For years, medical studies have reached the same conclusion: African-American patients do better on kidney dialysis than their white counterparts. But new Johns Hopkins research, published in the Journal of the American Medical Association, shows that younger blacks -- those under the age of 50 -- actually do much worse on dialysis than equally sick whites who undergo the same blood-filtering process.
The findings -- called "surprising" by the research team -- could have a serious impact on long-held practices guiding who gets referred for lifesaving kidney transplantation and who remains on dialysis indefinitely.
Previous research on this issue, according to the Hopkins team, has been based on analysis of racial differences in dialysis outcomes for all patients with end-stage kidney disease, a majority of whom are over the age of 50.
The new analysis continues to show a survival benefit for black patients over 50, though not a large one. But when the investigators looked at racial differences stratified by age, they found that the population-based analyses were camouflaging the fact that younger black patients do much worse on dialysis than white patients with a similar health status.
Specifically, results of the new study of 1.3 million patients with end-stage kidney disease, led by Dorry L. Segev, M.D., Ph.D., an associate professor of surgery at the Johns Hopkins University School of Medicine, show that black patients between the ages of 18 and 30 are twice as likely to die on dialysis than their white counterparts; and those ages 31 to 40 are 1.5 times as likely to die.
"As a medical community, we have been advising young black patients of treatment options for kidney failure based on the notion that they do better on dialysis than their white counterparts," Segev says. "This new study shows that, actually, young blacks have a substantially higher risk of dying on dialysis, and we should instead be counseling them based on this surprising new evidence."
Dialysis, a life-sustaining process for removing waste and excess water from the blood, acts as an artificial replacement for lost kidney function in people with renal failure. The grueling and inconvenient process takes many hours several times a week, usually in a specialized center, preventing many from working, going to school, or caring for their families.
It is possible that because of the long-held belief that black patients did better on dialysis, fewer black patients of all ages are referred for transplants, Segev says. In patients ages 18 to 30, the study found that 55 percent of white patients got new kidneys during the study period of 1995 to 2009, while only 32 percent of comparable black patients got transplants. Meanwhile, 28 percent of young black patients died on dialysis during the study period and only 14 percent of white patients died.
Segev, a transplant surgeon, says the results raise new questions about why this racial disparity in outcomes occurs at all. It is possible, he suggests, that the differences could be attributed to the lower socioeconomic status of many young African-Americans, who are less likely to have good insurance and may receive inadequate or no health care at the earlier stages of their disease. There is also the possibility that there are biological reasons for the disparity, perhaps involving hypertension, which is more prevalent and often more aggressive among African-Americans.
Whatever the causes, Segev says the medical profession needs to make sure young black patients understand that they are unlikely to do better on dialysis. Also, more African-Americans need to be referred for transplants, he says.
"The next important step is to try to figure out why there is such a high relative risk of death for young black patients on dialysis," says Lauren M. Kucirka, Sc.M., a Hopkins epidemiologist and another study author .
The study was funded by the National Institutes of Diabetes and Digestive and Kidney Diseases and by a Paul Beeson Career Development Award, co-funded by the National Institute of Aging and the American Federation for Aging Research.
Other Johns Hopkins researchers involved in the study include Morgan E. Grams, M.D., M.H.S.; Justin Lessler, Ph.D.; Erin Carlyle Hall, M.D., M.P.H.; Nathan James, Sc.M.; Allan B. Massie, M.H.S.; and Robert A. Montgomery, M.D., D.Phil.