Choosing the Best Kidney for Transplantation
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Organ transplantation is subject to the law of supply and demand – in which demand for organs far outweighs supply from both living and deceased donors.
But results from a new, nationwide Scientific Registry of Transplant Recipients (SRTR) study led by University of Michigan Health System researchers may offer new hope to some patients with end-stage renal disease waiting for a kidney transplant.
The study found that the growing use of organs from expanded criteria donors (ECD) – older donors and those with certain pre-existing kidney or other medical problems whose kidneys were often not used in the past – is not only adding to the pool of kidneys available for transplantation, but also increasing the chances for survival for certain patients with end-stage renal disease depending on their age, how long they would need to wait for a donor organ, and the severity of their kidney disease.
Results from this study are published in the Dec. 7 issue of the Journal of the American Medical Association (JAMA).
Currently, there are more than 64,000 people in the United States awaiting a kidney transplant. With the need for kidneys increasing and the number of available kidneys from deceased donors failing to keep pace, patients may wait years for a healthy, or non-ECD, kidney to become available.
But many can’t afford to wait. So more patients are turning to ECD kidneys, despite a higher risk for organ failure, in lieu of staying on dialysis while waiting for a healthier kidney to become available, says lead author Robert M. Merion, M.D., professor, Department of Surgery at the U-M Medical School.
“The real challenge has been determining which patients would benefit most by taking the ECD kidney now and which ones would be better served by waiting for a healthier kidney for transplantation,” says Merion, the clinical transplant director for the SRTR, which is administered by the University Renal Research and Education Association (URREA), an independent not-for-profit research organization, and supports the ongoing evaluation of the scientific and clinical status of solid organ transplantation in the United States.
Co-author Robert A. Wolfe, Ph.D., professor emeritus of biostatistics at the U-M School of Public Health continues: “We calculated the average lifetime for patients who accept an ECD organ compared to those who remained on dialysis with the option of accepting a non-ECD transplant at a later time, in order to help patients choose between these options. The answer depends upon the patient’s situation, so different patients might make different choices based on their particular situation and their willingness to trade off an earlier transplant with an ECD kidney versus a higher chance of failure of the transplant.”
To gauge which patients are better off opting for an ECD kidney transplant now rather than waiting for a non-ECD kidney, Merion and his colleagues measured the outcomes of patients on dialysis from the day they were placed on the organ wait list. The study looked at all of the patients in United States – a total of 109,127 people – who were on dialysis for kidney failure and had been added to an organ wait list between 1995 and 2002, and then followed their progress through July 2004.
Factors such as age, gender, ethnicity, the cause of the patient’s kidney disease, and the local wait time for a non-ECD kidney were all taken into account. Outcomes for patients who did not receive a transplant or got a non-ECD kidney were then combined and compared against patients who had an ECD kidney transplant.
By the end of the study, 7,790 candidates received an ECD kidney transplant, 41,052 received a non-ECD deceased donor transplant, 15,203 received a living donor transplant, and 45,082 either died before receiving a transplant or were still waiting for a donor kidney.
Overall, recipients of ECD kidney transplants had a 17 percent long-term lower risk of dying when compared with those who remained on dialysis or eventually received a non-ECD transplant. However, not all patients were found to enjoy this benefit.
ECD kidneys were shown to have the greatest benefits, in terms of survival, for patients over the age of 40 and those who would need to wait more than 44 months for a non-ECD kidney to become available. Only diabetic patients were found to benefit from ECD kidneys in areas where wait times were shorter. For patients younger than 40, there was no significant advantage to accepting an ECD kidney.
In general, two main groups of patients emerged as the best recipients of ECD kidneys: patients with long projected wait times and/or limited access to donor kidneys, and those with kidney failure due to diabetes, which can lead to death from other medical complications, such as heart attack or stroke.
“ECD kidneys are clearly a good solution in certain situations,” says Merion. “This study’s results allow us, with greater clarity than before, to maximize the benefits of ECD kidneys for patients, and match patients with a transplant option that will offer them the best chance for survival.”
Merion notes that the study provides useful new information that transplant physicians can use to counsel patients entering the wait list for organs.
While this study focuses on survival rates of kidney transplant patients, Merion says future research needs to be done to address quality of life issues for patients who remain on dialysis and those who opt for an ECD kidney transplant.
Along with Merion and Wolfe, Valarie B. Ashby, M.A., and Tempie E. Hulbert-Shearon, M.S., of the U-M Department of Biostatistics and the SRTR of Ann Arbor; Dale A. Distant, M.D., of the Department of Surgery, State University of New York Health Sciences Center at Brooklyn; Robert A. Metzger, M.D., of TransLife-Florida Hospital Medical Center; Akinlolu O. Ojo, M.D., Ph.D., of the U-M Department of Internal Medicine; and Friedrich K. Port, M.D., MS, of the University Renal Research and Education Association, co-authored the study.
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