As work continues to address allocation out of OPTN sequence (AOOS), additional resource information is now available below. This includes answers to frequently asked questions and recommendations for how you can learn more and participate in AOOS remediation efforts.
The main AOOS resource page on the OPTN website will continue to be updated with news and information as it becomes available.
On this page:
- How does AOOS undermine fairness?
- Why is it important to address widespread AOOS?
- What has changed as a result of the recent notice about AOOS to the OPTN community?
- Why is this issue in focus right now?
- What does it mean to follow the match run?
- What are the roles of HRSA and the OPTN in addressing AOOS?
- Is it ever okay to allocate an organ out of sequence?
- What will happen if my team allocates an organ out of sequence?
- Don’t we need AOOS to prevent organ non-use?
- What if organ non-use goes up as a result of increased allocation policy compliance?
- Is the OPTN holding transplant centers accountable for AOOS?
- What can I do to get involved in AOOS remediation efforts?
FAQs
Fairness, or equal access to organs, is a central principle of the OPTN. Fairness in organ allocation is implemented through the match run sequence, which is defined by allocation policies created, implemented, and enforced by the OPTN (PDF - 3 MB). Allocation of organs outside of those OPTN-defined policies not only undermines patient safety, but is also in conflict with the fairness that those policies were designed to enact because the patients who are bypassed are denied access to potentially life-saving transplants.
AOOS undermines fairness and patient safety. (See the question, How does AOOS undermine fairness?) AOOS can also be seen to undermine the OPTN itself. The OPTN was created by the National Organ Transplant Act (NOTA) in 1984. According to NOTA and its implementing regulations, creating policies and a matching system for the allocation of organs, which are a national resource, is a central purpose of the OPTN. Because the establishment of allocation policies is a key reason why the OPTN exists, routine non-compliance can be seen as a serious threat to the role and responsibilities of the OPTN and a violation of the law.
Nothing has changed about OPTN policies, HHS regulations, or OPTN members’ obligation to follow them. The notice was intended to serve as a reminder and clarification of the existing rules, requirements, and obligations of the OPTN, which apply to all OPTN members.
The OPTN Obligations described at F.1.e.1 in the Membership and Management Policies (PDF - 2 MB) state that:
By accepting membership in the OPTN, each member agrees to comply with all OPTN Obligations, which include all of the following:
- Applicable provisions of the:
- National Organ Transplant Act, as amended, 42 U.S.C. 273 et seq.
- OPTN Final Rule, 42 CFR Part 121
- OPTN Bylaws
- OPTN Policies
- Acting to avoid risks to patient health or public safety
- Fulfilling all requests for information
For most of the OPTN’s history, AOOS was an exception used in rare instances where the allocation policies defined and implemented by the OPTN were insufficient to place a donated organ with a recipient. As recently as 2018, only about 1 in 45 of all transplanted organs was AOOS. The rate of AOOS started increasing in 2019, accelerating to the point where about 1 out of every 5 organs was AOOS in 2024.
Increasing rates of AOOS have been observed and discussed extensively within the transplant and scientific communities. Some examples of recent published studies include:
- August 2025: Underrecognition of deceased donor kidney out-of-sequence allocation due to increasing use of free-text coding
- August 2025: Association between out-of-sequence allocation and deceased donor kidney nonuse across organ procurement organizations
- February 2025: Contemporary prevalence and practice patterns of out-of-sequence kidney allocation
- May 2022: Deceased donor kidneys allocated out of sequence by organ procurement organizations
There is no overwhelming consensus on what has driven this change in practice. Common theories point to systematic shifts that have added complexity to organ allocation, including longer waitlists and increasing medical complexity of donor and recipient patients. Still, AOOS has consistently increased since 2019, over an era that includes observable shifts following significant changes to allocation policies (including acuity circles and continuous distribution).
Increasingly, organ allocation that fails to meet OPTN policy requirements is being treated as a standard practice instead of a rare exception. This undermines patient safety, a core commitment of the OPTN, and led to HRSA receiving a critical comment (PDF - 92 KB) from an OPTN community member, which launched an ongoing AOOS remediation process with the OPTN. Even as rates of AOOS have started trending down since this remediation process began in early 2025, the practice remains unacceptably common and highlights the need for refinements in allocation policy.
To learn more about AOOS, see the OPTN’s AOOS webpage.
The OPTN creates and implements policies (PDF - 3 MB) defining the order in which organs are to be offered to potential transplant recipients. Following the match run means adhering to those existing OPTN policies. The allocation algorithms for each organ are set by the OPTN and described in OPTN Policies 6-12. Rules for how that algorithm is enacted through offers and acceptances are outlined in OPTN Policies 5.4.B and 5.6.B.
Practice, policy, and technical implementation of policy all evolve over time to better meet the needs of patients, families, and OPTN members. The OPTN changes policy to meet emerging circumstances and reflect best practices, and ensures that OPTN IT systems are updated to support policy implementation. HRSA monitors the system and supports the OPTN in instances where its policy, operations, technology, and/or member practice are misaligned.
Policy compliant allocation is preferable to noncompliant allocation when possible, but AOOS is preferable to the non-use of an organ that is suitable for transplant.
Under appropriate alignment of policy, practice, and technology, AOOS should be a rare occurrence, typically a consequence of unusual circumstances. It should only occur in cases where the allocation teams have first done everything possible to allocate that organ in compliance with OPTN allocation policies.
The OPTN Membership and Professional Standards Committee (MPSC) will monitor allocation patterns and trends and will identify failures to allocate organs according to OPTN policies. These assessments may consider historical trends as well as recent behavior. HRSA is leading the expanded collection of organ procurement process data, which will support data-driven assessments of the necessity of and contributing factors to AOOS events overall and for specific cases.
The OPTN designed existing allocation policies to optimize both the use of donated organs and fairness in which patients receive organ offers. While organ utilization is often used as a justification for AOOS, the data so far do not support this claim.
There is a growing body of evidence around this question, including:
- An article in Health Affairs in May 2025 showed a decline in AOOS across OPTN members in recent months without any corresponding increase in organ non-use.
- An article in the American Journal of Transplantation in February 2025 found that between 2021 and 2023, “[e]ven with substantial increases in OOS allocation, the impact on nonuse rates is minimal.”
- One OPO transitioned to a different organ allocation protocol in March 2025. Over the following months, they saw decreasing rates of both AOOS and organ non-use.
As AOOS remediation activities continue, HRSA and the OPTN will continue to monitor organ non-use closely and will respond quickly should any negative trend emerge.
HRSA and the OPTN understand the seriousness of organ non-use and the level of concern in the community about maximizing organ utilization. We are monitoring both AOOS and non-use side by side and will continue to do so as remediation efforts continue.
Organ allocation policies and practices are dynamic and evolving, and the OPTN will work to update policies that are no longer serving OPTN members and patients. See the FAQ, “What can I do to get involved in AOOS remediation efforts?” if you would like to take action.
Yes, all OPTN members are accountable for following the policies created and implemented by the OPTN. The community letter describing AOOS and allocation policies was sent to all OPTN members, including transplant centers.
- Report instances when you or your patients were harmed by AOOS to OPTNComplaints@hrsa.gov, which is monitored by HRSA.
- Connect with the AOOS Workgroup by reaching out to OPTNBoardSupport@air.org.
- Join an OPTN committee, or reach out to committees about the ways OPTN-defined and implemented policies are and are not serving your team and your patients.
No. As long as offers are made to potential transplant recipients in the order specified by the OPTN policy-defined match run, organ allocation is considered in sequence. There is no prohibition in OPTN policy against using organ preservation technologies.
HRSA is committed to developing transparent, effective organ allocation policy that prioritizes accountability to patients. HRSA directed the OPTN (PDF - 152 KB) to pause policy development related to expedited organ allocation for three reasons:
- The OPTN has limited financial resources and multiple critical and time sensitive priorities. A number of these, including AOOS, normothermic regional perfusion (NRP), and organ donation safety are critical to the OPTN’s ability to ensure high quality care and fairness in access to care for large numbers of patients.
- These policies were developed in an environment of increasing and widespread OPTN member non-compliance with organ allocation policies, which may have impacted the data used to inform policy development.
- A pause in the development of new allocation policies will allow the OPTN to use learnings from the AOOS remediation process to help define, review, and revise future allocation policies.
Through the OPTN’s analytic definition (PDF - 100 KB) of AOOS and forthcoming consensus datasets (PDF - 75 KB), insights into the relationship between policy changes and compliance patterns will be attainable, informing OPTN policy discussions in ways that were not previously considered.
HRSA’s response to the OPTN’s EPP (PDF - 150 KB)
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