“Heart size would seem to be the most obvious factor; beyond that, no one knows why sex matching is important to transplant survival,” said Eric Weiss, M.D., first author of the study and a post doctoral research fellow in the Division of Cardiac Surgery at The Johns Hopkins University Medical Institutions in Baltimore, Md. “In clinical transplantation, we generally don’t assume that organs from male and female donors have inherent differences affecting long-term outcomes, but our data suggest that there are important differences which must be taken into account.”

Researchers analyzed data from the United Network of Organ Sharing (UNOS), identifying 18,240 patients who received their first orthotopic (replacing a failing organ with a healthy one) heart transplant between 1998 and 2007. In this dataset, patients were followed for 10 years, with the average follow-up time being 3.4 years.

Patients were sorted into four groups: male donor with male recipient, female donor with male recipient, male donor with female recipient, and female donor with female recipient.

Overall, 71 percent were matched by gender to their donor (77 percent of male recipients and 51 percent of female recipients). Twenty-five percent of patients died during the study.

Matching donor and recipient by gender resulted in:

• 13 percent lower risk of graft rejection within the first year;
• 14 percent lower rate of graft rejection over the study period;
• 25 percent drop in 30-day death rate; and
• 20 percent lower one-year death rate.

Statistical modeling revealed that the greatest chance for death during the study occurred when pairing a male donor with a female recipient, which made the risk of death an estimated 20 percent higher compared to a male donor with male recipient. The most successful transplants occurred between male recipients and male donors, when the cumulative chance for survival was 61 percent.

“These results fit with our hypothesis that sex matching in heart transplantation leads to improved survival rates,” said Weiss, the Irene Piccinini Investigator in Cardiac Surgery. “We hypothesized that we would see a big difference in the short-term survival — which we did, most likely because of heart-size issues — but what was interesting was the substantial difference in the long term, as well.”

More than 2,000 transplant surgeries are done each year. Almost 87.5 percent of male recipients and 85.5 percent of female recipients live for more than a year after the transplant, according to American Heart Association statistics.

“We don’t recommend that patients wait longer for a same-sex organ,” Weiss said. “Clearly receiving a heart transplant from a donor of opposite sex is preferable to severe heart failure. If equivalent donors exist for a given patient, our data suggest that picking a sex matched donor may lead to improved short- and long-term survival.”

Co-authors are: Nishant D. Patel, B.A.; Stuart D. Russell, M.D.; William A. Baumgartner, M.D.; Ashish S. Shah, M.D.; and John V. Conte, M.D. Individual author disclosures can be found on the abstract.

A Health Resources and Services Administration contract and a Ruth L. Kirschstein National Research Service Award from the National Institutes of Health funded the study.

Note: If no author is given, the source is cited instead.

• Heart Disease
• Hair Loss
• Erectile Dysfunction
• Chronic Illness
• Fertility
• Men's Health

• Liver transplantation
• Kidney transplantation
• Transplant rejection
• Organ transplant
• Skin grafting
• Bone marrow transplant