Three risk factors: donor age; the length of time an organ is cooled between procurement and transplantation; and how urgently the recipient needs the transplant; have the greatest impact on patient and graft survival rates for liver transplantation, according to an article in the March issue of Archives of Surgery.
Almost 2,000 people with end-stage liver disease die every year waiting for a suitable donor liver, according to background information in the article. In 2000, there were almost 17,000 candidates awaiting liver transplant and only 5,000 transplanted. In an effort to expand the donor pool, organs from donors that are not judged optimum for a variety of reasons are being considered for possible transplant. Determining which factors have the most impact on patient and graft survival rates could help increase the donor pool and shorten the wait for liver transplantation, the authors suggest.
Derek E. Moore, M.D., of the Vanderbilt University Medical Center, Nashville, Tenn., and colleagues reviewed data on all adult patients who underwent liver transplant for end-stage liver disease at Vanderbilt University Medical Center between January 1, 1991 and July 31, 2003 to determine which of a number of previously identified risk factors had the greatest impact of the survival of the graft (the transplanted liver) and the survival of the patient. The researchers included three categories of risk factors in their analysis: donor characteristics, including age (whether the donor of the liver was older than 60) and weight (donor weight of more than 220 lbs.); technical characteristics, including cold ischemia time (CIT, the length of time an organ is cooled between procurement and transplantation) equal to or greater than 12 hours, and graft to recipient sex mismatch (female graft to male recipient); and recipient risk factors, including the United Network for Organ Sharing (UNOS) urgency status (1 or 2A versus 2B or 3), age and the cause of liver disease.
Based on their statistical models, the researchers found that donor age of 60 years and older, cold ischemia time of 12 hours or more and urgent recipient status were independent risk factors for shortened graft survival and for shortened patient survival. "Five year graft survival was 72 percent for recipients of donors younger than 60 years and 35 percent for recipients of donors 60 year or older," the authors write. "A CIT of 12 hours or more was associated with shorter five-year graft survival (71 percent versus 58 percent). Five-year graft survival for UNOS status 2B or 3 was 71 percent versus 60 percent for status 1 or 2A."
"On the basis of these hypothetical models, a graft transplanted from a donor younger than 60 years into a status 2B or 3 recipient with less than 12 hours of cold ischemia would have a probability of 75 percent for surviving five years," the authors write. "In contrast, a graft from a donor 60 years or older transplanted into a status 1 or 2A recipient with a CIT of 12 hours or more would have only a 20 percent probability of surviving five years after transplant." The authors demonstrate similar findings for increasing donor age, cold ischemia time and urgent UNOS status on patient survival.
"From these findings, we can develop preliminary models of pretransplant characteristics to help predict postransplant survival," the authors conclude. "In future studies we hope to confirm our model in the UNOS database and formulate a clinically relevant pretransplant model by using easily accessible variables that will accurately predict postransplant and patient survival. Such a model could be used to make recipient-specific organ allocation decisions at the time of graft procurement."