University of Virginia Health System

U.Va. Study Challenges Conventional Theories On Racial Differences In Kidney Transplant Outcomes

Because African-Americans experience more episodes of rejection than Caucasians, many physicians give them higher levels of immunosuppressant drugs to prevent rejection. Unfortunately, these drugs can have potential side effects.

But the findings, presented in May at the American Society of Transplant Physicians annual meeting in Chicago, challenge the conventional theory that increased episodes of rejection are responsible for the significantly higher rate of kidney failure in African-Americans who have undergone kidney transplant.

Our study shows that when you control for episodes of rejection, African-Americans still have significantly poorer outcomes than Caucasians, said Dr. Ross Isaacs, assistant professor of clinical internal medicine at the University of Virginia Health System and lead author of the study. And since the drugs themselves are associated with a higher risk of infection and malignancies, we need further studies to assess whether the current practice of giving more immunosuppressants is warranted.

In addition, the analysis showed that other factors commonly thought to contribute to poorer outcomes among African-Americans following kidney transplants, such as higher incidences of hypertension and diabetes and genetic compatibility of the donor, actually were not associated with the poorer outcomes.

In the study, the researchers analyzed data from the United Network for Organ Sharing Scientific Registry on more than 14,000 patients who underwent a kidney transplant from a living related donor between 1988 and 1994. First the data was analyzed for organ survival following kidney transplant by race alone, which showed that African-Americans have a 79 percent greater chance of organ failure following kidney transplant than Caucasians.

Then researchers analyzed the same data adjusting for 12 risk factors, including existence of hypertension, existence of diabetes, gender, genetic compatibility and episodes of early rejection. They found that when all 12 risk factors were controlled for, the African-American race was associated with a 65 percent greater chance of organ failure following kidney transplant as compared to the risk in Caucasians.

Regardless of the many variables we assessed, we were not able to remove the association between race and outcomes, Isaacs said. This suggests that some other factor or factors are responsible for the differences in outcomes between blacks and whites following kidney transplant. We're now trying to determine what these factors are, so that ultimately we can reduce or eliminate any racial differences in outcomes.

June 19, 1998