Patient and Graft Survival After A1/A2-incompatible Living Donor Kidney Transplantation

Abstract

ABO type B and O kidney transplant candidates have increased difficulty identifying a compatible donor for living donor kidney transplantation (LDKT) and are harder to match in kidney paired donation registries. A2-incompatible (A2i) LDKT increases access to LDKT for these patients. To better inform living donor selection, we evaluated the association between A2i LDKT and patient and graft survival.

Methods: We used weighted Cox regression to compare mortality, death-censored graft failure, and all-cause graft loss in A2i versus ABO-compatible (ABOc) recipients.

Results: Using Scientific Registry of Transplant Recipients data 2000-2019, we identified 345 A2i LDKT recipients. Mortality was comparable among A2i and ABOc recipients; weighted 1-/5-/10-y mortality was 0.9%/6.5%/24.2%, respectively, among A2i LDKT recipients versus 1.4%/7.7%/22.2%, respectively, among ABOc LDKT recipients (weighted hazard ratio [wHR], _0.811.04_1.33; P = 0.8). However, A2i recipients faced higher risk of death-censored graft failure; weighted 1-/5-/10-y graft failure was 5.7%/11.6%/22.4% for A2i versus 1.7%/7.5%/17.2% for ABOc recipients (wHR in year 1 = _2.243.56_5.66; through year 5 = _1.251.78_2.53; through year 10 = _1.151.55_2.07). By comparison, 1-/5-/10-y wHRs for A1-incompatible recipients were _0.631.96_6.08/_0.390.94_2.27/_0.390.83_1.74.

Conclusions: A2i LDKT is generally safe, but A2i donor/recipient pairs should be counseled about the increased risk of graft failure and be monitored as closely as their A1-incompatible counterparts posttransplant.