Linda Stephenson lines up before the graduate school ceremony. She received her Ph.D. in Microbiology and Immunology.
photo by Dana Johnson
Alternative graft sources studied for pediatric liver transplant patients
Although they make up only 15 percent of the liver transplant waiting list, children younger than 5 have the highest wait-list mortality rate. This information, coupled with an ongoing organ shortage, has led a Vanderbilt physician to study alternative graft sources for pediatric liver transplant patients.
Mary T. Austin, M.D., and colleagues discovered that pediatric liver transplant patients have a better survival rate using living donor grafts than organs harvested from the deceased.
According to the study results in the May issue of Archives of Surgery, one of the Journal of the American Medicine Association journals, data on all pediatric liver transplants from the United Network for Organ Sharing (UNOS) were analyzed to determine the effect of donor type on the outcome of transplantation.
There are three types of organ donor types — deceased donor whole organ, deceased donor split organ and living donor organ. The most common is deceased donor whole organ.
“Living donor recipients do better in graft and patient survival, but the reason they do better is because they are transplanted into healthier patients — those transplanted earlier in the disease state — and are associated with decreased cold ischemic time,” Austin said. “This definitely contributes to the impact on survival.
“But another important consideration is the risk to the living donor. Even though there is less than 1 percent chance of dying, there is a finite risk to an otherwise perfectly healthy individual.
“Our study contributes to the wealth of knowledge used to improve our organ allocation policies at a national level,” she said.
One of the interesting notes of the study investigation: Vanderbilt University Medical Center does not yet have a pediatric liver program. Although a national search is under way for a program leader, Austin, who is moving into pediatric surgery with a focus on pediatric transplant, was not hindered.
“Mary represents one of the young trainees here who has benefited from the Masters in Public Health scholars program,” said C. Wright Pinson, M.D., H. William Scott Professor of Surgery, associate vice chancellor for Clinical Affairs and Chief Medical Officer. “And the techniques that she has learned in this program have allowed her to analyze the UNOS national database.
“This study demonstrates what a significant effect these alternative grafts have had on pediatric transplantation. These alternative and split grafts will clearly be an important portion of the grafts that are available, perhaps 20 percent.”
Data from a 17-year period on all pediatric liver transplants with end-stage liver disease, a total of 8,771 recipients, were examined. Eighty-one percent received a deceased donor whole graft, 8 percent were deceased donor split grafts, while 11 percent were living donor grafts.
During this time frame, 3,107 transplant grafts failed, with 1,778 retransplanted and 1,329 deaths. Thirty-seven percent of the deceased donor whole organ transplants and 38 percent of deceased donor split grafts were failures, compared with 27 percent of the living donor grafts, according to study information.
“While the number of children on the waiting list has doubled since 1993, the total number of adults on the waiting list has increased sixfold in that same period,” the study reports. “The large number of adults on the waiting list affects pediatric candidates' access to organs.
“These facts stimulated the transplant community to develop living donor liver transplant and split liver transplants to increase the donor pool and help fill the gap between the availability and the demand for size-matched organs for pediatric patients.”