Factors that are typically not considered during a kidney transplant — specifically, differences in weight and sex between the donor and recipient — may have a significant impact on the ultimate viability of the new organ and health of the patient.
Researchers from Dalhousie University in Canada discovered that mismatched weight can result in up to a 50 percent increased risk of organ failure in the person receiving the kidney transplant, according to new research appearing in the Clinical Journal of the American Society of Nephrology.
While the researchers found that all mismatched groups see an elevated risk, one group stands out — namely, women who receive a kidney from a male donor who weighs significantly less than the recipient.
“This study is extremely important because we have shown that when all else is considered, something as simple as the combination of a kidney donor’s weight and sex is associated with a marked increase in kidney transplant failure,” said lead author Dr. Amanda Miller.
Across both sexes, the researchers found that kidney recipients who were about 66 pounds heavier than their respective donors had a 28 percent greater risk of kidney failure compared to recipients and donors who were closer in weight.
Men receiving kidneys from women who weighed significantly less had a 35 percent increased risk of organ failure.
“After multivariable adjustment, the highest relative hazards for graft failure were observed for female recipients of male donor kidneys and male recipients of female donor kidneys in situations where the recipient” was approximately 66 pounds larger than the donor, report the study authors.
Adding to the Matching Protocol
About 100,000 people receive a kidney transplant every year, according to national health statistics. The vast majority of transplants prove successful — about 95 percent of kidney recipients are alive after one year of receiving the new organ.
Yet with more than 660,000 Americans experiencing kidney failure, the need for well-matched transplants is abundantly clear. About 47,000 people die from chronic kidney failure every year, according to the National Institute of Diabetes and Digestive and Kidney Diseases.
While the new research sheds light on the complex variables that make a good match for organ donation, the researchers believe that their work is just a small step in the right direction. “While more research is required before including these variables in a recipient matching strategy, this study highlights the importance of donor and recipient matching above and beyond current immunology-based protocols,” said Miller.
In an editorial accompanying the new study in the Clinical Journal of the American Society of Nephrology, researchers who were not involved in the study caution that adding stricter protocols to the organ-matching system might lead to harmful consequences for a large number of patients.
For instance, the medical community would be tasked with complex matching in an already complex system. Furthermore, “restricting transplant options by prioritizing sex matching may also lead to longer waiting times,” wrote the researches in the editorial. “Females with a large body size would be particularly disadvantaged by an approach that favored allocation of sex- and body-size matched kidneys.”