Liver graft quality significantly poorer with female vs male donors

Last Updated: 2010-11-03 15:56:02 -0400 (Reuters Health)

By Anne Harding

NEW YORK (Reuters Health) - Gender mismatch between donor and recipient does not promote liver transplant rejection, a new analysis including nearly 25,000 patients confirms. However, female donors tend to be older, heavier and shorter than their male counterparts, lowering the quality of their livers for grafting.

Dr. Jennifer C. Lai of the University of California, San Francisco and her colleagues found that while female-to-male transplants were more likely to be rejected, once they accounted for gender differences in donor quality, the effect of gender mismatch disappeared. "The message really is that donor quality is key," Dr. Lai told Reuters Health. She presented her findings at this week's annual meeting of the American Association for the Study of Liver Diseases in Boston.

Previous research had suggested that donor-recipient gender mismatches might make liver transplant rejection more likely, Dr. Lai explained in an interview. However, she added, the importance of donor quality as measured by factors like the donor's cause of death, age, height and race has only relatively recently been recognized. She pointed to her UCSF colleague Dr. Sandy Feng's 2006 report describing a quantitative donor risk index, which has since been validated by other researchers.

To investigate the influence of gender mismatch on graft rejection risk, Dr. Lai, Dr. Feng and their colleagues looked at 24,544 adults who received liver transplants between 2002 and 2007. The recipient cohort contained 16,633 males (68%) and 7,911 females (32%). The donors consisted of 14,568 males (59%) and 9,976 females (41%).

Thirty-six percent of men and 51% of women received a gender-mismatched graft. The risk of graft loss was 1.11 times greater overall with a gender mismatch. But while giving a male donor graft to a female recipient didn't significantly increase the risk of graft loss, female-male mismatches raised the risk by 18% (P<0.001).

The researchers found "clinically relevant" differences in graft quality between male and female donors on six of the 15 characteristics that they evaluated. For example, the average age for female donors was 47, compared to 39 for men, while females' average height was 165 centimeters compared to 178 centimeters for men. Fifty-six percent of the women died of stroke, compared to 34% of men. And 26% of female donors had BMIs above 30, while 20% of males did. The donor risk index was 1.6 for women and 1.3 for men, a 20% difference that Dr. Lai said was "a huge surprise."

Once the researchers took these factors into account, the increased risk of rejection seen with female-male mismatch disappeared. The most important factors were donor age, with a 12% increased risk of rejection for every additional 10 years, and height, with a 6% reduced risk of rejection with every additional 10 cm of height.

"The conversation kind of is over about donor gender mismatch and donor gender, at least for non-hepatitis C infected patients," Dr. Lai concluded.

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