Comparing outcomes of third and fourth kidney transplantation in older and younger patients.

Performing third or fourth kidney transplantation (3KT and 4KT) in older patients is rare due to surgical and immunologic challenges. We aimed to analyze and compare the outcomes of younger (18-64 years) and older (≥65 years) recipients of 3KT and 4KT. Between 1990 and 2016, we identified 5816 recipients of 3KTs (153 were older) and 886 recipients of 4KTs (18 were older). The incidences of delayed graft function (24.3% vs. 24.8%, p = .89), primary non-function (3.2% vs. 1.3%, p = .21), 1-year acute rejection (18.6% vs. 14.8%, p = .24), and 5-year death censored graft failure (DCGF) (24.8% vs. 17.9%, p = .06) were not different between younger and older recipients of 3KT. However, 5-year mortality was higher in older recipients (14.0% vs. 33.8%, p < .001) which remained significant after adjustment (aHR = 3.21, 95% CI: 2.59-3.99). Similar patterns were noted in the 4KT cohort. When compared with waitlisted patients, 3KT and 4KT are associated with a lower risk of mortality; aHR = 0.37, 95% CI: 0.33-0.41 and aHR = 0.31, 95% CI: 0.24-0.41, respectively. This survival benefit did not differ by recipient age (younger vs. older, p for interaction = 3KT: .49 and 4KT: .58). In the largest cohort described to date, we report that there is a survival benefit of 3KT and 4KT even among older patients. Although a highly selected cohort, our results support improving access to 3KT and 4KT.