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Establish Continuous Distribution of Lungs

eye iconAt a glance

Current policy

The current system allocates lungs by placing candidates into categories that are arranged by priority. Sometimes a candidate’s category places them on the side of a hard boundary that would prevent them from appearing higher on the match run. Continuous Distribution is a proposed allocation system that considers multiple patient and donor attributes all at once with an overall score. This overall score includes medical urgency, patient outcomes, biological make-up, and other candidate factors and efficiency of organ placement.

Learn how it works

A closer look at the proposal

Presentation to the OPTN Patient Affairs Committee about how continuous distribution works


View presentation

Proposed changes

  • Remove current classification system and replace with a lung composite allocation score which is comprised of the following attributes:
    • Post-Transplant Outcomes, or how long a patient is expected to live after receiving a transplant
    • Medical Urgency, or how long a patient is expected to live without receiving a transplant
    • Biological Disadvantages, for patients who are medically harder to match which includes candidate blood type, sensitization, and height
    • Patient Access, for patients under the age of 18 and patients who are prior living donors
    • Placement efficiency, or the resources required to match, transport, and transplant an organ which includes both travel efficiency and proximity efficiency
  • Each attribute has a rating scale, which will determine how many points a candidate receives for each
  • Each attribute has a relative weight. The total weights add up to 100
  • These points combine into a total score for the candidate
  • With every organ offer, a candidate receives a new Composite Allocation Score (CAS), which is used to rank the candidates

Anticipated impact

  • What it's expected to do
    • Remove hard boundaries that prevent candidates from being prioritized higher on the match run
    • Reduce waitlist deaths
    • Decrease the number of lungs that are transported via airplane
    • Increase transplant opportunities for pediatric candidates
  • What it won't do
    • Change allocation of other single organ transplants


  • Attributes
  • Weight of attributes
  • Multi-organ allocation
  • Exception review process

Terms to know

  • Composite Allocation Score (CAS): The total number of points assigned to a candidate on the wait list, which would determine their rank on a match run.
  • Rating Scale: Method used to calculate number of points awarded to candidates for each attribute. For example, if everything else is equal, should a candidate with twice as much medical urgency as another receive twice as many points? Applying the rating scale to each candidate’s information and combining it with the weight of the attribute results in an overall composite score for prioritizing candidates.

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Provide feedback

eye iconComments

OPTN Organ Procurement Organizations Committee (OPO) | 09/24/2021

The OPO Committee appreciates the opportunity to provide feedback on the Lung Committee’s Continuous Distribution proposal and provides the following comments: One member shared that multi-organ allocation policy is confusing, with both OPOs and transplant centers struggling to understand the requirements in every situation. Another member remarked that there would likely be pushback from liver programs with not allowing status 1 or high model for end-stage liver disease (MELD) score potential recipients to receive offers ahead of lung-liver candidates. The member continued that this is particularly critical with only lung initially moving to a continuous distribution system, with liver still in geographic circle-based distribution. A member asked about the difference between placement and travel efficiency, and remarked that a combined 10 percent weight didn’t seem sufficient. The member asked what consideration was given to the infrastructure available to facilitate and transport broader sharing, as well as to the impact on getting donors to the operating room, total recovery time, and teams’ ability to travel. The Chair of the Lung Transplantation Committee noted that broader sharing impacted different parts of the country differently across both OPOs and transplant centers, and pointed out that the OPTN does not collect data on travel and logistics. Dividing efficiency into travel efficiency, the number of miles between candidate and donor hospitals, and placement efficiency allows allocation to capture all the ways allocation can be inefficient in order to closely monitor the effects of the change. Another member expressed concern that monitoring transportation following a policy change instead of providing data on potential impacts to efficiency is insufficient. The member remarked that travel and transport systems are already stressed, and that it has become very difficult to get flights to procure livers or even have livers shipped. The member continued, asking why this data isn’t currently being collected. The member commented that it is inadequate to create policy without sufficient data, and that it creates an unfair burden on OPOs and transplant centers when there isn’t transportation available. Another member expressed concern that the current infrastructure may not be able to support further broader sharing.

Region 1 | 09/24/2021

Region 1 sentiment: 3 Strongly Support, 3 Support, 2 Neutral/Abstain, 0 Oppose, 0 Strongly Oppose. Comments: Overall the region supports the proposal. A comment was submitted in support of this proposal, saying it is extraordinary work. One member commented that the MPSC is pulling back from needing longer term outcomes, in regards to using 5 year post transplant outcomes for the composite allocation score. Another attendee asked if the committee had considered giving a specific group or category an “off the charts” number of points, similar to the points given to 100% sensitized kidney patients.

OPTN Pediatric Transplantation Committee | 09/24/2021

The Pediatric Committee thanks the OPTN Lung Transplantation Committee for the opportunity to review their public comment proposal. The Committee provides the following feedback: The Committee appreciates that the proposed weighting of factors in the Composite Allocation Score aligned closely with the priority weighting of the entire stakeholder community, as assessed in the AHP prioritization exercise. The Committee agreed that this is a great start in the transition to continuous distribution for lungs. One of the concerns the Committee expressed was whether the priority points children may receive for height, pediatric priority, and possible biological disadvantages would negate the fact that the lung allocation score (LAS) doesn’t work well for children under the age of 12. The Committee suggested that, in regards to the LAS score for candidates under 12 years old, the post-transplant outcomes score should be re-evaluated over time since it will be the same score given to all lung candidates under 12 years old.

Region 6 | 09/23/2021

Region 6 sentiment: 2 Strongly Support; 17 Support; 4 Neutral/Abstain; 0 Oppose; 0 Strongly Oppose. Comments: An attendee observed payers look at overall costs based on individual candidates; and this could increase variation across the country; the committee should consider this in their proposal.

Region 8 | 09/22/2021

Region 8 sentiment: 5 strongly support, 12 support, 6 neutral/abstain, 1 oppose, 0 strongly oppose. Comments: Region 8 generally supports this proposal with one opposition. A member commented that he supported that the Lung Committee decided to recognize living donors regardless of what organ the living donor donated. A member suggested to be mindful of the adolescent population because the SRTR report suggests that adolescent organs will be allocated less to the adolescent groups. A member asked for clarification on the multi-organ allocation aspect. The member stated that it appears the OPO can offer the heart or liver with the lung if they have a score of 28 – the member asked if this was regardless of what the heart and liver lists look like.

Transplant Administrators Committee | 09/21/2021

The Transplant Administrators Committee (TAC) appreciates the opportunity to comment on this proposal. TAC supports this proposal and particularly appreciates the detailed explanation of how the composite allocation score was developed. TAC also supports the proposed changes to multi-organ allocation since the broad discretion that organ procurement organizations (OPOs) have in multi-organ allocation today can lead to inconsistency in practice and frustration between transplant centers and OPOs. TAC acknowledges the challenges that OPOs face in managing heart-lung allocation and supports clarification of associated policies. Finally, with regard to the proposed changes to the exceptions process, TAC believes that five days is sufficient time for reviewers to vote on exception requests.

Inova Fairfax Hospital | 09/17/2021

On behalf of the Inova Lung Transplant Program, we fully endorse the proposed change to the lung allocation system. We believe this will result in the more equitable distribution of lungs to those most in need. We are particularly happy that projected 1 year post-transplant survival has been replaced with projected 5 year survival. We agree with all the factors accounted for within the new proposed model and commend the committee for their efforts in putting this together.

Region 7 | 09/15/2021

Region 7 sentiment: 7 strongly support, 9 support, 3 neutral/abstain, 0 oppose, 0 strongly oppose. Comments: One attendee recommended the OPTN consider a higher point allocation for travel efficiency and proximity efficiency because the logistical challenges of moving teams and organs are going to increase and asked if there is a way to estimate how much travel will increase. Another attendee commented that the proposal eliminates ABO identical/compatible prioritization and hard geographic boundaries. The proposal also enhances access for candidates with biological barriers like sensitization and small stature; and rebalances medical urgency and post-transplant survival. This could disproportionately impact small programs and regions with less population density. Other attendees expressed that overall the proposal favors broader geographic sharing, this will increase travel time, which may be easier for large programs with robust recovery teams to manage. This will also make it more difficult for candidates with low medical urgency (i.e. low LAS in current system) to get access to good quality donors, since the current allocation system gives low LAS candidates access to donors before they get offered to sicker patients in the next allocation classification. One attendee commented that combined, these trends may make it harder for smaller, low-risk programs to transplant, which could cause these programs to shut down. This may not be a problem in metropolitan areas with multiple lung programs but may be a program in more rural areas with patients who can't travel out of state for health care. Another attendee noted that while modeling is essential, the OPTN cannot model changes in transplant center donor selection practices. Inevitably, these practices will change as the result of such a dramatic alteration in the allocation system. Therefore, it will be hard to predict the presence and magnitude of unintended consequences of this proposal. An attendee recommended that with the incorporation of CPRA utilization, consider require sharing of donor serum for crossmatch, similar to the process for kidneys, when requested by transplant centers to further support access to transplant. One attendee suggested that the OPTN should consider how to mitigate any resulting inefficiencies and model the impact continuous distribution will have on donation for all organs.

Anonymous | 09/15/2021

A few thoughts: 1) This is a great leap forward for organ allocation and provides a solid framework for the OPTN to use moving forward. 2) I am curious how this would change were the allocation to change depending upon donor factors. For instance, the current lung system is different for pediatric vs adult donors. 3) In thinking of efficiency, could we do more to allocate organs to candidates most likely to accept them? From an OPO perspective, we don't think about cost and distance only. We also think about the number of offers and the time to placement. This is really critical when an organ needs to be reallocated after a late turn down. 4) I am glad to see the new benefit for prior living donors. While rare, this is the right thing to do.

Region 9 | 09/14/2021

Region 9 sentiment:  1 Strongly Support; 7 Support; 4 Neutral/Abstain; 0 Oppose; 0 Strongly Oppose. Comments: Region 9 overall supports this proposal. A member stated they believed that patients listed for both heart and lung should receive more priority. The member also noted that pediatric lung transplant is rare and questioned the need for the changes related to pediatric lung transplant.

Region 3 | 09/10/2021

Region 3 sentiment: 2 strongly support, 9 support, 4 neutral/abstain, 0 oppose, 0 strongly oppose. Region 3 supported this proposal. One attendee commented they favor giving prior living donors more weight, although living lung donors are rare. Another attendee supported the proposal but stated the policy will change the profile of the patients being transplanted and will require the SRTR to develop a new risk stratification for the patient population. The attendee added they believe this will unlikely change regional transplant rates because the location of organs is not necessarily an important factor for large volume centers. This attendee also questioned if, relative to exceptions, this is a permanent, "indefinite" exception applicable in all situations, especially when clinical issue may improve in a couple of weeks with medical management.

David Homann | 09/10/2021

I think the proposed allocation system is fair and takes into consideration several factors that are currently overlooked. I also believe the proposed system will reduce the wait time for those critically in need of lungs. I feel blessed to have received my lungs and hope that others in need can be equally blessed.

Region 2 | 09/10/2021

• Region 2 sentiment: 7 Strongly Support, 17 Support, 4 Neutral/Abstain, 0 Oppose, 0 Strongly Oppose • Comments: Members of the region supported the proposal. A few members had comments about post-transplant outcomes at 5 years. Five years could be challenging, but 3 year post transplant outcomes could be more attainable. One member noted that 3 year post transplant outcomes are better understood and modeled by the SRTR and these outcomes are reported publicly. It was also noted that clarification is needed for multi-organ patients and how the proposed model will impact how lungs (vs. the non-lung organs) are prioritized for allocation. Additionally, information on whether ECMO Bridge will be incorporated into waitlist and post-transplant mortality models is needed. Another member disagreed with the LAS deprioritizing of prior living donors. Although rare, such candidates should be given priority similar to pediatric candidates. It was also suggested that there should be a sliding scale for pediatric priority; there is not much difference between an 18 year old and a 20 year old.

Living Donor Committee | 09/09/2021

The OPTN Living Donor Committee thanks the OPTN Lung Transplantation Committee for their efforts in developing this proposal and the opportunity to comment. The Committee applauds the proposal’s inclusion of prior living donor priority as a new attribute of lung allocation and strongly supports providing PLD priority for all living donors. The Living Donor Committee has discussed the prior living donor priority question at length and concurs with the Lung Committee's conclusions that prioritizing prior living donors is both medically and ethically justified. We further concur with the Lung Committee's discussion of and conclusion about "sound medical judgment" in connection with this issue that is so important to living donors, their families, and the transplant system. Living donors make a selfless decision to put their health at risk to improve the life of another human being. Though living donation is relatively safe, there is still intrinsic risk associated with organ donation as outlined in OPTN living donor policy, and a lack of systematic collection of data about long-term outcomes. Additionally, as the practice of living donation grows, the Committee recognizes the potential for still unknown risks to be associated with donation. Living donors contribute to the transplant system by donating to one wait listed patient and in doing so, enable transplantation of another waitlisted patient when a deceased organ next becomes available. The Committee supports the societal value of reciprocity to make a donor whole and sending a message to the public that the system values living donors. Additionally, PLD priority offers support and assurance to the donor and the donor’s families that the system will take care of them should they ever need a transplant. The Committee strongly supports adding PLD Priority to lung allocation and providing the same level of priority to all prior living donors as proposed.

Anonymous | 09/02/2021

I think kids should be given the highest chance of receiving a gift. Then by need and health of recipient . Post is all up to the recipient and how they protect that gift of life

Anonymous | 08/30/2021

I know that the committee has a lot of information and considerations to take in for this policy. What I think is important. 2yr survival—This makes better ethical sense with the ultimate gift of life. Lets do our best to keep our lung transplant patients going a longer period of time. Candidate biology- Lung that fit into one patient may not be suitable to anyone on else on the list. Lets make sure that size is taken into account and PRA HLA avoids. Efficiency- Time flying to donor hospital, time transporting, ischemia time. All matters. Proximity matters.

Region 5 | 08/30/2021

Region 5 sentiment: 8 strongly support, 10 support, 10 neutral/abstain, 0 oppose, 0 strongly oppose. Region 5 supports the proposal to Establish the Continuous Distribution of Lungs. A member questioned why there needs to be a weight given for travel efficiency and proximity – the member believed that weighted just the geographic distance is sufficient. Another member supported the proposal but was surprised to see the one-year wait list factor. The member believes that if a patient can wait one year for the transplant then the patient doesn’t have an urgent need for the transplant. A member suggested that outcome measurement should be expanded to five years post-transplant. A member suggested that medical urgency should be weighted more than just 25 points. A member stated that it’s important to acknowledge and utilize other groups that focus on data and modeling to help make decisions – for example, to look at optimal level of priority to give attributes like cPRA and make sure there aren’t unintended consequences. A member suggested to think about center effect and center specific metrics that may influence allocation policy. A member pointed out that since many transplant centers do not enter unacceptable antigens for lung recipients, the modeling for cPRA may not be accurate. The member suggested using kidney cPRA data to do the modeling. A member suggested to consider higher points for supersensitized (>90% CPRA) candidates – to consider sensitization (at least >90% CPRA) status factored for waitlist mortality and post-tx outcome points. A member stated that they agree that post-transplant outcomes should be a part of the score and that the value for a listed patient should be the center data rather than the average national data. A member supported the proposal but pointed out that post-transplant survival scores, for pediatric candidates, should be re-evaluated over time (potentially every 3-5 years).

Region 4 | 08/27/2021

5 strongly support, 13 support, 2 neutral/abstain, 0 oppose, 0 strongly oppose. Region 4 supported this proposal. One attendee commented OPOs should have discretion when allocating multi-organs as they increase the number of DCD donors and situations with resources and logistic restraints. Having discretion without running into policy constraints is important to maximize the donor gift. Any flexibility for OPOs around a cutoff point is worth some serious consideration. Another attendee stressed the importance of monitoring the system once implemented to make sure the weighting is correct. One attendee commented that proximity efficiency makes sense, but they would be concerned that travel efficiency becomes a slippery slope into cost as a factor for what should remain primarily a clinical decision regarding CAS. Another attendee commented that they particularly like the 1:1 relationship between waitlist death and long-term survival, and use of a longer-term survival component than one year. One attendee commented that they are excited to see this work. They went on to comment that as we seek to maximize lung placement, this appears to improve the opportunity to get to the patient most in need while providing reasonable balance of the logistics, travel, and timing. Finally, an attendee commented that they support the CAS and it is a major advance over LAS. They went on to recommend the committee consider changing "height" to "lung volume."

dawn freiberger | 08/25/2021

Hi, I am mostly in agreement with this proposal. My only concern is the aspect of long term survival benefit as being part of the consideration. It is very difficult to predict long term survival in this population. If a center opts to list a patient, they have likely taken this both short term and long time survival into consideration to the best of their ability. There is so much that goes into a patients outcomes aside from just medical issues such as adherence, social issues, etc. These considerations are not part of the LAS system because they are subjective, and unpredictable as are many of the medial issues. Hopefully the individual transplant programs consider all of these issues along with medical aspects before deciding to move forward with listing a patient. thank you

Andrew Flescher | 08/19/2021

This was a detailed, clear paper and I appreciate the substantial thought which went into it. The committee did not punt, but came down with clear articulation of how attributes should be weighted and why. It caught my attention, as I am sure it did many, that medical urgency now carries the same weight as post transplant outcomes, whereas before it carried double. My concern is that this might (1) exacerbate hardships experienced by already vulnerable populations, e.g., those in the most dire straights medically (which is a population which historically overlaps with disadvantaged or underserved groups) and (2) provide further impetus for practitioners to engage in outcomes-based, or "stats-driven" medicine. A more minor concern is that this move might also induce gaming of the system, despite efforts to be transparent. From double to equal seems to be a big leap. Perhaps, therefore, more justification than currently appears should go into explaining the proposed modification. I am especially interested in the extent to which this move was based on community feedback. Was the move made because of its feedback, or despite it? If the latter, on what other basis?---Andy Flescher, Vice Chair of the Ethics Commitee

Anonymous | 08/13/2021

It appears that this proposal puts pediatrics at the top of the list each and every time. Has there been any national survey or discussion related to pediatric patients being first in every line? I'm not saying I' against it, I'm just asking the question, and to be transparent, feel the question should be asked before such a proposal is passes. Again, list the Continuous Distribution of Kidney & Pancreas, this is extremely complicated to understand because of so many factors. Being able to explain it to patients so they understand is critical. Transparency in organ distribution is iperative.

PADV | 08/10/2021

It would be helpful to see what a test match run would look like under the proposed weighting. With only 10% of points allocated to efficiency, one may estimate that a donor match run from the east coast could be populated now by a larger number of centers from across the entire US ( vs the number within the 500nm radius from the donor hospital currently). This alone will cause inefficiencies in the organ offer process particularly if transplant centers do not utilize current screening criteria effectively. The list may be saturated with patients for whom the tx center is truly not interested in donors from a far distance and may have other medical comorbitites that are incompatible with their recipient. Screening filters for thoracic organs are currently inadequate and may not offer a transplant center the granular information to effectively screen donors. Traditionally these center and patient screening tools are set to the widest parameters. Better screening tools and rules requiring their utilization need to be developed to advance this policy goal. Simply thinking that centers will adapt and utilize these tools voluntarily is inconsistent with historical practice and needs to be addressed. Also under this weighting consideration outlined in the policy high soring candidates will be entertaining multiple organ offers now simultaneously. This is good for an individual candidate but needs to be weighed against the potential detriment of the overall system. We have experienced with other broader organ sharing, frequent late organ declines by transplant centers and frequent reallocation of organs. The case time for organ donation has doubled since 2008 from a median of 24hrs to currently lasting 48hours. Allocation policy that makes the matching of donors and recipients more complicated by adding more centers into the mix needs to be balanced with providing the OPOs the rules and the tools to make the process more efficient. Policies around acceptance of only one organ per candidate and defining the terms of acceptance of an organ need to be addressed prior to the implementation of any new allocation policy. We are fully supportive of the continuous distribution model but OPOs desperately need state of the art tools and transplant center accountability in acceptance behavior to make the system more efficient. The process of offering and accepting organs needs desperate overhaul to allow us to be better stewards of these precious gifts. I urge the committee to ensure these rules and tools are in place prior to any policy implementation and not just a future promise.