Virtual Crossmatching in Kidney Transplantation: The Wait Is Over

Flow cytometric crossmatching is currently the method of choice for most transplantation programs before kidney transplantation. In July of 2017, our program implemented the virtual crossmatch, without a prospective physical crossmatch, for the majority of patients in the setting of a new kidney allocation system implemented by the United Network for Organ Sharing.

A retrospective review was conducted to determine whether virtual crossmatching could reduce cold ischemia time (CIT). Secondary outcomes included the incidence of delayed graft function and 1-year patient and allograft failure.

A total of 825 patients received a kidney transplant between December 1, 2014 and July 1, 2018; 505 were in the pre-implementation group and 227 were in the post-implementation group. The CIT decreased between the pre-implementation era to post implementation era from 16.67 ± 8.7 hours to 14.5 ± 8.2 hours (p = 0.002). On univariate analysis, delayed graft function (DGF) rates were similar between the 2 eras (19% vs 17%; p = 0.415), despite having more donations after cardiac death and higher Kidney Donor Profile Index donors in the post-implementation era. There was no difference in biopsy-proven acute rejection (n = 28 [5.6%] vs n = 8 [3.5%]; p = 0.226), 1-year graft loss (4% vs 3%; p = 0.304), or patient death (2% vs 1%; p = 0.567) rate between groups. On multivariable modeling for mean CIT and incidence of DGF, patients receiving transplants in the post-implementation era had an adjusted reduction in CIT of an estimated 2.35 hours (95% CI, 1.15 to 3.55; p < 0.001). Patients in the post-implementation era also had 26% lower odds of DGF developing (odds ratio 0.74; 95% CI, 0.48 to 1.14; p = 0.170), after adjusting for covariates.

Kidney transplantation can be safely performed with virtual crossmatching, without a prospective physical crossmatch with improved CIT and potentially reduced DGF rate without increased risk of rejection.