By Margarita Nahapetyan
People who give the gift of life by donating a kidney not only lead long and healthy lives, but also have fewer kidney problems than the general population.
"We've suspected all along that kidney donation is a safe practice, but there has never been a long-term study with large numbers of patients in the United States," said Dr. Hassan N. Ibrahim, an associate professor of medicine at the University of Minnesota, who led the first U.S. study to compare the survival of kidney donors to that of the general public.
The research studied outcomes on the 3,698 people, who donated their kidneys, at the University of Minnesota between 1963 and 2007. Health of kidney donors was compared to a similar number of healthy patients of the same age, gender and body weight. In addition to health in general, the study also focused on measures of kidney function, such as the glomerular filtration rate (the flow of filtered fluid through the kidney, as well as the existence of other conditions, such as high blood pressure.
The scientists found that the life quality of kidney donors was 60 per cent better than that of the people in the general population of the same age and gender. "Their lifespan is comparable to others of the same age, gender and ethnic background," said Dr. Ibrahim, "Indeed, it appears that kidney donors might actually have better survival." It was also noted that kidney donors have perfect glomerular filtration rates 85 per cent of the time, and that they have less chance of developing high blood pressure, or have protein in the urine. End-stage kidney failure developed only in 11 of the donors over the years. That is a rate of 180 cases per million people per year to compare with the rate of 268 cases per million people per year in the general population.
The good results most likely reflect the strict criteria that was used to choose the donors, the researchers said. The donors had to be in a good health, with no kidney problems, and be free of high blood pressure and diabetes, which are known as the two main causes of kidney failure. "We think these donors do extremely well because they were screened very well," said Dr.Ibrahim. Two previous, smaller researches, which were conducted in Norway and Sweden, showed similar results, but the health of donors was not measured at such detailed level as in this latest study. The scientist also said that he hopes the outcomes will increase donations and encourage transplant centers to continue to carefully select donors and not relax their requirements.
Dr. Jane Tan and Dr.Glenn Chertow, of Stanford University School of Medicine wrote an accompanying editorial to the study. The noted that the study donors were mostly white people and were at a younger age than today donors. The results may not apply to older, African-American donors who represent only about 12 per cent of all kidney donors, they said. Dr. Ibrahim and his team hope that a new research which is about to start could fill in that gap. Conducted in collaboration with the Mayo Clinic and the University of Alabama, the research will examine more than 8,000 kidney donors, many of them black people. "We hope to have results in two to three years," Ibrahim said. "It is clear that the excellent results seen here reflect very strict criteria. Transplant centers now are willing to consider older donors and people with mild hypertension." That could mean that in decades to come the outcomes for these less-healthy donors "might look different," concluded the expert.
Kidneys are the most commonly transplanted organ in the United States. Living donation has increased as more people became willing to donate and newer surgery techniques have made a recovery time much shorter and easier for patients.. Nearly 9,000 kidney transplants were performed last year with organs from deceased donors, and nearly 5,000 kidney transplants came from living donors, according to the United Network for Organ Sharing (UNOS).
Kidneys filter waste and excess fluid from our blood. In case of their failure, the options left are dialysis or a transplant. Dialysis is not really a good substitute as it does not fulfill many of the secondary functions of the kidney, such as the production of hormones. More than 78,000 people are on the national waiting list to receive a kidney from a deceased donor. But the need of kidney transplantation is growing drastically because of sharp increases in diabetes and high blood pressure. As a result, nearly 20 per cent of dialysis patients die every year.
The study was reported in the Jan. 29 issue of the New England Journal of Medicine.