By JEREMY SINGER-VINE
A major study of kidney donations provides the strongest evidence yet that organ donors live just as long as people who go through life with two kidneys.
Medical specialists say they plan to tout the findings in transplant literature to encourage more people to become living donors. Of the roughly 13,600 kidney transplants performed in the U.S. last year, 6,387 were from living donors, with the balance coming from deceased donors. A living kidney donation extends a recipient’s life span by 17 years on average, compared with nine to 11 years when a kidney from a deceased donor is used. More than 84,000 U.S. patients are currently waiting for a kidney transplant.
The study, published this month in the Journal of the American Medical Association, “reconfirms what many of us have suspected, that living donation is a safe process for donors,” says Matthew Cooper, director of kidney transplantation at the University of Maryland Medical Center, who wasn’t involved in the study.
The study also seems to affirm the resilience of a healthy kidney, whose functions include filtering metabolic waste and regulating blood pressure. When people have two, normally functioning kidneys, neither works at full capacity, past research has shown. After one of the organs is removed, the remaining kidney picks up the slack—it grows 20% to 25% larger and becomes 20% to 30% more efficient over the next six months. “That seems to be more than sufficient in the vast majority of donors,” says Bryan Becker, president of the National Kidney Foundation and a nephrologist at the University of Wisconsin.
The research, conducted at Johns Hopkins University, looked at all 80,347 living kidney donations in the U.S. between 1994 and 2009. Its findings generally support earlier studies involving relatively small numbers of kidney donors at individual transplant centers.
Among the latest findings, in the 90 days after surgery, 3.1 of every 10,000 donors died, a mortality rate about eight times higher than non-donors experienced, but still quite low compared to similar procedures. Over the longer term, however, donors died no more often than the control group, based on death data obtained from the Social Security Administration.
Though the researchers didn’t measure donors’ quality of life, smaller studies have found that kidney donation doesn’t increase the risk of diabetes, stroke, cancer or heart disease. In fact, donors appear to have lower cholesterol and blood pressure.
For every successful transplant, scores of potential living donors begin the process. Most are immediate family of the recipient. But transplant centers are increasingly accepting non-blood-related donors, such as spouses, close friends and so-called altruistic donors, who offer to donate a kidney with no particular recipient in mind.
Candidates are screened for diabetes, high blood pressure, a history of kidney infections and other factors that would make life perilous with one kidney. An independent counselor ensures that the candidate is psychologically stable and hasn’t been coerced into donation. At any point during the process, the candidate can withdraw.
There are a number of reasons that potential kidney donors may choose not to go through with the procedure, ranging from concerns about their own well being to financial considerations. Although donors incur no out-of-pocket medical expenses, transplant centers don’t cover peripheral costs like travel or lost wages. Some candidates fear they’ll face higher insurance premiums if the screening process reveals a health condition, or the surgery creates one.
Perhaps 10% to 20% of candidate donors withdraw for non-medical reasons, estimates Raymond Heilman, a Mayo Clinic nephrologist. The true rate is difficult to determine, as transplant centers closely guard potential donors’ privacy. Many transplant centers offer a “medical out,” citing a nonexistent condition like high blood pressure, to shield dropouts from familial pressure to donate.
Last year, living kidney donations saw their first annual increase in five years, to 6,387 from 5,968 a year earlier, after peaking in 2004 at 6,647. In efforts to make donating a kidney safer, nephrologists are increasingly adopting new procedures such as laparoscopy, an alternative to open kidney surgery. They also are seeking to do more with the existing pool of potential donors. Transplant centers are compiling a national database to help arrange complex swaps between multiple donors and recipients, aimed at finding biological matches more quickly for patients on the waiting list.