BOSTON – Younger age of deceased liver donors appeared to improve patient and graft survival when donors and recipients were both of younger age, but not when younger donor livers went to older recipients, according to a secondary analysis of the Organ Procurement and Transplantation Network national database from 2002 to 2011.
"Matching younger recipients with younger donors appears to be the best strategy in order to maximize life years after liver transplantation. However, before this can be considered for allocation policy, much more work needs to be done," including analyses specific to United Network for Organ Sharing regions, Model for End-Stage Liver Disease groups, and modeling of the potential life-years saved with a change in allocation policy, said lead investigator Dr. Neehar D. Parikh of the Comprehensive Transplant Center at Northwestern University, Chicago.
The risk of recipient death is known to increase with advancing donor age, beginning at ages older than 40 years and especially with donors older than 60 years. Also, advancing recipient age has been shown, with some controversy, to affect outcomes negatively, Dr. Parikh said at the annual meeting of the American Association for the Study of Liver Diseases.
Dr. Parikh and his colleagues’ study of the Organ Procurement and Transplantation Network database analyzed 26,849 cases of liver transplantation in which the donor was younger than the recipient, 782 cases in which they were the same age, and 12,107 cases in which the donor was older than the recipient. They also looked at outcomes of patients aged 18-40 years and those 60 years or older, based on the donor age.
As would be expected, recipients had progressively younger mean ages as the donor age increased: 56 years for recipients with younger donors, 52 years for same-age donors, and 48 years for older donors. Hepatitis C virus seropositivity was lowest in recipients who had an older donor (41%), followed by same-age recipient-donor pairs (51%), and recipients who had a younger donor (50%).
In Kaplan-Meier analyses, patient survival at 1 year was significantly worse for those who received a liver from a donor with an older age (86%) or the same age (86%) than from a younger donor (87.4%). Similar results were seen at 3 years between recipients of livers from older (74.5%), same age (73.5%), and younger donors (77.9%).
Older donor age increased the risk for patient death by 14% and graft failure by 13%, in comparison with younger donor age in an adjusted analysis.
For every 10-year increase in patient age for younger donors, the risk of patient mortality increased by 24% and graft failure by 17%. For every 10 years the donor was younger than the recipient, however, there was a 27% decline in the risk of patient mortality and 30% decrease in the risk of graft failure. A small but significance beneficial interaction was found between young donor age and young recipient age on both outcomes.
In contrast, for every 10 years the donor was older than the recipient, the risk of patient mortality increased 9% and the risk of graft failure increased by 22%, and there was no significant interaction between recipient and donor age.
When compared against donor and recipient pairs who were both aged 18-40 years, the risk of patient mortality and graft failure increased significantly for all other combinations of donor and recipient pairs: recipients aged 18-40 years and donors aged 60 years or older (hazard ratios of 1.76 and 1.49, respectively), recipients aged 60 years older and donors aged 18-40 years (HRs of 1.67 and 1.83), and recipients and donors both aged 60 years or older (HRs of 2.12 and 1.87). These results were consistent at both 1 and 3 years.
The overall results "suggest that there is something intrinsic about being older or having an older graft that cannot be remediated by graft or patient age factors," Dr. Parikh said.
The results might be explained in livers from older donors by impaired liver regeneration and increased susceptibility to ischemic reperfusion injury, while older recipients might have decreased circulating stem cells and more competing risks that are not adequately risk adjusted in the available data in older recipients, he said.
One audience member noted that there is still a "huge survival advantage" in all patient populations that receive younger donor livers and that allocating organs based on age is a slippery slope.
Dr. Parikh and his colleagues had no relevant financial disclosures.