Baltimore, MD - A new study has found that renal transplants in black patients appear to be more successful if the donor is black and has died of cardiac causes rather than brain death [1]. The findings are somewhat unexpected, because white patients seem to do better if they receive a kidney from a brain-dead rather than cardiac-death donor. Dr Jayme E Locke (Johns Hopkins University, Baltimore, MD) and colleagues report their findings online July 23, 2008 in the Journal of the American Society of Nephrology.

Coauthor Dr Daniel S Warren (Johns Hopkins University) told heartwire: "This highlights how little we know about the molecular consequences of cardiac and brain death as it pertains to transplantation. It's fairly interesting that seemingly the best organ for a white recipient is a white brain-dead donor and the best organ for a black recipient is from a black cardiac-death donor."

Locke added, "Using cardiac-death donors is a relatively new thing. Initially people were concerned that kidneys from cardiac-death donors wouldn't be ideal. But multiple studies have now shown you can achieve outcomes with cardiac-death donor kidneys that are essentially the same as outcomes with organs from brain-dead donors, as long as certain criteria are adhered to. People are beginning to realize that, particularly with young donors who die of cardiac death, you can achieve pretty excellent results."

"Optimization of this untapped donor source could dramatically increase the number of kidneys available for transplantation each year," the researchers conclude.

Locke and colleagues explain that black patients, despite making up almost 35% of the transplant waiting list, are currently two times less likely to receive a kidney transplant than their white counterparts.

And many studies have shown that black recipients are more likely to experience graft failure than whites; this disparity in outcome exists even after socioeconomic factors are controlled for. In addition, kidneys from black deceased donors have a 1.64-fold higher risk for graft loss compared with those from white donors.

In their new study, Locke et al looked at the outcomes of more than 100 000 adults who received a deceased-donor transplant between 1993 and 2006 and were included in the United Network for Organ Sharing (UNOS) database.

They identified 142 black recipients of kidneys from black cardiac-death donors. Compared with standard-criteria kidneys from white donors after brain death, kidneys from black donors after cardiac death conferred a 70% reduction in the risk for graft loss (adjusted hazard ratio 0.30, 95% CI 0.14-0.65; p=0.002), and a 59% reduction in risk for death (adjusted HR 0.41; p=0.02).

"There are two main messages," Locke told heartwire. "One is that outcome with cardiac-death donors appears to be less racially disparate than outcomes with brain-death donation. Second, and more specifically, black recipients achieve the best long-term kidney graft survival when they receive a kidney from a black donor who had a cardiac death."

She added: "In 2005, the Institute of Medicine found that, in the US, there were 22 000 potential cardiac-death donors, yet if you look at kidney transplants, we performed less than 600, so these results provide more evidence demonstrating that cardiac-death kidneys can perform as well as, and in some cases slightly better than, brain-death organs. What I'm hoping is that this will encourage more organ donation."

If we were to say . . . black recipients should wait for a kidney that comes from a black donor who died of cardiac death, the black recipient would be disadvantaged by that.

"Increased recovery of organs donated after cardiac death from black donors may . . . mitigate existing racial disparities and improve outcomes for black renal-transplant recipients," the researchers say.

But they also warn that their data are preliminary. Warren notes, "We have a sentence in the paper where we specifically argue against using this information to direct patient-level decisions or to alter current allocation algorithms, simply because of how few black recipients have ever received a black cardiac-death organ."

"In the current environment, there is still an organ-shortage crisis," Locke explains. "So if we were to say, based on this data, black recipients should wait for a kidney that comes from a black donor who died of cardiac death, the black recipient would be disadvantaged by that. We all know that getting a kidney transplant is much better than staying on dialysis, no matter what donor."