Dr. Brian Donahue received the $756,000 NIH grant to study the coagulation system. (photo by Anne Rayner Pollo)
Organ waiting list procedures change
The United Network for Organ Sharing (UNOS) has developed a new system to prioritize patients waiting for liver transplants. Effective Feb. 27, the system is based on statistical formulas determined by a combination of medical factors.
Dr. C. Wright Pinson, H. William Scott Jr. Professor of Surgery, said the new system, called MELD (Model for End Stage Liver Disease), provides a more objective assessment for determining the severity of patient needs.
“This MELD policy is potentially an incremental improvement in organ allocation because it uses all objective criteria and no subjective criteria like the former scoring model,” said Pinson, surgical director of the Vanderbilt Transplant Center and chairman, Department of Surgery. “Also, it allows finer stratification from approximately four to 30 categories of severity. No patients now waiting will be disadvantaged by the implementation of these new methods.”
Organ allocation is an issue that Pinson and the Vanderbilt Transplant Center have been involved in for the past decade.
“There has been a lot of debate on how to most effectively allocate organs,” he said. “Vanderbilt has significantly influenced the debate.”
Pinson, who sits on the UNOS board of directors, said approval of the changes should equate to better outcomes.
Research has shown that the MELD formula accurately predicts most liver patients’ short-term risk of death without transplant.
When a similar program to the MELD system was tested in the New England area over a nearly three-year period, the patient outcomes were much improved, Pinson said.
Under the current system, patients are grouped into four medical urgency categories using a scoring system based on lab test results, symptoms of liver disease and waiting time.
A major concern with the present system is the subjective interpretations made by physicians on the severity of a patient’s symptoms. Another source of debate focused on the issue of waiting time. Many physicians said waiting time is a poor indicator of how sick a patient is or how urgently a patient needs a liver.
“The greatest difference of opinions on how organs should be allocated existed in the area of liver transplantation,” said Pinson. “The intense concern surrounding this lifesaving procedure focused the effort on securing improved allocation methods here first.”
Dr. J. Harold Helderman, medical director of the Vanderbilt Transplant Center and professor of Medicine, Microbiology and Immunology, is a member of the Advisory Committee on Organ Transplantation. He said the transplant community has struggled with how best to allocate such a scarce resource in a manner that combined with organ efficacy and fairness.
“In addressing the balance, the community has continued over the many years to look at objective data and continue to tinker with and improve the system,” Helderman said. “The new system is not a revolution, but an evolution.”
Using the current scoring method made it difficult to accurately identify which patients had more severe liver disease and were in greater need of a transplant.
MELD will better determine the severity of a patient’s illness and reduce the influence of waiting time in the selection of patients. Waiting time will only be used to break ties among patients with the same score and blood type.
Under the new system, patients will receive a score ranging from 6 (less ill) to 40 (gravely ill). The scores are based on how urgently a patient needs a transplant within the next three months. It is determined by a formula using three medical tests:
• bilirubin, which measures how effectively the liver excretes bile.
• INR, which measures the liver’s ability to make blood clotting factors.
• creatinine, which measures kidney function.
MELD will replace the previous Status 2A, 2B and 3 categories. Status 1, patients with acute liver failure and a life expectancy of less than seven days without a transplant, will remain in place as the highest priority for receiving an organ.
Scores will be assessed throughout a patient’s wait to ensure that donated livers go to the patients in greatest need.
A similar system will be implemented for pediatric patients called PELD (Pediatric End Stage Liver Disease Model). This model’s score combines bilirubin, albumin, INR, creatinine, growth failure and whether the child is less than 1-year-old.