorporation of attributes related to ex vivo devices which are rapidly improving the ability to utilize previously non-transplantable livers and facilitate transportation of livers over longer distances without impacting transplantability.
AOPO supports a system that provides priority points to prior living donors, pediatric recipients, and candidates with biological challenges, such as height. However, these attributes must be balanced with travel efficiency and proximity to ensure maximum usage of donated organs.
In addition, AOPO supports language providing OPOs with more discretion in allocation in general and particularly in the early implementation of continuous distribution. Providing OPOs discretion to allocate from the liver list before allocating from the intestine list for patients with higher composite allocation scores will allow OPOs to address circumstances unique to donor situations that may arise. This flexibility will be essential to maximize the benefit of donated organs. AOPO supports the growing practice of utilizing local recovery surgeons that allow OPOs to focus on getting the organ transported, as opposed to also having to find a team to do the recovery as well. This maximizes efficiency and cost and allows greater flexibility with scheduling OR time.
Finally, AOPO recommends UNOS review policies and practices which allow transplant programs to accept more than one liver at a time for the same recipient. Experience demonstrates that this practice results in late turndowns and the need for emergent reallocation intra-operatively or post recovery which dramatically increases the likelihood an organ will go unused, and a life-saving gift wasted.
Whether the medical urgency score in liver allocation should switch from MELD and PELD to OPOM: AOPO supports the advancement of an allocation system which ensures equitable access for all waitlisted candidates, reduces waitlist and immediate post recovery mortality, and is data-driven to encourage the use of more complex organs for the right recipient. Optimized prediction of mortality (OPOM) has been suggested as a more advanced machine learning tool which predicts a candidate’s waitlist mortality more successfully than MELD/PELD. The modeling of OPOM also more accurately and objectively prioritized candidates for liver transplant resulting in a significant number of additional lives saved each year. We would encourage further testing of the OPOM to ensure it meets all the criteria AOPO supports and leads to more patients being transplanted.
Donor Network of Arizona | 03/14/2023
Donor Network of Arizona is pleased to see the progress that continues to be made with continuous distribution. Any allocation system must balance patient needs with system efficiency, and DNA encourages the committee to continue exploring how best to balance the stated goal of getting organs to the sickest patients quickly without making the system inefficient by requiring multiple offers be made before a recipient is found. We note that the recent implementation of continuous distribution for lungs has resulted in east coast center candidates at the top of west coast lung matches, even though the east coast centers in question have no intention of traveling that far for those organs. The new policy should require that centers use appropriate filters (size, distance, etc.) to reduce the number of unacceptable offers transmitted.
Region 7 | 03/14/2023
Several members commented that more information was needed for the split liver attribute including how center practices affect allocation. Several members stated that post-transplant outcomes should be included in the attributes. A member commented that points for women, size, and race should be included. A member asked that priority be given to important attributes and commented that waiting time is not the best way to allocate livers as patients can be listed without a need for transplant just to start gaining time.
Region 1 | 03/14/2023
An attendee commented that this is an important step forward in improving liver allocation in a patient-centered methodology, and we will need to remain open and flexible as we adjust components and their values going forward. A member remarked that while the idea is great, the key is to how weights are assigned to each factor and that it should be data driven and not based on community sentiment. Another member stated that they believe the cost and complexity of broader distribution rises much more quickly than any survival benefit of broader sharing. An attendee complimented on the committees moving this project forward and asked that they ensure efficiency factors are supported with clearly articulated rationale and do not result in inequitable outcomes.
Gift of Life Michigan | 03/14/2023
Gift of Life Michigan views the continuous distribution framework as an effective way to balance multiple medical and efficiency-based factors in a patient-focused manner. Continuous distribution will also provide future flexibility by allowing the OPTN to be more nimble in its ability to adjust and change the relative weighting of attributes as conditions for organ distribution evolve over time. Gift of Life Michigan recognizes that continuous distribution was specifically endorsed by the National Academy of Science, Engineering and Medicine in its recent study, “Realizing the Promise of Equity in Organ Transplantation”, as one of the strategies to ensure a more equitable system of transplantation (see Recommendation 4). This policy also aligns with the HRSA requirement of removing geographic barriers as an allocation method. We support the balance consideration of waitlist mortality with maximizing post-transplant outcomes. We believe heavy consideration should be made to consider placement logistics and efficiency to ensure the risk of organ non-utilization is minimized.
Attributes for livers and intestines: We support the five categories selected for evaluating liver allocation: Medical Urgency, Post-Transplant Survival, Candidate Biology, Patient Access, and Placement Efficiency. Assigning appropriate weights to each category must guarantee organ allocation is improved and livers do not go unused. The allocation system should be designed in a manner that clearly reflects good stewardship. From the OPOs perspective, one of the most important outcomes for donor families is for gifted organs to save lives. Travel efficiency is of particular interest to us and must be considered. Ensuring we can secure adequate transportation in a timely manner that is as efficient and cost-effective as possible is critical. Another area of great concern for us is ensuring organs that suddenly become unplaced in the operating room, or in the immediate hours leading up to the operating room, have the opportunity to be placed using a more efficient allocation process that maximizes utilization.
How to incorporate the attributes: The allocation system should be designed in a manner that clearly reflects good stewardship. One of the most important outcomes for donor families is for gifted organs to save lives. The weighting must prioritize this outcome – lives saved – to the extent data modeling must be predictively accurate. This is an analysis that should be reviewed critically post-implementation and adjusted if needed. Equity and efficiency factors must be balanced to ensure the maximum use of donated livers and intestines. We agree with the proposal’s incorporation of efficiency attributes to ensure “smarter” distribution by distributing organs over further distances with increased costs and lower efficiencies only for significant clinical differences. Transportation challenges are not small when sending organs longer distances and must be considered. The risk of losing an organ all together is increased when travel by plane becomes a factor.
We also recommend the Committee considers how donor factors impact the efficiency calculation. Longer travel times combined with clinically complex donor organs will create different behaviors (turndowns) as compared to longer travel times with less complex donor organs. To that end, we urge the Committee to consider the future incorporation of attributes related to ex vivo devices that are rapidly improving the ability to utilize previously non-transplantable livers and are changing the ability for livers to travel longer distances.
Gift of Life Michigan supports a system that provides priority points to prior living donors, pediatric recipients, and candidates with biological challenges, such as height. However, these attributes must be balanced with travel efficiency and proximity to ensure maximum usage of donated organs.
OPOs should have more discretion in allocation in general and particularly in the early implementation of continuous distribution. Providing OPOs discretion to allocate from the liver list before allocating from the intestine list for patients with higher composite allocation scores will allow us to address circumstances unique to donor situations that may arise. Logistics or unique circumstances will occur in which OPO discretion will be essential to maximize the benefit of donated organs. For example, OPOs may be faced with a deadline for recovery while simultaneously facing clinical circumstances in donor management that may jeopardize the donation overall. We also support utilizing local recovery surgeons that will allow OPOs to only focus on getting the organ transported, as opposed to also having to find a team to do the recovery as well. This maximizes efficiency and cost and allows greater flexibility with scheduling OR time.
Finally, Gift of Life Michigan would recommend the ability of transplant programs to accept more than one liver at a time for the same recipient to be evaluated before continuous distribution is put into place. We believe late turndowns are resulting in more livers being emergently placed in the OR or after recovery, which dramatically increases the likelihood an organ will go unused, and a life-saving gift wasted.
Whether the medical urgency score in liver allocation should switch from MELD and PELD to OPOM: We support the advancement of an allocation system that ensures equitable access to all waitlisted candidates. Optimized prediction of mortality (OPOM) has been suggested as a more advanced machine learning tool that predicts a candidate’s waitlist mortality more successfully than MELD/PELD. A system that reduces mortality for patients waiting and immediately following transplant would maximize the gifts donated, which we strongly support. The modeling of OPOM also more accurately and objectively prioritized candidates for liver transplant resulting in a significant number of additional lives saved each year. We support a data-driven system that encourages the use of more complex organs for the right recipient.
Transplant Families | 03/14/2023
Transplant Families supports the comments of the OPTN Pediatric Transplantation Committee.
American Society of Transplant Surgeons | 03/14/2023
The ASTS is in support of the challenging work being undertaken by the UNOS Liver/Intestine Committee as it works to try to develop a continuous distribution system for liver and intestines. We are also generally supportive of the attributes the committee is considering. The most complex is related to the distance from the donor hospital. We urge the committee to assess the impact of lung continuous distribution model and then incorporate any lessons learned, before continuous distribution is adopted for other organs. For liver, it will be valuable to first review the impact of the recently implemented Acuity Circle model on geographic disparity and closely examining its impact across the country before moving to another change in geographic distribution via continuous distribution. It will be important that the new policy should learn from the outcomes we have just generated from the change to acuity circles.
The ASTS supports continuing with the use of the MELD/PELD score in the first iteration of the continuous distribution system, as opposed to changing to OPOM, because this will already be an unprecedented amount of change. If we change how we measure medical urgency at the same time as all the other components of the system, it will be hard to determine which parts of the system are leading to favorable or unfavorable outcomes. Given the liver/intestine allocation system just changed to a new system 2 years ago, the opportunity for modeling may be limited, as LSAM will not have the current system data available to use. One additional concern about OPOM is that by prioritizing those with HCC who are at the highest risk of waitlist drop out/waitlist mortality, we may inadvertently prioritize patients who are at risk of post LT recurrence of HCC and thus achieve worse post LT outcomes.
The ASTS supports trying to incorporate a post-transplant survival factor, but we agree with the Liver/Intestine Committee that at present, there is not a reliable post-transplant survival prediction model and therefore the ASTS supports the committee’s decision to not include this at the present time.
Whether the committee should include a factor for height or BSA will depend on the anticipated impact of choosing one versus the other. It is likely that either option may be beneficial, though it is not clear how obesity or massive ascites may impact the calculation of BSA and the predictiveness of this as a surrogate for difficult to match. Patients of short stature with massive ascites may be able to accept larger livers though this is generally not true for patients with obesity.
The ASTS is supportive of highly prioritizing prior living liver donors who subsequently require liver transplantation, and those that are closer to the time of donation should be prioritized even higher. This is anticipated to be very rare.
The ASTS is supportive of consideration of incentivizing split liver in the new system, though the ASTS recognizes the challenges of split liver including increased frequency fatty infiltration of the donor liver and potentially high acuity of the index recipient. The low frequency of split livers may not warrant adding a high amount of complexity to the allocation system. It would be valuable to determine if there are any lessons learned from the Region 8 split liver variance that can be reviewed. Placement efficiency and population density are the most complex components of the new proposed system. It is difficult to justify placement efficiency ahead of disease acuity, yet it is also impossible to allocate across a large portion of the entire US. Importantly, transplant hospitals and donor hospitals and population densities are not evenly distributed. It is important to distribute over a broad enough area so that access and geographic disparity do not worsen in sparsely populated areas, but distributing over large areas may not be necessary in densely population areas under a new system. The ASTS may support a donor quality scale if one was reliable and readily available. In the absence of this, DCD/age of 70 are reasonable donor quality surrogates. Donor steatosis is valuable but not reliably available.
ASTS cannot support or disagree with this public comment update on continuous distribution of liver and intestines as there are no substantial details included. ASTS does feel strongly that OPTN needs to review the actual data on the recent system outcomes on liver allocation/distribution over the last few years to understand how the most recent changes in liver allocation/distribution have affected outcomes, efficiencies, and costs of liver transplantation. OPTN also needs to show the data that becomes available on other organs, such as lung, that may utilize continuous distribution before others to understand if the outcomes achieved were as simulated.
American Society of Transplantation | 03/14/2023
The American Society of Transplantation (AST) offers the following comments for consideration in response to the request for feedback, “Update on Continuous Distribution of Livers and Intestines:”
- At present, the liver value prioritization exercise submitted for response included the following subsets of patients for inclusion in the Analytical Hierarchy Process: pediatric recipients, difficult to match recipients, high medical acuity (i.e., high MELD) recipients, geographically local recipients, prolonged duration of listing recipients, and prior living donors. Additional factors should be considered in the model to improve equity of access. Of particular note, is the need to prioritize livers for patients who are underserved by current policy, including short stature patients. Additional comment was made about potential consideration of risk factors such high cardiometabolic risk and severe obesity, but many felt that these risk factors should be assessed and optimized at the center level rather than prioritized on national allocation strategies.
- Frailty assessments should not be considered as inclusion criteria in national waitlist prioritization. Earlier transplant would potentially benefit certain frail patients, such as those with severe ascites requiring multiple paracentesis; however, frailty has been closely linked with both pre- and post-transplant morbidity and mortality. Frailty measures are often subjective and may vary significantly based on operator characteristics, resulting in introduction of bias into what should be an objective stratification of waitlist mortality. It would be dangerous to include such a measure into candidate prioritization and could potentially serve to limit access to transplant for certain vulnerable populations. If frailty assessments are included, it is essential that objective measurements, e.g., Liver Frailty Index, are factor in to avoid misrepresentation. •Prioritization of long duration of listing should not be considered as a priority for patients awaiting liver transplant alone, but perhaps should be considered in patients who are dual listed for kidney transplant.
- Transition to OPOM could potentially improve some known inequities with the current MELD/PELD system; however, there are concerns about implementing this change concurrently with continuous allocation and without fully evaluating the impact of implementing MELD 3.0. If inequities persist after implementation of continuous distribution, staged implementation was supported with additional modeling to ensure best estimation of effect. Further as OPOM has only been used for adults a plan to expand its use in pediatrics would also be needed. Were there enough adolescents in the OPOM studies to justify their inclusion?
- There are some concerns with the inclusion of post-transplant survival in the model. While inclusion of post-transplant survival in organ allocation would address the precept of “avoiding futility,” it risks introducing additional inequity. At present, all clinical methods of estimating post-transplant survival from pre-transplant metrics are inadequate, especially in the absence of donor metrics (which are not known while a candidate is on the waitlist). AUC analysis on multiple studies has shown most have c-statistic ~0.6, which is barely over the flip of a coin. In addition, inclusion of survival might increase inequity in advanced age liver transplant candidates. Perhaps alternatives of estimated life-years gained or an age-adjusted survival benefit could be considered, but inclusion of this metric in organ allocation remains concerning in the absence of strong evidence regarding its potential effect.
- Living donors should be prioritized like they are with kidney as the number of living donors is increasing.
- The AST suggests further subdividing the hard-to-match group by reason for difficulty to better determine when these patients should receive priority.
- Location of donor recovery should be considered in the proximity metric rather than the donor hospital as the purpose of proximity points is to increase efficiency so the location of recovery is going to determine travel distance, time, and mechanism.
- With this and the other proposals for continuous distribution, it would be important and beneficial to conceptualize evaluation criteria (i.e., objective and measurable criteria by which we can determine the implementation of these new protocols are successful) ahead of their implementation.
American Society for Histocompatibility and Immunogenetics (ASHI) | 03/14/2023
This proposal is not pertinent to ASHI or its members.
OPTN Transplant Administrators Committee | 03/14/2023
The Transplant Administrators Committee thanks the Liver and Intestinal Organ Transplantation Committee for their efforts in developing this request for feedback.
The transplant community is looking forward to seeing progress on liver continuous distribution and encourage all members to participate in the liver prioritization exercises.
Recommendation to develop a patient pamphlet similar to what was done in 2005-2006 for the previous lung distribution changes. This was helpful to provide patients with information about the allocation changes and how the new system might impact them. This should also be available in paper and online versions.
NATCO | 03/14/2023
NATCO thanks the Liver and Intestinal Transplant Committee for all the work that has already gone into identifying and selecting attributes that promote a fair and equitable system of allocating organs through continuous distribution. NATCO commends the Committee for its attempt to design a system that eliminates “hard boundaries” and focus on a more patient-centric system that considers multiple new attributes with the goal of promoting equitable access to those in need. NATCO agrees with the Committee’s selected attributes because they align with the goals of optimizing organ utilization and minimizing organ discards. In the medical urgency category, patients with a higher status and/or MELD/PELD should be one of the highest weighted factors considering patients with a status 1A are at a high risk for mortality if they do not receive a transplant within 90 days. Additionally, in this same category, certain candidate diagnoses may need to be weighted more heavily than others based on likelihood of mortality within a certain time frame. Keeping equitable access in mind, both attributes in the candidate biology category should be rated and weighted heavily since these are factors that cannot be changed and/or a candidate has no control over. With the current system, transplant centers turn down organs for “size” on a regular basis, but a more precise system could get these candidates more appropriate and timely offers if weighted appropriately. In the patient access category, prior living donors must be prioritized. If they are not, this could potentially deter potential living donors from donating for fear of compromising their own health. Lastly, post-transplant survival should be factored in, but with the caveat of minimizing penalties to transplant centers wherever possible. The allocation operates optimally if fear of accepting organs is lessened and taking risks with the goal of increasing utilization and decreasing discards is promoted.
Region 8 | 03/14/2023
An attendee indicated that she agrees with equity, but there is an absurd implementation cost for this project. An attendee asked how it should account for the knowledge gap between coordinators and candidates and requested the committee provide structured language to help the coordinators in communication with candidates. An attendee inquired about how points will be given to pediatric candidates. An attendees’ institution indicated that it was surprised that C-statistics in the 0.6 range were used to exclude post-transplant models. The member said that the SRTR report, used in the development of lung continuous distribution, indicates the C-statistics from the 5-year survival models were below 0.6. An attendee said that he supports moving beyond mileage as the only consideration after MELD.
OPTN Transplant Coordinators Committee | 03/14/2023
The Transplant Coordinators Committee thanks the Liver and Intestine Committee for their work on this project.
A member commented that after taking the liver prioritization exercise, she didn’t think the “candidate waiting greater than 10 years” was applicable for liver.
A member appreciated the attention to population density since her transplant center is located in Florida and surrounded by water.
A member commented that the optimized predication of mortality (OPOM) model being discussed by the Liver Committee would be a big shift from MELD/PELD. It might also be challenging to implement at the same time as continuous distribution and does not currently contain a corresponding OPOM score for pediatric candidates. A member noted that a lot of resources could be freed up nationally by reducing the number of exceptions.
OPTN Organ Procurement Organization Committee | 03/14/2023
The OPO Committee thanks the Liver and Intestine Committee for their work on this project and offers the following comments.
There was some discussion about the use of population density as part of the placement efficiency attribute and how donor availability or eligible death density also needs to be evaluated as this project moves forward.
Concern that distance alone is being used to determine placement efficiency. For example, with the new lung continuous distribution, an East Coast OPO had five of the first ten candidates on a lung match run located on or near the West Coast of the United States. While providing equity in access to organs, broader distribution of organs creates logistical challenges for OPOs and increase in non-use rates.
Members agreed that placement efficiency should be give a higher weight within the continuous distribution framework.
Giridhar Vedula | 03/13/2023
I would like to thank the committee for an opportunity to comment on continuous distribution of the liver and intestine. While I believe there is a desperate need to modify her current schema, I would like to ensure that sound medical judgment and data derived concepts are not ignored over subjective value judgments. I would suggest building attributes based on estimated Post transplant survival as opposed to weighted features like distance from donor hospitals. Especially since early data on Machine perfusion on liver preservation suggests equal, or even improved outcomes with longer preservation times.
OPOM shows a lot of promise but has yet to be used in the prospective allocation of liver and should be studied prior to making it an objective attribute among many other subjective attributes in allocation.
Additionally, we need to focus on efficiency of allocation. Currently OPO’s are able to turn down patients and list dive to suit their staffing inadequacies (go to the OR sooner so they don’t have to use travelers) , real or perceived sense of urgency from thoracic teams and single center OPOs that accommodate their own local transplant centers. That form of behavior will negate any attribute driven allocation schema.
James Sharrock | 03/12/2023
The concept as described in the paper has a major flaw. The associated AHP values exercise fails to include post-transplant outcomes as an attribute. As a heart/liver recipient, I have followed the development of Continuous Distribution policy with great interest. The concept of a points-based system designed to eliminate existing hard boundaries is exactly how organs should be allocated. Of particular importance to me, and to virtually all of the patients with whom I have direct or indirect contact, is how the allocation models for each organ treat long-term graft and patient outcomes relative to other attributes. The AHP values exercises utilized by the Lung, Kidney, and Pancreas Committees asked the public to provide their views of this question. Only the Lung Committee has completed a proposal. It has been adopted by the board and is nearing implementation. The results of the lung values survey played a major role in how the Lung Committee chose to allocate lungs. In reports from the committee the outcomes attribute was widely and deeply discussed. Presentations made by the committee focused on the committee’s modeling of various ratios of outcomes to waitlist survival, which found that a 1:1 ratio of post-transplant outcomes to waitlist survival would result in the highest number of projected transplants. The committee chose to use the 1:1 ratio in its proposal. Kidney and Pancreas policy is still in development. The Liver Committee chose to not include an outcomes attribute in their exercise. The purpose of these exercises is to obtain a broad-based view of values. The concept of the continuous distribution development model is that the medical professionals have the skill necessary to determine the applicable science, but their values do not necessarily reflect the values of the broader community. Without feedback from the public on this question, it will be very difficult for the committee to include outcomes as an attribute in their first iteration formula because they would have no valid basis to determine a relative weight. The paper basically acknowledges this by saying the committee will “consider” outcomes, but all indications have been that they have no intent to actually include it in the first iteration. One highly valued benefit of Continuous Distribution is the assumption that it will make future policy changes less time consuming because changes suggested by future results can be incorporated rapidly. It would appear that means faster adjustments of the relative importance of attributes or use of different data for determination of how attributes are measured. Presumably, however, the introduction of an entirely new attribute will be a major change requiring significant data support and policy development. Given the time it will take to complete and implement this first iteration, obtain data based on results, and develop a second iteration of liver CD which includes outcomes as an attribute, it is likely that outcomes will not be included in liver allocation until 2029 or even much later. In a world in which the public has been told post-transplant outcomes would be a factor in organ allocation that is not acceptable. Additionally, Continuous Distribution has been described as a system that has uniformity across organs except to the extent there are organ-specific differences. While there may be differences in the relative importance of outcomes, it is very difficult to see how outcomes can be worth 25% of lung allocation but the community is not even asked what they think for liver allocation purposes. That difference is likely to be a subject for intense community and board discussion at a later point. There is ample time and opportunity for the committee to consider how outcomes can be predicted and to determine the relative value of outcomes predictions to other attributes, and for future public comment on any final proposal, but the committee must obtain community feedback on this issue to provide a valid basis for the remainder of their work.
Anonymous | 03/11/2023
Prior living donor (for kidney and liver) needs to be a trump card factor, placing those individuals above all other recipients. These heroes voluntarily donated, and were intensively screened for initial and prospective good health. Their need represents unusual misfortune or screening failure. EXISTING LIVING DONORS HAVE BEEN PROMISED THIS PRIORITIZATION. Future living donors will be disincentivized if this is one among many factors. These donors graciously provide a higher quality organ than any deceased donor. As a potential recipient, I feel living donors ethically and practically deserve our highest gratitude and priority. Living donors are the area of greatest potential donor growth, PLEASE DON’T SCREW IT UP!
OPTN Ad Hoc Multi-Organ Transplantation Committee | 03/11/2023
The OPTN Multi-Organ Transplantation Committee thanks the Liver and Intestines Committee for their hard work on continuous distribution. As a committee we are generally supportive of the update to continuous distribution the Liver and Intestines Committee has developed. We understand this is difficult and complex work. Some MOT Committee members feel that CMV matching should be considered as a potential attribute.
Region 9 | 03/09/2023
An attendee remarked that the composite allocation score makes the most sense for liver allocation where we try to equate certain pathologies with MELD and instead of having a board to assign MELD, the system could do it. The attendee added they were surprised to see that biliary disease aren’t represented on candidate biology. Another attendee cautioned the committee against using population density as surrogate for donor density, as the two aren’t the same. A member stated that continuous distribution is a reasonable approach for kidney and lung, so it should also be reasonable for livers and intestines.
OPTN Ethics Committee | 03/08/2023
The OPTN Ethics Committee thanks the Liver and Intestine Transplantation Committee for the opportunity to provide feedback on this update. The Committee is supportive of the values prioritization process to rank attributes as determined by participant review and Committee Review. The Committee supports this transparent way of policy creation to maintain the ethical principles of utility and justice.
Also, the Committee is pleased to see the inclusion of points awarded for prior living donors and asks for clear communication to the community about how highly this attribute will be weighted and the Liver and Intestine Committee’s rationale behind this. The Committee should model the prior living donor attribute and determine if increased priority further exacerbates racial and socioeconomic disparities.
More information regarding the Committee’s decision to not include social determinants of health as an attribute within continuous distribution is also important to include in the proposal for the community, as many would be in favor of awarding some points for social determinants of health. Finally, the Ethics Committee suggests the Liver and Intestine Committee elaborate on their thinking about post-transplant outcomes in continuous distribution. Both kidney and lung allocations give points for EPTS, however, in liver, there are no points awarded based on immediate post-transplant outcomes. The white paper does note the unreliability of post-transplant outcome models for liver; however, it seems as though post-transplant outcomes should be considered equally across organs.
Region 5 | 03/03/2023
A member commented that there is a need for ample objective data to support each bracket. In support of the principle of continuous distribution, a member commented that the process for developing guidelines is critical. The member also suggested that the committee consider forming a focus group for both pediatric and adult candidates in order to develop the metrics and factor that need to be measured and utilized. Another member commented that the shift to continuous distribution is a good change. The member inquired how will placement efficiency be determined – will centers that answer donor offers quickly, have fewer reversals, have fewer late turn downs and therefore, be rewarded with more offers?
Michael Marvin | 03/01/2023
The number 1 priority should be efficiency of the system. All other initiatives, while important, will not have the same impact on the overall number of transplanted organs, and reduction in discards, as efficiency of the system.
Region 10 | 02/28/2023
Members in the region offered several suggestions for the committee to consider as they continue towards Continuous Distribution. An attendee who was heavily involved in developing Continuous Distribution for Lung suggested that the Liver community should apply future proposed attribute weights to their patient population to see if the new allocation score makes sense. If things seem off base, then the committee will have time to adjust attribute weights before finalizing a proposal. Another attendee noted that moving away from MELD will allow for anatomical differences in the patient population. The committee should add attributes for various binary anatomical differences like portal vein thrombosis, re-transplantation, or hepatocellular carcinoma. It may be more difficult to accommodate other attributes that are more complex and not a yes/no answer. Another attendee added, as the community transitions to a continuous distribution system it needs to take into consideration utilization and placement efficiency along with the added cost of organs being transported across the country. In addition, there was a request for more of a financial analysis as costs have gone up substantially because organs are flying more, and local offers are leaving the DSA. Another attendee noted support for utilizing other attributes, especially population density, along with deleting attributes for post-transplant survival. Universally, the OPTN needs to shift allocation policies to find ways to rule organs "in" vs. ruling organs "out". Another member added the committee needs to remember that transportation is fluid and affected by the time of day, weather, and access to airports. Lastly, an attendee recommended the OPTN provide programs the opportunity to look at their individual lists with currently policy and the new proposed Composite Allocation Score, prior to public comment. That way programs will be able to see how it affects their list before it gets fully implemented. Then additional modeling can be done if there are unintended consequences.
Anonymous | 02/27/2023
I am very appreciative of the considerable work invested in bringing our transplant community to Continuous Distribution of Livers and Intestines. My concerns relate to how Continuous Distribution does or does not satisfy the Final Rule concerns regarding organ allocation in that it be based on sound medical judgement, seek to achieve the best results, seek to avoid wasting organs and seek to avoid futile transplants. The development of Continuous Distribution of Livers and Intestines does not include post-transplant survival data and is based on value(s) exercises, ratings, prioritizations, weighting, and opinions to pursue Equity. Continuous Distribution should be based on sound medical judgement (peer-reviewed medical literature) not values, weightings, sentiments, and opinions. Continuous Distribution must include post-transplant outcomes measures (patient and/or survival) otherwise we will simply be measuring how well our results match our allocation system based on our collective subjective values of Equity. The allocation performance goal(s) or indicator(s) should be objective and measurable.
Region 3 | 02/24/2023
During the discussion one attendee commented that there is a compelling argument to be made for continuous distribution. They added that one challenge of the system is that it is not easy to understand by patients and professionals. Another attendee commented that Optimized Prediction of Mortality or OPOM seems like a good concept.
OPTN Pediatric Transplantation Committee | 02/23/2023
The OPTN Pediatric Transplantation Committee thanks the OPTN Liver and Intestine Transplantation Committee for the presentation and the opportunity to provide feedback. The Committee is highly supportive of the transition to continuous distribution but identified some considerations for the Liver and Intestine Transplantation Committee to keep in mind. First, the Committee suggests changing "candidate age" to something that clarifies that the attribute is aimed at providing pediatric priority, as this may be confusing to the community. Second, the Committee recommends the inclusion of patient advocacy groups as well as pediatric specialists beyond those who serve on the Liver-Intestine Committee throughout the policy development process to ensure appropriate pediatric consideration. Third, the Committee notes that if OPOM is to be used instead of PELD for determining medical urgency, it will be critical to ensure that there is a pediatric-specific OPOM that is derived from pediatric and adolescent data – and includes key conceptual updates that have just been approved for PELD, including calibration of a “pediatric OPOM” score to age-adjusted waitlist mortality rates predicted by the “adult OPOM” scores and use of continuous instead of categorical variables whenever possible. We support the inclusion of priority for “initiating a split liver transplant” – and hope that the committee will develop a definition that considers recipient, donor, and potentially center factors to accurately identify offers that are actually creating 2 transplants from 1 liver. There was some concern for center-level attributes, such as split-liver utilization, potentially disadvantaging candidates for center practices that are out of their control; transparency, education, and collaboration with patient advocacy groups will be important critical to address this. In general, the Committee supports continuous distribution and appreciates that the Liver-Intestine Committee is carefully considering the impact on children – both of pediatric priority and on balancing that with other priority attributes – throughout the CD development process.
Region 2 | 02/21/2023
One attendee noted that placement efficiency should be the highest weighted attribute. There has been a large increase in workload and overall efficiencies with liver acuity circles, and continuous distribution is an opportunity to address those issues. Another attendee added that geographical differences across the country have different effects on allocation. This attendee encouraged the OPTN to consider that distance is not the only aspect of placement efficiency being considered by the committee. Transplant hospital density, along with population density, are very important attributes for the committee to consider. Another attendee noted that local organ availability is the most efficient. One attendee suggested that the committee should consider consulting with a geographic sciences expert to analyze overlapping geographic parameters through computer modeling. Lastly, another attendee stated that the goal of the project should be to maximize the number of successful transplants and the committee should assess the impact of attribute selection on the transplant rate.
Region 4 | 02/21/2023
Two attendees commented that this system is very complicated and adds more complexity to an already complex system. They added that the financial impact of changing the system should be considered and weighed against the benefit. One attendee commented that the community should re-evaluate the time frame placed on the prioritization exercise and development of a new system until the impact of the Acuity Circle system can be evaluated. Another attendee commented that the attributes and weighting will be critical to determine the success of continuous distribution. Another attendee commented that replacing MELD/PELD with OPOM in the continuous distribution without prior evaluation of OPOM as an independent measure of candidate priority would complicate the development of the system. They recommend independently evaluating OPOM prior to considering it for use in continuous distribution. Another attendee commented that the community needs to exercise a thoughtful approach and balance between developing a comprehensive framework to prioritize patients and also not to create something that is too complex for people to understand or implement.
Anonymous | 02/02/2023
I agree with this.
Steven Weitzen | 01/29/2023
I support the initiative.