Virtual Crossmatching in Kidney Transplantation: The Wait Is Over

Abstract

Background: 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.

Study design: 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.

Results: 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.

Conclusions: 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.