November 30, 2007

Liver allocation system lowers death rates: study

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Wright Pinson, M.D.

Liver allocation system lowers death rates: study

Vanderbilt University Medical Center researchers have found that the United Network for Organ Sharing's (UNOS) adoption of an objective-only method of allocating donated livers has lowered the number of deaths among patients on the waiting list.

In 2002, UNOS adopted the Model for End-state Liver Disease score (MELD) system, which uses laboratory-based values to characterize a patient's need for liver transplantation.

Previously, patients who spent the longest time on the waiting list for a liver were often given priority. After the change, wait times became less of an issue while severity of condition was prioritized.

The change was the subject of great debate and prompted researchers at VUMC to examine the outcomes associated with the new liver allocation policy. Results of the study were released last week in the Archives of Surgery.

“Using the MELD score allowed transplant centers to base need on completely objective criteria,” said Wright Pinson, M.D., senior author of the study and director of the Vanderbilt Transplant Center. “This method was viewed as more equitable and driven by medical urgency. How long a patient was waiting did not play into the formula.

“Our report was one of the earliest and best performed studies using a rigorous statistical method to examine the data,” said Pinson, also associate vice chancellor for Clinical Affairs at VUMC. “The credit goes to Mary Austin, who was a quality scholar in the M.P.H. program at Vanderbilt at the time. She put her research training skills to work and it served great advantage to the transplant community.”

The Vanderbilt study used UNOS data from three years prior to the policy change through two years after the acceptance of the MELD score system, which included more than 60,000 patients.

“The way we allocate organs has always been up for debate,” said Austin, M.D., M.P.H., now of Children's Hospital Los Angeles. “What this study says is that adopting the MELD score system reassured the transplant world that we are doing the right thing in providing a more equitable distribution of organs, which are a precious resource.

“Prior to MELD, sometimes people at some centers were placed on the list before they were even sick enough to really need it. Our goal is to transplant sick people and prevent them from dying.”

The study, which also served as Austin's thesis, did show that after an initial increase in the number of deaths of those on the waiting list, an overall decrease was associated with the MELD policy change as well as a decline in time to transplantation.

Authors also state that the adaptation of the MELD scoring system had no significant impact on post-transplant survival and that continued outcomes work on the allocation policy is warranted.