Updated Cohort for Calculation of the Lung Allocation Score (LAS)
At a glance
What is current policy and why change it?
OPTN lung allocation policy for candidates 12 years and older uses the Lung Allocation Score (LAS) as a factor that impacts priority in organ offers. The data used for the score has not been updated in over 10 years. Additionally, some factors used to calculate LAS do not help predict waitlist or post-transplant survival and should be removed from the calculation.
Updated Cohort for Calculation of the Lung Allocation Score
Dr. Erika Lease, Chair of the OPTN Lung Transplantation Committee, reviews the Updated Cohort for Calculation of the Lung Allocation Score policy proposal.
Terms you need to know
- Lung Allocation Score (LAS): In the OPTN lung allocation system, every lung transplant candidate age 12 and older receives a lung allocation score. The LAS is used with blood type and the distance between the candidate and the donor hospital to determine priority for receiving a lung transplant. The score is made up of factors that help determine a candidate’s waitlist urgency and post-transplant survival.
- Waitlist Urgency:A candidate’s risk of death if they do not receive a transplant.
- Post-Transplant Survival: Likelihood of recipient to survive for one year after receiving their organ.
What’s the proposal?
- Update the patient population data used to determine the LAS to include candidates and recipients from March 1, 2015 to March 31, 2018
- Remove factors that no longer help predict waitlist or post-transplant survival
What’s the anticipated impact of this change?
- What it’s expected to do
- Update the data to reflect more recent patient populations
- Provide up-to-date LAS data to inform the Lung Transplantation Committee’s project to develop a new allocation system for lungs
- Change some candidates’ LAS to better reflect their need for transplant
- What it won’t do
- Will not change data collection elements
Themes to consider
- Potential for factors used in calculating LAS to become more or less important
- How often patient population data should be updated
Sponsoring Committee: Lung Transplantation
Strategic Goal: Improve waitlisted patient, living donor, and transplant recipient outcomes
Sam Dey | 10/01/2020
It's absolutely necessary to adjust the rules based on impact from COVID-19. Thank you.
Region 11 | 10/01/2020
Region 11 vote: 2 strongly support, 7 support, 11 neutral/abstain, 0 oppose, 0 strongly oppose. No comments
Cystic Fibrosis Foundation | 10/01/2020
October 1, 2020 Erika Lease, MD Chair, Lung Transplantation Committee Organ Procurement and Transplantation Network United Network for Organ Sharing 700 N 4th Street Richmond, VA 23219 RE: Updated Cohort for Calculating the Lung Allocation Score (LAS) Submitted electronically at optn.transplant.hrsa.gov. Dear Dr. Lease: On behalf of the Cystic Fibrosis Foundation and the below signed individuals of the CF Lung Transplant Consortium, we write in response to the OPTN/UNOS Public Comment Proposal, Updated Cohort for Calculating the Lung Allocation Score (LAS). Updating the Cohort is Not Enough – the LAS Model Must Be Revised: We appreciate that UNOS has recognized the importance of updating the LAS as part of the transition to the continuous distribution allocation scheme for lungs. The LAS is so critical to the organ allocation process that the Committee would be remiss in not making the necessary updates if it is to be used as a core measure in this new model. It is critical that all attributes used in the composite score under the continuous distribution model are as appropriately reflective as possible in measuring the factors they are designed to assess, and the LAS is no exception. While we appreciate that UNOS has proposed using more up-to-date data for calculating the LAS and removing variables that are a poor fit for the model, we urge UNOS to go further. UNOS has promised in the past to review the LAS as new data emerges and revise it as appropriate in a timely manner. However, LAS reforms remain minimal despite evidence that further adjustments are needed to decrease waitlist mortality and reduce arbitrary biases in the existing scoring system. A paper published last year using merged data from the Scientific Registry of Transplant Recipients and the CF Foundation’s patient registry demonstrated that the LAS fails to account for critical variables reflecting waitlist mortality for individuals with CF and COPD. This data demonstrates that the LAS, as it stands, does not identify those most likely to benefit from transplant. However, this data has yet to be acted upon in full by UNOS. With the addition of a few variables, the LAS would better predict the risk of mortality on the waitlist, which would in turn make the model a more useful tool in accomplishing the goals in the Final Rule. We are further concerned that despite the updated cohort, the model for calculating the LAS uses the same variables selected from the previous update to the LAS. This is a methodologically invalid approach, as it assumes that the model will continue to hold despite important differences between the two patient cohorts. It is critical that UNOS reassess the model in full along with this update to the data being used to calculate the LAS to ensure that the model is accurate and predictive of transplant need and benefit. We would additionally like to express concern with removing forced vital capacity (FVC) and diabetes as variables from the score calculation for expected waitlist survival based on data analyzed from the new cohort. While we understand that the goal of this update was to remove unnecessary or counterproductive variables from the LAS based on the new dataset, these variables may have bearing for patients with CF seeking transplant. We ask UNOS to carefully consider how removing these variables may impact estimates of waitlist survival within this patient population. UNOS Must Revise the Benefit Component: As an important component of the continuous distribution model, post-transplant survival should be accurate and predictive of transplant benefit. However, the one-year survival measure currently accounted for through the LAS does not accurately reflect how beneficial a transplant is for any given patient. It is unlikely that people undergo lung transplantation with the aim of only surviving for one year. Instead, we should be using endpoints that are more reflective of transplant success and patient wishes. We therefore urge UNOS to move away from use of one-year survival to either three- or five-year survival as part of the current plans to revise the LAS in preparation for the change to continuous distribution. Changes to the LAS Should Be Made Immediately: We would like to see UNOS address all needed changes to the LAS as soon as possible rather than waiting for certain changes to the LAS to be carried out in conjunction with the implementation of continuous distribution for lungs or at a date following implementation of the new allocation framework. Failure to more thoroughly update the LAS will do a great disservice to those patients who are dying unnecessarily while awaiting transplant. We cannot wait until all organs have transitioned to continuous distribution in order to make these important changes. Background on Cystic Fibrosis and the Foundation: Cystic fibrosis (CF) is a rare genetic disease that affects over 30,000 people in the United States. In people with CF, a defective gene causes a thick buildup of mucus in the lungs, pancreas and other organs. In the lungs, the mucus obstructs the airways and traps bacteria leading to infections, extensive lung damage and eventually, respiratory failure. Over 280 people with CF received transplants in 2018, the majority of which were lung transplants. However, some people with CF also may require liver or kidney transplants due to the disease. In order to address the needs of people with CF living with advanced lung disease, as well as those considering transplant, the CF Foundation launched the Lung Transplant Initiative in 2016. Through this initiative, the Foundation is working to improve and standardize the care received by people with CF for whom transplant is an option and to find solutions to barriers that may adversely impact a person with CF’s chance of receiving a donor organ. Conclusion: We are pleased to see UNOS take steps to revise the LAS. However, we are concerned that maintaining a singular focus on the change to continuous distribution without simultaneously addressing any and all arbitrary measures and biases in the existing LAS model will be a major disservice to patients on the waitlist. We urge UNOS to take immediate further actions to reassess and revise the LAS in order to ensure continuous distribution provides the maximum benefit to patients seeking lung transplants. We are happy to serve as a resource and look forward to working alongside OPTN/UNOS in the future on this issue. Sincerely, Albert Faro, MD Vice President, Clinical Affairs Cystic Fibrosis Foundation CF Lung Transplant Consortium Members: Kathleen Ramos, MD, MSc Assistant Professor of Pulmonary, Critical Care, and Sleep Medicine University of Washington, Seattle Ramsey Hachem, MD Professor of Medicine, Lung Transplant Program Medical Director Washington University School of Medicine Joe Pilewski, MD Associate Chief, Division of Pulmonary, Allergy & Critical Care Medicine University of Pittsburgh Medical Center Courtney Frankel, PT, MS Research Program Leader Duke University Medical Center Matthew Morrell, MD Medical Director, Lung Transplant Program University of Pittsburgh Medical Center Laurie Snyder, MD, MHS Associate Professor of Medicine, Pulmonary Allergy & Critical Care Medicine Duke University School of Medicine Stephen Weigt, MD Associate Professor of Medicine, Pulmonary and Critical Care UCLA Medical Center Christian Merlo, MD, MPH Associate Professor of Medicine and Epidemiology, Division of Pulmonary and Critical Care Johns Hopkins University School of Medicine Jagadish Patil, MD Assistant Professor of Medicine, Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine University of Minnesota Matthew Hartwig, MD, MHS Associate Professor of Surgery with tenure Duke University Health System Stuart Sweet, MD, PhD Professor of Pediatrics, Division of Allergy, Immunology and Pulmonary Medicine Medical Director, Pediatric Lung Transplant Program Washington University School of Medicine in St. Louis Steven Hays, MD Medical Director, Lung Transplant Program University of California San Francisco Jason Christie, MD, MS Chief, Pulmonary, Allergy and Critical Care Division Penn Medicine Isabel Neuringer, MD Associate Medical Director, Lung Transplant Program and Adult Cystic Fibrosis Center Massachusetts General Hospital Luke Benvenuto, MD Assistant Professor of Medicine, Center for Advanced Lung Disease and Transplantation Columbia University Medical Center Pali Shah, MD Medical Director, Lung Transplant Johns Hopkins University School of Medicine Fanny Vlahos Cystic Fibrosis Lung Transplant Consortium Patient Representative Erin Lowery, MD, MS Associate Professor of Medicine and Pediatrics, Pulmonary and Critical Care Loyola University Medical Center Daniel Dilling, MD Medical Director, Lung Transplantation Loyola University Medical Center Gundeep Dhillon, MD, MPH Medical Director, Heart-Lung & Lung Transplantation Program Stanford HealthCare
Region 9 | 10/01/2020
OPTN Lung Transplantation Committee: Update Cohort for Calculation of the Lung Allocation Score (LAS) Region 9 vote: 3 strongly support, 10 support, 5 abstain/neutral, 0 oppose, 0 strongly oppose Comments: None
Association of Organ Procurement Organizations | 10/01/2020
The Association of Organ Procurement Organizations (AOPO) supports updating the cohort data utilized for calculating the Lung Allocation Score (LAS). Utilizing the most current cohort will be helpful in assuring accuracy in calculating LAS and thereby getting donor organs to the patients most likely to benefit from the gift of donation.
American Society of Transplant Surgeons | 09/29/2020
The American Society of Transplant Surgeons (ASTS) strongly supports the concept of updating the variables used to calculate LAS based on a more contemporary cohort. We commend the OPTN Transplantation Lung Committee for its efforts to scientifically re-evaluate the most appropriate variables for the calculation. However, we suggest the OPTN should recommend timelines and updates to the cohort sooner than every 10 years. Currently guidelines exist for obtaining LAS exceptions for patients with pulmonary hypertension. We question if those guidelines will be incorporated into the revised LAS calculation as that would appear to be a reasonable adjustment based on current practice. We would support implementation of this proposal before the implementation of the Continuous Distribution changes for two reasons: 1) the move towards continuous distribution is a complex enterprise with the possibility of delays that might be difficult to predict; 2) it would allow an opportunity to assess the effect of changes to the LAS calculation independent of the impact of continuous distribution. The ASTS strongly supports the stated intent of periodically reviewing the impact of the changes and would advocate for continued re-evaluations and updates to the LAS calculation with contemporary cohorts in the future.
Region 10 | 09/29/2020
Region 10 vote: 3 Strongly Support; 11 Support; 8 Neutral/Abstain; 1 Oppose, 0 Strongly Oppose. Comments: No comments
Region 6 | 09/29/2020
Region 6 vote: 7 strongly support; 24 support; 9 neutral/abstain; 0 oppose; 0 strongly oppose. Comments: None
Region 2 | 09/25/2020
Region 2 vote: 7 Strongly Support, 14 Support, 9 Neutral/Abstain, 0 Oppose, 0 Strongly Oppose Comments: No comments
Region 1 | 09/24/2020
Region 1 vote: 4 Strongly Support, 3 Support, 5 Neutral/Abstain, 0 Oppose, 0 Strongly Oppose Comments: No Comments
American Society of Transplantation | 09/24/2020
The American Society of Transplantation supports this proposal, but offers the following comments and recommendations for consideration: This intent of this proposal is to update the variables, coefficients, and probabilities used in calculating the lung allocation score (LAS). An additional goal is the refinement of variables to those that are predictive within the waitlist mortality and post-transplant mortality models. The current iteration of the LAS is based up on a patient cohort that is now nearly 12 years old. The updated cohort for LAS calculation includes candidates and recipients from March 1, 2015 through March 30, 2018. Given that there were substantial changes made in 2008 it might have been instructive to include in the current proposal more information about the effects of those changes? We should have more than ten years of data to consider. For example, in what ways did removal of the FVC, or the addition of cardiac index, affect candidate selection in subsequent years? Several variables were identified as non-predictive due to small numbers of candidates or recipients. Waitlist variables proposed for removal include: obliterative bronchiolitis; lymphangioleiomyomatosis; Eisenmenger’s syndrome; and Bilirubin increase > 50%. Post-transplant variables proposed for removal include: lymphangioleiomyomatosis; creatinine increase > 150%; and Eisenmenger’s syndrome. - Our adult pulmonology representatives noted that the removal of variables due to small numbers of candidates or recipients is reasonable and appropriate. We agree with this change as well as continued collection of data with reference to these variables for future assessment. - Our pediatric pulmonology representatives noted that the removal of certain waitlist variables due to “small numbers” is a statistical practice that is different than the removal of variables because they have been proven to be accounted for by other variables. For example, they are not arguing, that Eisenmenger’s physiology is irrelevant; rather, simply, that they cannot prove whether it is relevant. Given that there might be a delay of ten years or more until there is further significant revision of the LAS, they suggest that we should be open to the possibility that further research will prove the relevance of some of these “orphan variables.” They would expect that allocation could be adapted accordingly to such a contingency (including, for example, another LAS revision, or the accommodation of exception requests based on these understudied variables). Several variables identified in the previous cohort were noted to have reversed sign (changed from positive to negative or negative to positive prediction of mortality) in the updated cohort. Waitlist survival variables in this category include: pulmonary fibrosis, other; diabetes; FVC <80% spline, group D; cardiac index < 2 L/min/m2; and CVP > 7, spline group B. The Committee proposes to remove 4/5 of these variables with the exception of pulmonary fibrosis, other. This hazard ratio for waitlist mortality for pulmonary fibrosis, other changed from -0.21 (p= 0.6297) to 0.21 (p=0.2093). This variable was retained in the model as the committee felt that the change in hazard ration could be consistence with their medical experience. - The removal of cardiac index <2 L/min/m2 may have adverse effects on patients in group B. In other models this parameter has been shown to correlate positively with mortality in pulmonary hypertension (particularly group 1 PAH). Was this variable analyzed separately for group B patients alone and was consideration given to retaining this variable for group B patients only. - Retention of pulmonary fibrosis other. Group D includes many different diagnosis codes and the category of pulmonary fibrosis, other is the most vague and therefore may be quite heterogeneous in composition. It is unclear how this diagnosis category is utilized by centers and effort to use more specific coding should be encouraged. The hazard ratio for this variable for mortality switched from positive to negative but without significant p-values. As there is no statistical correlation with mortality in the model, and this category is not very clearly defined we question the decision to retain it in the model. Post-transplant survival variables in this category include: pulmonary fibrosis, other; sarcoidosis, PA>30; sarcoidosis, PA <=30; and functional status, no assistance. The Committee proposes removal of pulmonary fibrosis, other; and functional status, no assistance. These variables were noted to no longer be predictive based upon high p-values. The sarcoidosis variables changed from negative to positive hazard ratios for post-transplant 1-year mortality. The sarcoidosis variables were retained as they were noted to be still predictive (p<0.0001 for sarcoidosis, PA > 30) or possibly predictive (p = 0.0736 for sarcoidosis PA <= 30) based upon low p-values and the Committee felt that the findings of the model were consistent with medical expertise. Implementation Considerations - Requested feedback: The Committee would like feedback regarding whether there is a benefit to waiting to implement changes concurrently with continuous distribution. - There does not appear to be a clinical justification for delay in implementation of changes to the model. Therefore, the decision of whether to implement changes now or concurrently with continuous distribution may largely be based upon the ability to analyze the impact of these changes in the future. Potential impact on select patient populations: - As noted above, the removal of cardiac index <2 could adversely affect group B candidates. However, this does not appear to be apparent in figure 2. - While the LAS model appears to identify and prioritize the highest risk patients it is less sensitive in its ability to stratify and identify risk amongst certain groups of patients, particularly those with COPD and cystic fibrosis resulting in large cohorts of patients with minimal difference in LAS values. Future incorporation of other disease specific variables into the model could help to more accurately reflect prognosis for such patient groups. Additional feedback requested: Are the appropriate variables being removed from the calculation? - See comments above re.: cardiac index < 2 and pulmonary fibrosis, other. Should the committee add any transition procedures to protect any specific population - No recommendations re. transition procedures. The Committee may wish to remind transplant centers of the potential to request a LAS adjustment when they are concerned that the patient’s transplant urgency is not reflected in their LAS>. - The pediatric practitioners did not feel that there was a need for transition procedures to protect our populations. We would expect, however, given the drop in LAS rank for diagnosis group A candidates, that there will be ongoing analysis to ensure that there is not a significant increase in waitlist mortality following implementation of the current proposal.
Region 8 | 09/22/2020
Region 8 vote: 4 strongly support, 9 support, 6 neutral/abstain, 0 oppose, 0 strongly oppose
Region 3 | 09/15/2020
Region 3 vote: 0 Strongly Support, 15 Support, 10 Neutral/Abstain, 0 Oppose, 0 Strongly Oppose This proposal was on the non-discussion agenda for the regional meeting.
Region 7 | 09/10/2020
Region 7 vote: 7 Strongly Support, 4 Support, 3 Neutral/Abstain, 0 Oppose, 0 Strongly Oppose No Comments
Anonymous | 09/01/2020
Being a candidate for a lung transplant I agree that allocation scores should be revised That however is not the only issue. People that have great insurance have an edge by being double listed. In todays society we have the ability to transfer donors lungs anywhere in the United states yet we have regions which are unfairly limited. Many candidates in region 5 have short wait times and have lower LAS allocation scores yet they are given lungs ahead of those that are in grater need. I myself have waited almost 4 years. Those who get on the list in region 6 go to region 5 and wait on occasion less than 30 days and these are candidates that have the same diagnosis and lowers LAS acores. That is what should be addressed.
Region 5 | 08/28/2020
Region 5 vote: 4 Strongly Support; 19 Support; 8 Neutral/Abstain; 0 Oppose; 0 Strongly Oppose. No comments
Region 4 | 08/26/2020
Region 4 vote: 4 Strongly Support, 10 Support, 9 Neutral/Abstain, 0 Oppose, 0 Strongly Oppose This proposal was on the non-discussion agenda for the regional meeting.
Andrew Rivard | 08/24/2020
The outcome of the Lung Allocation Score is a composite number of acuity factors leading to a ranking of recipients. The score result should ideally tie to something that is testable as a hypothesis and comparable to prior publications, for example, 1 yr and 5 yr post transplant survival. The outcome of the composite number thus should ideally be able to produce an estimated 1yr and 5 yr survival rate (+/- SD). Therefore the patient with the highest composite score can be compared not only on their estimated survival; but their actual survival following transplantation. Thus the new cohort of transplant patients using the continuous distribution model can assist revision of the new scoring model by comparing estimated to actual survival. Furthermore, the new paradigm can be quickly compared with the prior transplant patient survival using the DSA model without having to wait a year.