Balancing Benefits and Risks: A Systematic Review and Meta-Analysis of ABO-Incompatible Kidney Transplantation

To update and expand clinical evidence comparing allograft and recipient survival as well as perioperative complications between ABO-incompatible and center-matched or concurrent ABO-compatible kidney transplant recipients.

Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines, PubMed, Scopus, and Embase were searched from 2010 through December 2024 using prespecified Medical Subject Headings (MeSH) terms. Observational cohort and registry studies reporting patient survival, graft survival, or rejection episodes were included. Initial screening was restricted to English-language publications. Methodological quality was appraised via the Newcastle-Ottawa Scale. Random-effects and fixed-effects models were applied to calculate pooled risk ratios with 95% confidence intervals. Meta-regression, publication bias assessments, and confounding evaluations were allocated to supplementary files owing to data sparsity across unadjusted subsets.

Data from 63 observational studies (5,852 ABO-incompatible and 47,950 ABO-compatible recipients) were synthesized. ABO-incompatible transplantation was associated with higher risks of overall rejection (risk ratio = 1.28, 95% confidence interval: 1.17-1.40) and antibody-mediated rejection (risk ratio = 2.14, 95% confidence interval: 1.48-3.09), whereas T-cell-mediated rejection showed comparable intervals (risk ratio = 0.86, 95% confidence interval: 0.72-1.04). Short- and long-term patient and graft survival estimates (at 1, 3, and 10 years) demonstrated wide compatibility between cohorts. However, 5-year patient survival showed lower compatibility with the null, favoring ABO-compatible transplants (risk ratio = 1.62, 95% confidence interval: 1.13-2.32). Surgical complications and postoperative bleeding were markedly higher in ABO-incompatible recipients.

ABO-incompatible kidney transplantation provides valuable expanded organ access with comparable 1-, 3-, and 10-year survival estimates, but carries elevated risks of rejection, early bleeding, and infections, alongside a noted divergence in 5-year patient survival.