Machine perfusion of donor kidneys may reduce graft rejection.

Recent evidence suggests that hypothermic machine perfusion of donor kidneys reduces delayed graft function (DGF). This study addresses the effect of machine perfusion (MP) on allograft rejection in the United States. We assembled a retrospective cohort of patients undergoing kidney-alone transplants in the UNOS database from June 30, 2004 to May 31, 2017. DGF was defined as dialysis requirement in the first week post-transplant; graft rejection was defined at 6 months and 1 year. Multivariable logistic regression adjusted for recipient and donor factors evaluated the effect of MP on DGF and graft rejection. Records for 79 300 kidney transplants meeting inclusion criteria were abstracted, 42% of which underwent MP. MP kidneys came from older donors, were more likely to have been obtained following donation after cardiac death, and had longer cold ischemic times. Rates of DGF and rejection were similar between MP and static storage kidneys. Following adjustment, recipients of MP kidneys were less likely to experience rejection at 1 year (OR 0.91 [95% CI 0.86-0.97] P = .002), but not at 6 months post-transplantation (OR 0.94 [0.88-1.02] P = .07). This effect persisted following adjustment for cold ischemic time. This study adds to the accumulating evidence demonstrating improved outcomes following MP of kidneys. We encourage protocolized consideration of MP for kidney grafts.