Outcomes of ABO-Incompatible kidney transplantation with respect to baseline isoagglutinin immunoglobulin G titers: A retrospective observational study

Abstract

Background: ABO-incompatible kidney transplantation is one of the ways to increase the donor pool by as much as 30%–35%. Studies comparing baseline titers have shown conflicting results with respect to graft outcomes. This study attempts to evaluate the outcomes of ABO-incompatible transplant with high and low baseline immunoglobulin G (IgG) isoagglutinin titers to the outcomes of ABO compatible transplant. Materials and Methods: This was a retrospective observational study, in which 954 renal transplant recipients were included in the study. Of these, 873 patients had undergone ABO compatible kidney transplantation. Of the 81 patients who underwent an ABO-incompatible transplantation, 67 belonged to the low titer group (defined as the baseline IgG ≤ 1:64) and 14 belonged to the high titer group (defined as baseline IgG ≥ 1:128). Patients were followed up for a period of 1 year. Laboratory assessments were performed at baseline and at each visit. Graft survival, rejection episodes, patient survival, and infections were assessed on a continuous basis. Graft loss was defined by the need to return to dialysis. Results: Death censored graft survival was 92.3% in the high titer group as compared to 98.2% in ABO compatible group, but this difference was not significant (P = 0.231). Graft survival in the low titer group (96.8%) was comparable to the compatible group (P = 0.328). The proportion of patients who developed biopsy-proven rejections was lower in ABO compatible groups (6.5%) when compared to ABOi high (21.4%) and low titer groups (13.4%), respectively (P = 0.063 and 0.033, respectively). Antibody-mediated rejections were significantly fewer in ABO compatible group (1.8%) versus high titer group (21.4%) and low titer group (11.9%) (P = 0.003 and P < 0.001, respectively). Patient survival was higher in ABOc group (97.9%) as compared to high (92.9%) and low titer (94.0%) groups though the difference did not achieve statistical significance. Most of the deaths were attributed to infections. Conclusion: ABO-incompatible transplantation is an acceptable treatment for those with end-stage renal disease; however, this comes with a caveat of increased risk of acute rejections and infections in patients with baseline titers of 1:128 or higher.

Keywords

• abo-incompatible
• graft survival
• hemagglutinin titers
• isoagglutinin titers
• kidney transplantation