Background and objectives ABO blood group–incompatible kidney transplantation is considered a safe procedure, with noninferior outcomes in large cohort studies. Its contribution to living kidney transplantation programs is substantial and growing. Outcomes compared with center-matched ABO blood group–compatible control patients have not been ascertained. Design, setting, participants, & measurements Comprehensive searches were conducted in Embase, Medline, Cochrane, Web-of-Science, and Google Scholar. Meta-analyses Of Observational Studies in Epidemiology study guidelines for observational studies and Newcastle Ottawa bias scale were implemented to assess studies. Meta-analysis was performed using Review Manager 5.3. A subgroup analysis on antibody removal technique was performed. Results After identifying 2728 studies addressing ABO-incompatible kidney transplantation, 26 studies were included, describing 1346 unique patients who were ABO-incompatible and 4943 ABO-compatible controls. Risk of bias was low (all studies ≥7 of 9 stars). Baseline patient characteristics revealed no significant differences in immunologic risk parameters. Statistical heterogeneity of studies was low (I2 0% for graft and patient survival). One-year uncensored graft survival of patients who were ABO-incompatible was 96% versus 98% in ABO compatible controls (relative risk, 0.97; 95% confidence interval, 0.96 to 0.98; P<0.001). Forty-nine percent of reported causes of death in patients who were ABO-incompatible were of infectious origin, versus only 13% in patients who were ABO-compatible (P=0.02). Antibody-mediated rejection (3.86; 95%confidence interval, 2.05 to 7.29; P<0.001), severe nonviral infection (1.44; 95%confidence interval, 1.13 to 1.82; P=0.003), and bleeding (1.92; 95%confidence interval, 1.36 to 2.72; P<0.001) were also more common after ABO-incompatible transplantation. Conclusions ABO-incompatible kidney transplant recipients have good outcomes, albeit inferior to center matched ABO-compatible control patients.

ABO Blood-group system, Acute rejection, Antibodies, Bias, Blood Group Incompatibility, Cause of Death, Cohort Studies, Graft Survival, Humans, Kidney transplantation, Transplant outcomes,
Clinical Journal of the American Society of Nephrology

de Weerd, A.E, & Betjes, M.G.H. (2018). ABO-incompatible kidney transplant outcomes: A meta-analysis. Clinical Journal of the American Society of Nephrology, 13(8), 1234–1243. doi:10.2215/CJN.00540118