After accounting for human leukocyte antigen (HLA) mismatch and other factors, survival of living-donor kidney allografts is longer for transplants from unrelated donors compared to related donors—particularly for Black or African American donor-recipient pairs, reports a study in JAMA Network Open.
The researchers analyzed 72,980 adult living-donor kidney transplants, identified using Organ Procurement and Transplantation Network data from 2000 through 2014, with follow-up to 2020. The median donor age was 41 years; 60% were women. In 59% of transplants, donors and recipients had some degree of biologic relationship.
Rates of death-censored allograft failure were compared for biologically related and unrelated pairs, with adjustment for number of HLA mismatches and other characteristics, including primary diagnosis of cystic kidney disease and donor race (African American versus non-African American).
Donors in biologically related pairs were younger (39 versus 44 years), less likely to be women (58% versus 64%), and less likely to be White (62% versus 77%). Recipients in related pairs were younger (48 versus 50 years), more likely to be women (42% versus 35%), and less likely to have cystic kidney disease (6% versus 15%). Biologically related pairs had fewer HLA mismatches: 3 versus 5.
Allograft failure occurred in 17% of unrelated and 19% of related transplants; recipient death rates were also 17% and 19%, respectively. After adjustment for HLA mismatch, the rate of death-censored allograft failure was significantly higher for the biologically related pairs: hazard ratio (HR) 1.26.
The association was attenuated but remained significant after adjustment for donor and recipient characteristics (HR 1.06) and study era (HR 1.05). On analysis stratified by donor race, the increase in death-censored allograft failure was significant only for transplants from African American donors: HR 1.12.
The proportion of living-donor kidney transplants in the United States has increased substantially over the past 2 decades. The effects of this trend on allograft outcomes remain unclear.
The new analysis shows a higher allograft failure rate among recipients of living-related kidney transplants from biologically related donors. The association persists after accounting for donor and recipient characteristics, including HLA mismatch. “These findings suggest that kidney donors who are related to their recipients may share genetic or socioenvironmental predispositions to kidney disease that shorten allograft longevity,” the researchers write [Husain SA, et al. Association between donor-recipient biological relationship and allograft outcomes after living donor kidney transplant. JAMA Netw Open 2021; 4:e215718. doi: 10.1001/jamanetworkopen.2021.5718].