OBJECTIVE(S): A variety of risk factors influence the survival of transplanted kidneys and their hosts. We tested the impact of donor and recipient age by cohorts and covariant risks.
METHODS: We followed more than 108,000 recipients of deceased donor kidneys in the UNOS data base transplanted between 1995 - 2008. Graft, patient survival and rejections were evaluated by uni- and multivariate analysis and compared by age cohorts.
RESULTS: Overall, transplant survival was lowest in elderly recipients. However, when censored for patient’s death with a functioning transplant, graft survival improved with every decade of increasing recipient age, although older recipients had received less well matched and poorer quality organs (5 year graft survival: 67% and 81% in recipients aged 18-29 and > 50; p=0.001). Acute rejection rates decreased with every decade of increasing age (29% and 16% for young and older recipients by 1 year, p<0.0001). In contrast, increasing donor age correlated with more frequent acute rejections (p < 0.001). Moreover, effects of both donor and recipient age on graft outcome became particularly obvious in a combinatorial analysis. Older kidneys had a relative risk of graft loss of > 9 when transplanted into young recipients compared to < 3 in old recipients (p<0.0001).
CONCLUSIONS: Increasing recipient age is associated with improved transplant survival, lower rates of rejection and superior outcome of older donor organs. Physiological and/or immunological aspects of organ and recipient age determine, at least in part, transplant outcome. Those results have implications for optimized utilization of organs and immunosuppression.