Baseline Donor‐Specific Antibody Levels and Outcomes in Positive Crossmatch Kidney Transplantation

Renal transplant candidates with donor‐specific alloantibody (DSA) have increased risk of antibody‐mediated allograft injury. The goal of this study was to correlate the risk of antibody‐mediated rejection (AMR), transplant glomerulopathy (TG) and graft survival with the baseline DSA level (prior to initiation of pretransplant conditioning). These analyses include 119 positive crossmatch (+XM) compared to 70 negative crossmatch (?XM) transplants performed between April 2000 and July 2007. Using a combination of cell‐based crossmatch tests, DSA level was stratified into very high +XM, high +XM, low +XM and ?XM groups. In +XM transplants, increasing DSA level was associated with increased risk for AMR (HR = 1.76 [1.51, 2.07], p = 0.0001) but not TG (p = 0.18). We found an increased risk for both early and late allograft loss associated with very high DSA (HR = 7.71 [2.95, 20.1], p = 0.0001). Although lower DSA recipients commonly developed AMR and TG, allograft survival was similar to that of ?XM patients (p = 0.31). We conclude that the baseline DSA level correlates with risk of early and late alloantibody‐mediated allograft injury. With current protocols, very high baseline DSA patients have high rates of AMR and poor long‐term allograft survival highlighting the need for improved therapy for these candidates.