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The International Society for Heart and Lung Transplantation (ISHLT) solicited feedback on the Organ Procurement and Transplantation Network (OPTN) Special Public Comment on the proposal to modify lung allocation by blood type. Feedback was solicited from the ISHLT Advocacy Committee and the ISHLT Lung Failure Interdisciplinary Network Steering Committee. In general, both groups were in favor of making changes to the Composite Allocation Score (CAS), with the goal of combating inequities in organ allocation by blood type. The ISHLT commends the OPTN for taking a proactive approach to revising the CAS in real-time. Further, we recognize that this effort has taken place much faster than prior revisions to lung allocation in the United States. It is our hope that the CAS will continue to be revised in realtime, to ensure equity in organ allocation for all patients, regardless of blood type, racial/ethnic background, diagnosis, or other demographics.

Since the CAS went live in March 2023, there was a decrease in transplants for patients with blood type O, which was not predicted by the prior modeling. Both the ISHLT Advocacy Committee and Lung Failure Interdisciplinary Network Sterring Committee were glad to hear that the OPTN Lung Committee was presented with several potential fixes to the inequities that arose for patients with blood type O. We recognize that the OPTN Lung Committee selected the model they felt would best reduce inequities faced by patients with blood type O, and agree with the implementation of a revision to the CAS in short order.

Although the ISHLT generally supports revising the CAS, there were some questions that arose in our discussions. Since the proposal awards a full 5 points for O recipients, there was concern that this change will nearly eliminate the ability for centers to use blood type O organs for non-blood type O recipients. In particular, for blood type AB candidates, who have the largest increase in distance traveled of all blood types. If this revision is enacted, nearly all patients with blood type O will have a CAS subscore above 23 points. As such, patients with other blood types will need to achieve a medical

urgency between the 95th to 99th percentile in order to equal the extra 5 points allocated for blood type O recipients. Ultimately, allocating a full 5 points may swing the pendulum too far towards blood type O candidates, and may effectively eliminate the use of blood compatible donors. Another point brought out by the committee was the increased points allocated to blood type B candidates. The public comment did not explicitly describe rationale for this, so providing information for this change would be helpful.

Given the issues expressed about the number of awarded points, the ISHLT also recommends that the OPTN show updated modeling of the transplant rate metric under the proposed changes. Additionally, since the MIT model uses an older version of Thoracic Simulated Allocation Model, it would be useful if the proposal provided some information about how the use of the older Thoracic Simulated Allocation Model might have influence these results.

Finally, the ISHLT would like to highlight some process concerns. The Lung Committee and the OPTN have created a new type of public comment (“special public comment”) that isn’t spelled out in the OPTN bylaws, and has a shorter timeframe for comment submission (14 days) than either the emergency action (where the action precedes comment) or “expedited actions” (predefined updates in stipulated in policy that are automatically approved without Board approval as long as no significant objections are raised). Both of the latter have minimum public comment periods of 30 days. ISHLT strongly encourages the OPTN to consider a minimum of 30 days for any prospective public comment period to allow for non-profit professional organizations to gather feedback and convene their Board or Executive Committee to approve an organizational response.

Finally, although the notification mentions an “expedited implementation” neither the proposal nor the policy notice make clear that the OPTN intends to have the Executive Committee or Board vote on this shortly after the public comment period closes. The ISHLT hopes that the OPTN can clarify their intentions so that the community can understand and accept the precedent that is being set here for rapid modification of an existing policy, with a significantly shorter public comment period than is stipulated for other public comment pathways.