Long-term renal function and complication profiles after ABO-incompatible vs compatible living-donor kidney...

ABO-incompatible (ABOi) kidney transplantation expands the living-donor pool but may increase immunologic and infectious risks. Advances in desensitization have improved outcomes, yet long-term comparative data remain limited. We hypothesized that ABOi living-donor kidney transplantation achieves renal function and complication rates comparable to ABO-compatible (ABOc) procedures under modern protocols.

To assess whether long-term renal function and complication profiles remain comparable between ABOi and ABOc living-donor kidney transplant recipients.

A retrospective single-center cohort study was conducted in a Portuguese transplant program, including all adult living-donor kidney transplants from January 2014 to December 2022 (follow-up to June 2023). A total of 208 recipients were included: 22 ABOi and 186 ABOc, excluding human leukocyte antigen-incompatible or high immunologic risk cases. Continuous variables were compared using Mann-Whitney U or t-tests and categorical variables with Fisher's exact test. Longitudinal changes were assessed by the Friedman test. Survival was analyzed with Kaplan-Meier and log-rank tests, with graft survival death-censored. Missing data were handled by available-case analysis.

Median follow-up was 57 months. Five-year patient survival was 92.9% [95% confidence interval (CI): 79.4-100] in ABOi and 90.3% (95%CI: 85.5-95.2) in ABOc (P = 0.81). Graft survival was also comparable. Estimated glomerular filtration rate trajectories and proteinuria did not differ significantly between groups. Rates of rejection, infections, and surgical or hemorrhagic complications were similar. No significant differences were found after adjustment.

ABOi transplantation achieved outcomes comparable to ABOc living-donor transplantation under contemporary desensitization protocols. These findings support the safety and efficacy of ABOi transplantation, while ongoing multicenter follow-up is needed to confirm long-term safety.