New organ allocation criteria associated with decreased deaths on liver transplant waiting list

Changing the method by which donated livers are allocated to potential transplant patients appears to have decreased the number of deaths among individuals on the waiting list as well as shortened the time to transplantation, according to a report in the November issue of Archives of Surgery.

Since 1991, the number of liver transplantation candidates on the waiting list for donor organs has increased by a factor of ten, while the number of donor livers has only doubled, according to background information in the article. In 1998, four categories of medical urgency were established to prioritize patients with end-stage liver disease on the waiting list; as the list lengthened, duration on the list became the major way to sort patients within each category. On Feb. 27, 2002, the Model for End-stage Liver Disease (MELD) score—an objective score based on several laboratory values—was adopted in an attempt to allocate donor organs more equitably and based on medical urgency.

Mary T. Austin, M.D., M.P.H., and colleagues at the Vanderbilt University Medical Center, Nashville, Tenn., studied the outcomes associated with this change in policy by studying patients on the waiting list from March 1, 1999, to July 30, 2004—36 months before and 29 months after adoption of the MELD scoring system. Information about 60,392 individuals age 18 or older on the waiting list at any point during this period was obtained from the United Network for Organ Sharing data file.

The change in policy was associated with an immediate increase in number of deaths among individuals on the waiting list, from about 11 deaths to 13 deaths per 1,000 registrants per month. However, this was followed by a decline over time of about .09 deaths per 1,000 individuals per month.

“An immediate effect of decreased waiting time was also noted (from approximately 294 to 250 days; -44.4 days), which reached a new, lower post-intervention steady state,” the authors write. “With the transition in allocation policy from a system that emphasized waiting time to one that favored disease severity with a de-emphasis on patient waiting time, many less-ill registrants placed on the list for the sole purpose of ‘banking time' may have been removed, leading to an overall decrease in the time to transplantation for the remaining registrants.”

The change did not appear to affect the number of new registrants per month or the survival rates three or six months after transplantation. “Given that the new allocation policy prioritizes patients with higher MELD scores to receive transplants, these results are encouraging,” the authors write.

“In solid-organ transplantation, the liver transplantation community was the first to adopt an objective score as the basis of organ allocation policy,” they continue. “Careful evaluation of this major change in the allocation of deceased donor livers is essential because it may direct future allocation policies. Using the interrupted time series method, our data provide more conclusive evidence that this policy had a positive impact on waiting list mortality. Because significant resources are expended in efforts to equitably allocate organs, this work provides empiric justification of this policy change.”

http://archsurg.ama-assn.org/