title: Rethinking the advantage of zero-HLA mismatches in unrelated living donor kidney transplantation: implications on kidney paired donation.
abstract: The OPTN/UNOS Kidney Paired Donation (KPD) Pilot Program allocates priority to zero-HLA mismatches. However, in unrelated living donor kidney transplants (LDKT)-the same donor source in KPD-no study has shown whether zero-HLA mismatches provide any advantage over >0 HLA mismatches. We hypothesize that zero-HLA mismatches among unrelated LDKT do not benefit graft survival. This retrospective SRTR database study analyzed LDKT recipients from 1987 to 2012. Among unrelated LDKT, subjects with zero-HLA mismatches were compared to a 1:1-5 matched (by donor age ±1 year and year of transplantation) control cohort with >0 HLA mismatches. The primary endpoint was death-censored graft survival. Among 32,654 unrelated LDKT recipients, 83 had zero-HLA mismatches and were matched to 407 controls with >0 HLA mismatches. Kaplan-Meier analyses for death-censored graft and patient survival showed no difference between study and control cohorts. In multivariate marginal Cox models, zero-HLA mismatches saw no benefit with death-censored graft survival (HR = 1.46, 95% CI 0.78-2.73) or patient survival (HR = 1.43, 95% CI 0.68-3.01). Our data suggest that in unrelated LDKT, zero-HLA mismatches may not offer any survival advantage. Therefore, particular study of zero-HLA mismatching is needed to validate its place in the OPTN/UNOS KPD Pilot Program allocation algorithm.
authors.affiliation: Department of Medicine, University of Florida, Gainesville, FL, USA.
authors.forename: Michael Jin
authors.initials: MJ
authors.lastname: Casey
authors.forename: Xuerong
authors.initials: X
authors.lastname: Wen
authors.forename: Shehzad
authors.initials: S
authors.lastname: Rehman
authors.forename: Alfonso H
authors.initials: AH
authors.lastname: Santos
authors.forename: Kenneth A
authors.initials: KA
authors.lastname: Andreoni
mesh_terms: D000328:Adult; D015331:Cohort Studies; D005260:Female; D006085:Graft Survival; D006684:HLA-DR Antigens; D015395:Histocompatibility Antigens Class I; D006801:Humans; D016030:Kidney Transplantation; D019520:Living Donors; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D014181:Transplantation Immunology
chemical_list: D006684:HLA-DR Antigens; D015395:Histocompatibility Antigens Class I
keywords: human leukocyte antigen; kidney; living donor; mismatch; paired donation; transplant