A mistake in the recently implemented lung transplant algorithm caused harm to seriously ill and dying patients

The new algorithm was designed to equitably distribute lungs to individuals in critical need of life-saving transplants. However, a flaw in the process for allocating organs to seriously ill patients resulted in some individuals not receiving the necessary care they were entitled to, as reported by the Tribune.

Specifically, patients with type O blood received fewer transplants last year than expected, according to records obtained by the Tribune and discussions with patients, surgeons, and advocates. This discrepancy arose because the new system did not fully consider that type O patients can only accept lungs from donors who also have type O blood.

The issue occurred over a six-month period in 2023 but is only now being publicly disclosed amid controversy over the extent of the impact and whether the organization overseeing transplants should have been more transparent about the error.

A group of transplant surgeons has criticized the Organ Procurement and Transplantation Network, responsible for setting organ distribution rules under a federal contract, for not providing sufficient public information about what they described in a letter as a “deeply troubling” incident.

When the network revised its algorithm for lung distribution in March 2023, it promoted the updated system as more efficient and fair, aimed at preventing vital organs from going unused. The changes included eliminating strict geographic boundaries on how far organs could be transported for transplantation, recognizing that these limitations sometimes caused patients to wait excessively long for suitable organs in their local area. Additionally, the new algorithm introduced a scoring mechanism that weighed multiple factors related to a patient’s transplant urgency and compatibility with the donor organ.

In July, the Organ Procurement and Transplantation Network acknowledged an error in its revised algorithm and released a report indicating that approximately 35 fewer lung transplants had been provided to patients with type O blood during the initial three months of the program’s implementation than would have been expected. A corrective change to address the issue was implemented at the end of September. However, a subsequent six-month report issued by the network did not revise the estimated impact beyond the initial 35 transplants.

Presenting their findings at the American Transplant Congress this month, a team from the University of Colorado argued for a higher estimate, suggesting that the error likely led to 138 fewer lung transplants for type O patients. Type O blood is the most common type, comprising nearly half of the U.S. population.

“This situation simply should not have occurred,” remarked Jesse Schold, a surgery professor at Colorado and coauthor of the paper, in an interview with the Tribune.

During the presentation, Schold and his colleagues expressed concerns that even after the correction, the system might still result in disparities in transplant rates based on blood type.

The Organ Procurement and Transplantation Network declined interviews with officials but provided a written statement from network President Dianne LaPointe Rudow. She clarified that while some patients with blood type O did receive transplants, they obtained lungs from donors with compatible blood types.

When asked about the number of patients affected by the error, the network responded that it was challenging to accurately predict outcomes due to various dynamic factors involved in organ allocation, including organ characteristics, transplant center preferences, and constantly updated waiting lists.

Explaining the algorithm’s error, network officials attributed it to a fundamental scientific mistake in the modeling process, which incorrectly assumed that recipients could receive lungs from donors of any blood type.

“While no patients received organs of incompatible blood types in reality, as multiple safeguards prevent such mismatches, type O patients were effectively deprioritized under the new system, resulting in fewer lung transplants for them,” the network acknowledged.

The revisions made to transplant algorithms, which were developed over several years, highlight the complex challenges faced by the Organ Procurement and Transplantation Network (OPTN) in managing the allocation of critical organs.

Determining the recipients of available donor organs involves a formula that considers factors such as medical urgency, likelihood of survival, biological factors like blood type or physical characteristics, patient access to transplant centers, and logistical efficiency including transportation distances.

In recent times, OPTN has struggled with the role of geographical proximity in patient care and has moved away from rigid distance-based rules. Previously, patients with lower medical urgency but closer proximity to donor hospitals could sometimes be prioritized over more critically ill patients, a practice OPTN aimed to reform.

“Geography poses inherent challenges in formulating equitable transplant policies nationwide,” remarked Yolanda Becker, former president of the OPTN/UNOS board of directors. “There are disparities in the distribution of transplant centers, organizational differences among organ procurement entities, and regional variations in disease patterns leading to organ failure and causes of death that enable organ donation.”

The model introduced last year, known as “continuous distribution,” is intended for eventual use across all organ types by OPTN.

Shortly after implementing the revised algorithm for lung transplants, however, OPTN realized it disadvantaged patients with type O blood. Type O patients require organs from type O donors due to biological compatibility, but organs from type O donors can also be successfully transplanted into recipients with other blood types.

To ensure fair distribution of lungs from type O donors, the algorithm needed adjustments to accommodate the unique needs of type O patients. The detection of this issue occurred through routine monitoring by OPTN, prompting a proposed solution detailed on a dedicated webpage last August, with final approval of changes made in September.

By October, a six-month monitoring report was completed by OPTN, showing an overall increase of 11.2% in lung transplants and fewer candidates dying on the waitlist among other improvements.

However, the report acknowledged a decrease in lung transplants for type O recipients (from 646 to 601) while noting an increase for recipients of other blood types.

Criticism from the American Society of Transplant Surgeons followed, with its leadership questioning the transparency and depth of OPTN’s report, particularly regarding the modeling and data entry error that impacted type O patients.

OPTN defended its handling of the issue, stating that root-cause analyses are treated confidentially to encourage thoroughness and openness among participants, akin to peer review processes.

The surgeons’ group requested a supplementary report disclosing the number of affected patients and measures taken to prevent similar blood-type issues in the future. In response, OPTN reiterated its commitment to early issue detection and data stabilization under new systems, acknowledging the need for time to gather sufficient post-implementation data.

Seth Karp, a former board member of the Organ Procurement Transplantation Network and director of the Vanderbilt Transplant Center, criticized the network’s handling of the situation, emphasizing the need for complete transparency regarding the algorithm error, its timeline, detection, and corrective actions. He advocated for assembling a panel of experts to ensure such mistakes are prevented in the future.

The algorithm issue did not escape notice from patients affected by the changes. On the webpage discussing the proposed solution, several commenters highlighted the adverse impact on patients with type O blood.

One anonymous commenter, waiting for a lung transplant for five months, expressed frustration: “I am O-blood type and have been on the ‘Wait’ list for five months. I have not even had a dry run! To say I don’t feel like I’m in the game is an understatement. I have always felt being an O-patient has been a disadvantage. I commend OPTN for identifying the disparity with O patients and I support corrective life saving changes to the CAS point system.”

David Sperlein, 62, who needed a lung transplant due to ongoing health issues exacerbated by COVID-19, shared his experience of waiting anxiously for a transplant. Despite being informed by doctors that he had a competitive score under the system, Sperlein, who has type O blood, did not receive a donor lung until January 2024, after a prolonged wait that took an emotional toll.

Jeannine, his wife, monitored the organ network’s website regularly and praised their medical team for keeping them informed about changes to lung allocation rules. She expressed relief when policies were adjusted in October, offering renewed hope for O patients like David.

Dr. Robert M. Reed, medical director of the University of Maryland lung transplant program, characterized the algorithmic error as a “perplexing mistake” that disproportionately affected O patients. He noted a significant drop in O transplants during the erroneous period, highlighting the critical impact of timing on patient outcomes.

Since corrective measures were implemented, the center has observed an increase in O transplants. However, Reed cautioned that prolonged waits could lead to further deterioration in patients’ health and quality of life.

“Many patients on the waitlist, like Mr. Sperlein, are at risk for decline,” Reed remarked. “While he was fortunate to receive a good lung and is doing well, such outcomes are not common.”

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