Long-Term Clinical Outcomes of ABO-Incompatible Kidney Transplantation in Patients With High Baseline Anti-A/B Antibody Titers

Background: This study aimed to investigate the long-term clinical outcomes of ABO-incompatible kidney transplantation (ABO icKT) in patients with high baseline anti-A/B antibody titers. Methods: This study included 271 cases of ABO icKT. Of these, 42 patients with a baseline antibody titer of ≥ 1:256 were assigned to the high-titer group, while the remaining 229 patients were categorized into the low-titer group. We compared the groups regarding the number of required pre-transplant plasmapheresis (PP) and intravenous immunoglobulin (IVIG) sessions. Clinical outcomes included post-operative bleeding, biopsy-proven acute rejection (BPAR), infectious complications, changes in allograft function, and long-term allograft and patient survival. Results: The high-titer group required significantly more sessions of PP and IVIG than the low-titer group (8.74 ± 2.68 vs. 3.85 ± 1.64; P < 0.001). Following transplantation, anti-A/B antibody titers remained elevated in the high-titer group. There was no significant difference in post-operative bleeding between the two groups. However, the incidence of bacterial infection was higher in the high-titer group compared with the low-titer group (47.62% vs. 30.57%; P = 0.031), although this association was not significant in multivariable analysis. The incidence of total BPAR did not differ significantly; however, chronic active antibody-mediated rejection was more frequently observed in the high-titer group (7.14% vs. 0.87%; P = 0.028). Overall allograft and patient survival did not differ significantly between the two groups. Conclusion: Patients with high baseline anti-A/B titers demonstrated comparable short-term and long-term patient and allograft outcomes to those in the low-titer group.