#5-OR
THE EFFECTIVENESS OF USING ANTIBODY INDUCTION ACCORDING TO THE DEGREE OF HLA MISMATCHES.
S. Bunnapradist and S. K. Takemoto. Los Angeles CA, USA, Cedars Sinai Multiorgan Transplant Program and Los Angeles CA, USA, UCLA Immunogenetics Center.
Aims: Antibody preparation is commonly used as induction therapy in kidney transplantation. HLA mismatches have a strong impact on acute rejection rate (AR) and renal allograft survival (GS). The objective of this study was to evaluate the effectiveness of antibody induction according to the degree of HLA mismatches.
Methods: We examined data reported to the United Network for Organ Sharing (UNOS) including 24,901 deceased and 12,859 living donor recipients transplanted between 1999 and 2001. Fifty-one percent of deceased (DD) and 45% of living donor (LD) recipients received induction therapy. Propensity scores (PS) were calculated to indicate patient, donor and transplant factors associated with use of induction. Levels of HLA match examined for deceased donor recipients were 0 ABDR (n=3,239), 0 DR (n=4,210) with A and/or B locus mismatches, and DR mismatched transplants (n=12,980), and 0 (n=1,133), 1 (n=3,836) and 2 (n=7,890) haplotype mismatches for living donor recipients. Outcome parameters included unadjusted graft survival, hazard ratio for graft loss and odds ratio for first-year acute rejection.
Results: Recipients with DR mismatches more likely received induction antibody for both deceased (PS=1.11, 95% CI 1.04-1.19, vs. 0 DR mismatch) and living donors (1.36, 1.22-1.52). Induction antibody reduced the risk of acute rejection for deceased donor recipients regardless of level of HLA match (30% in 0 ABDR MM, 24% in 0 DR mismatch and 31% in DR mismatched transplants), and for 2 haplotype mismatched living donor recipients (18%); in other living donor recipients, reductions in acute rejection rates were observed but not statistically significant. Relative risk of acute rejection and graft survival of those receiving induction vs. no induction by level of HLA mismatch are shown for deceased and living donor in the figure below. Induction reduced the risk of graft loss only for DR mismatched deceased donor recipients (11%). The incidence of adverse events associated with antibody preparations was not evaluated in this study but has been shown to differ significantly between IL-2R and lymphocyte-depleting antibodies and should be taken into account in treatment decisions.
Conclusions: The use of antibody induction significantly reduced the odds of rejection for all levels of matches in deceased donor transplants and for 2 haplotype mismatched living donor transplants. Induction had an impact on graft survival in DR mismatched deceased donor transplants.