Cytomegalovirus matching in deceased donor kidney allocation: Results from a U.S. National simulation model

Background. Cytomegalovirus (CMV) infects >60% of adults and can pose an independent risk factor for allograft loss and mortality in solid organ transplant recipients. The purpose of this study is to evaluate the impact of a nationwide implementation of CMV seromatching (donor/recipient: D−/R− and D+/R+) in the U.S. deceased donor kidney allocation system (KAS). Methods. Adult candidates on the U.S. kidney-only transplant waiting list and deceased donor kidneys offered to the U.S. transplant centers were considered. A discrete-event simulation model, simulating the pre-COVID-19 period from January 1, 2015, to January 1, 2018, was used to compare the performances of currently employed KAS-250 policy (without CMV matching) to various simulated CMV matching policies parameterized by calculated panel reactive antibody exception threshold. Outcomes included CMV serodistribution, waiting time, access to transplantation among various groups, transplant rate, graft survival, kidney discard rate, and antigen-mismatch distribution, stratified by CMV serostatus. Results. CMV matching policy with a calculated panel reactive antibody exception threshold of 50% (namely, the CMV_“>50%” policy) strikes a better balance between benefits and drawbacks of CMV matching. Compared with KAS-250, CMV_“>50%” reduced CMV high-risk (D+/R−) transplants (6.1% versus 18.1%) and increased CMV low-risk (D−/R−) transplants (27.2% versus 13.1%); increased transplant rate for CMV R− patients (11.54 versus 12.57) but decreased for R+ patients (10.68 versus 10.48), yielding an increase in aggregate (11.09 versus 10.94); and reduced mean time to transplantation (by 6 wk); and reduced kidney discard rate (25.7% versus 26.2%). Conclusions. Our findings underscore the feasibility and potential advantages of a nationwide CMV seromatching policy in kidney transplantation.