Increasing the number of organs for transplant
WINSTON-SALEM, N.C. – What makes a donated kidney or pancreas "acceptable" for transplant? Results from two pilot studies suggest that it may be possible to expand the current acceptance criteria for deceased donors, which could significantly increase the number of organs available for transplant each year.
"We are encouraged by our success using organs from deceased donors that would ordinarily have been discarded," said Robert Stratta, M.D., director of Transplantation Services at Wake Forest University Baptist Medical Center, in an interview. "Even organs donated after cardiac death can be suitable in some cases, which has been taboo in the past."
In 2002, the United Network for Organ Sharing (UNOS) expanded the criteria for kidney donors so that higher risk donor organs, once considered unsuitable, could now be transplanted safely. The number of kidney transplants performed at Wake Forest Baptist has doubled by using expanded criteria donors (ECDs).
In the current studies, Stratta and colleagues went a step further and looked at success rates using organs at the outer limits of acceptance criteria, which Stratta refers to as organs from "extreme" donors. The researchers found that patient and organ survival rates in transplants involving extreme donors were similar to success rates with conventional donors. Stratta reported the results last week at the American Transplant Congress 2005 meeting in Seattle, Wash., and earlier in May at the 10th Annual Congress of the International Pancreas and Islet Transplant Association in Geneva, Switzerland.
"The shortage of donated organs is a national crisis, with people on the waiting list dying every day," said Stratta. "This mandates an ongoing reappraisal of the limits of donor organ acceptability."
Both studies were retrospective – looking back at success rates of patients who had transplants performed. One study involved patients who had a simultaneous kidney-pancreas transplant, and the other involved patients receiving a kidney transplant alone.
Ideal pancreas donors are between the ages of 10 and 40 years, weigh between 60 and 180 pounds, and die in the hospital from a head injury. Because of the strict criteria for pancreas donors, the pancreas is recovered in only 20 to 25 percent of organ donors nationally.
Stratta's study defined extreme kidney-pancreas donors as those who were either older than 50 or younger than 8 years, or who died after their heart stopped. People with cardiac death are often considered inappropriate for pancreas donation because their organs may become damaged from being oxygen-deprived.
With a mean followup of 17 months, the average organ survival rate in patients who received a pancreas from an extreme donor was 89 percent. The organ survival rate in the conventional group, which had a mean followup of 22 months, was 77 percent. Patient survival rates were 100 percent in the extreme donor group and 93.5 percent in the conventional group. There were no significant differences in length of hospital stay, incidence of acute rejection, infection or surgery complications. The study involved 31 transplants from conventional donors and nine transplants from extreme kidney-pancreas donors.
"Our results suggest that the pancreas donor criteria can be liberalized to include selected female donors who are over 50 years of age, pediatric donors, and donation after cardiac death without incurring any adverse short-term outcomes," said Stratta. "These short-term results are significant because they are comparable to the already excellent results achieved from standard or more conventional pancreas donors."
The second study involved patients who received kidneys from extreme ECDs between October 2001 and November 2004. Extreme ECDs were defined as deceased donors who were at the outer limits of acceptability including being older than 70 years, having high levels of a protein called creatinine, which is used to determine kidney function, dying from cardiac arrest prior to organ donation, or prolonged storage time for the organ.
The researchers compared 32 kidney transplants involving conventional ECDs with 42 from extreme ECDs. After a mean followup of 18 months, kidney survival was 83 percent in the extreme ECD group and 84 percent in the conventional ECD group. Patients in the extreme ECD group had an average survival of 95 percent, compared to 86 percent in the conventional ECD group. Renal function was comparable in both groups.
"The limits of donor acceptability continue to evolve as excellent short-term outcomes can be achieved in kidney transplants from extreme donors. More importantly, patients are waiting less time to receive a life-saving kidney transplant and become dialysis-free," said Stratta.
Source: Eurekalert & othersLast reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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