-->

Nov. 6, 2002 -- People who receive an organ donated by a woman may be more likely to suffer complications, organ rejection, or even death after an organ transplant. A major new study shows that organs from female donors tend to fare worse than those donated by males, but the risks vary depending on the type of organ and the age of the donor.

Experts say the results confirm the findings of several smaller studies and suggest that a transplant patient's gender and the gender of the organ donor should be considered in determining immunosuppressive drug therapy. Immunosuppressive medications weaken the immune system and are given to all transplants recipients to improve the chances that the body will accept the new organ rather than reject or attack it.

In the study, published in the October issue of the Journal of the American Society of Nephrology, German researchers analyzed information from more than 124,000 kidney transplants, 25,000 heart transplants, and 16,000 liver transplants performed around the world.

They found that the risk of a male patient losing a transplanted kidney was 22% higher if the donor kidney came from a female rather than a male. Women who received a kidney from female donor also faced a 15% higher risk of an unsuccessful transplant. This gender effect was even more pronounced if the donor was younger (16 to 45 years) rather than older, and was also evident in kidney transplants among matched siblings.

Men and women who received kidneys donated by females also faced a slightly higher risk of death.

For heart transplants, the gender difference was found only among men who received organs donated by females. The study found men who received female hearts were 13% more likely to lose the heart compared to those who got male-donated organs.

Researchers say gender also seemed to play a role in the success of liver transplants, but the findings were less clear. Overall, data collected from transplants performed around the world showed that gender didn't seem to matter. But when the authors isolated the data from North America, they found female-donated livers that were transplanted into male patients were less likely to succeed than male-donated livers.

Researcher Martin Zeier, MD, of the department of internal medicine at the University of Heidelberg in Germany and colleagues say that sex differences related to how the immune system responds to a transplant may explain the findings. Previous research has suggested that women mount a much stronger immune response to transplanted organs than men.