Split liver transplants for young children proven to be as safe as whole organ transplantation

(Press-News.org) Boston, Mass.— A new study shows that when a liver from a deceased adult or adolescent donor is split into two separate portions for transplantation—with the smaller portion going to a young child and the larger to an adult—the smaller portion used for the child will last just as long as if the child had received a whole organ from a donor close to his size.

The data, collected and analyzed by a team led by Boston Children's Hospital researchers Heung Bae Kim, MD, and Ryan Cauley, MD, MPH, was published online in Liver Transplantation, a journal of the American Association for the Study of Liver Diseases and the International Liver Transplantation Society. Data on graft survival and mortality for adult recipients of split livers is currently being compiled for a separate study to be released soon.

Examining pediatric data provided by the United Network of Organ Sharing (UNOS), the authors researched the mortality and graft survival of 2,679 patients under the age of two who received liver transplants between 1995-2010. Of these cases 1,114 involved partial livers and 1,565 involved whole organs. Their research indicates that from 1995- 2000 partial grafts had a higher risk of failure, but from 2000-2006 that risk was lower, indicating partial liver transplants became safer as experience with this practice increased. By 2006 both split and whole organs had similarly low rates of both graft failure and mortality, suggesting that their use could be increased to meet the demand for smaller grafts.

"Infants and young children have the highest risk of death on the liver transplant waiting list, mainly due to the shortage of appropriately sized organs," says Kim, senior author on the study and director of Boston Children's Pediatric Transplant Center. "But based on this new data, split liver transplantation may prove to be the answer to this difficult problem. If more liver donors were made available for consideration as split liver donors it could significantly reduce the number of young children on the waitlist for a liver, potentially reducing the waitlist mortality rate for this highly vulnerable population to near-zero."

Due to their small body size, infants and young children in need of a liver transplant cannot accommodate a whole graft (donated liver) from a larger sized donor. As a result these patients have three treatment options:

wait for a whole liver from a similarly sized deceased donor to become available receive a portion of liver from a living donor (usually a family member) receive a split liver transplant from an adolescent or adult deceased donor

In split liver transplantation, a liver from a deceased donor is surgically separated into two unequal size organs—the smaller portion is used to transplant the child while the larger portion is used to transplant a large child or adult patient.

The process of splitting a liver for transplant and allocating the halves to two different recipients began in the mid 1990s and has become more widespread over time. However, adoption of this technique has met some resistance due to early data suggesting that split liver transplants have a higher risk of graft failure and death than whole liver transplants. This new research reveals that this is no longer true among pediatric recipients.

"Our study confirms that there is no longer any increased risk of graft failure and mortality in the very young, regardless of whether or not the patient receives a partial or whole graft," says Cauley, first author on the paper. "We are hopeful that this new data will support ongoing efforts to make modifications in the national liver allocation policy that makes more livers available for splitting, thereby saving lives and improving quality of life for many children and their families."

### Boston Children's Hospital is home to the world's largest research enterprise based at a pediatric medical center, where its discoveries have benefited both children and adults since 1869. More than 1,100 scientists, including seven members of the National Academy of Sciences, 13 members of the Institute of Medicine and 14 members of the Howard Hughes Medical Institute comprise Boston Children's research community. Founded as a 20-bed hospital for children, Boston Children's today is a 395 bed comprehensive center for pediatric and adolescent health care grounded in the values of excellence in patient care and sensitivity to the complex needs and diversity of children and families. Boston Children's is also the primary pediatric teaching affiliate of Harvard Medical School. For more information about research and clinical innovation at Boston Children's, visit: http://vectorblog.org.