Allocation Out of Sequence (AOOS)

Improving Allocation Practices to Strengthen Public Trust and Patient Outcomes

The Organ Procurement and Transplantation Network (OPTN) creates, implements, and monitors national policies that describe how donated organs should be allocated to patients waitlisted for a transplant. Laws, regulations, and policies require that organs are allocated fairly, transparently, and according to the criteria the OPTN establishes. Allocation Out of Sequence (AOOS) occurs when OPTN members allocate organs outside of the OPTN-designed match run; generally, these AOOS actions do not comply with OPTN allocation policies, resulting in patients losing their opportunity to receive an organ to which they were matched. As the OPTN modernizes, HRSA and the OPTN are committed to addressing AOOS to protect public trust, ensure the policies that the OPTN designs and enacts are followed, and uphold patient safety.

What is AOOS?

The OPTN, as directed by HRSA, developed shared operational and analytic definitions describing organs allocated out of sequence.

Operational definition expandable content

AOOS is when an organ is offered or accepted or transplanted into a transplant candidate or potential transplant recipient (PTR) that deviates from the match sequence and is not consistent with OPTN policy.

Analytical definition expandable content

AOOS is identified through the use of one or more of the following organ offer bypass codes:

• 861: Operational - Organ Procurement Organization (OPO)
• 862: Donor medical urgency
• 863: Offer not made due to expedited placement attempt
• 887: Not Offered - expedited placement
• 799: Other (specify)

Example of AOOS

What about “wasting” a donated organ?

The OPTN Final Rule provides a policy-compliant way to ensure that, in emergencies or unintended disruptions, an organ allocated to a patient at a transplant center may be emergently used in another suitable patient. While some stakeholders have expressed a hope that non-compliance with the OPTN allocation policies prevents wasting donated organs, in practice, organ non-use has gone up as AOOS has also risen.

The OPTN was advised by HHS that the “wastage provision at 42 CFR 121.7(f) [does not] authorize out-of-sequence offers by OPOs. This provision on its face provides authority to transplant centers to determine that organ recipients should be identified other than in accordance with 121.7 and OPTN policies and procedures and does not provide this authority to OPOs. And insofar as transplant programs rely on this provision to justify out-of-sequence placements of organs, we believe they may only do so to the extent that the organs would otherwise go to waste.”

Organ allocation, under requirements of the Final Rule and OPTN Bylaws and Policies, is required to be fair, offer organs not to transplant centers but instead to potential recipients, be ranked by priority, and be sequentially offered to potential recipients.

See more about how donated organs are matched to potential recipients here.

Why does AOOS raise concerns?

AOOS poses serious risks and consequences:

• It may violate federal laws and policies, including the National Organ Transplant Act (NOTA), the Final Rule, and OPTN policies and bylaws.
• It can lead to patients being unfairly bypassed, denying them potentially life-saving transplants.
• It can damage public trust in the integrity, transparency, and fairness of the organ procurement and transplant system.

Accountability to patients is fundamental to meaningful OPTN modernization. Adherence to established policies is not optional. In fact, it is the foundation of accountability. Ensuring this accountability protects patients, supports health providers, and preserves the credibility of the national procurement and transplant system.

What can we learn from data?

While analyses of AOOS will continue and evolve moving forward, early findings reveal several important trends:

• AOOS is occurring across multiple organ types and regions, suggesting it is not limited to a specific area or organ system.
• Candidates who meet established priority criteria may still be bypassed, raising concerns about fairness in the allocation process.
• Limited transparency around AOOS is causing uncertainty and concern among both patients and healthcare providers.

These initial insights highlight the urgent need for greater data transparency and policy clarity.

A public dashboard is in development to track AOOS trends and display the frequency of AOOS events, offering a clearer picture of the allocation system’s performance.

What actions are being taken to address AOOS?

The OPTN is working to ensure that organ allocation is fair, transparent, and in line with national policy by:

• Ensuring all organ allocation follows laws, regulations, and OPTN policies
• Limiting AOOS to rare, well-justified, and transparent exceptions
• Strengthening fairness and rebuilding public trust in the procurement and transplant system
• Collaborating with stakeholders across the OPTN community to ensure that different perspectives, especially those of patients and their families, are represented

Progress is already underway:

• HRSA is reviewing OPTN’s draft AOOS Remediation Plan to strengthen national allocation policy and clarify definitions.
• The OPTN published standardized definitions of AOOS to guide future data analysis, policy development, and oversight. Input from the Data Advisory Committee (DAC) and the Patient Affairs Committee (PAC) was essential in shaping the AOOS definitions, ensuring transparency and meaningful engagement across the transplant community.

Coming soon:

• A public dashboard is in development to track AOOS trends and display the frequency of AOOS events—offering a clearer picture of the allocation system’s performance.
• New compliance criteria will be introduced to audit the use of "Other, specify" organ offer refusal and bypass codes (e.g., 799). Bypass codes document why a patient was skipped instead of receiving an offer. Each use of an “Other, specify” code will require documented justification, helping to reduce misclassification and improve policy adherence. Updated policies will reinforce accountability and ensure appropriate use of bypass reasons.

This website will be updated regularly with progress, data trends, and other relevant information.

Stay up to date

• Monthly updates: HRSA OPTN Modernization initiative
• Policy Comments: Public Comment Page
• AOOS Critical Comments & Responses: Critical Comments Archive

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