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MOST HLA-MATCHED KIDNEY TRANSPLANTS OCCUR SOON AFTER LISTING, LEAVING A WAITING LIST OF PATIENTS WITH INCREASINGLY UNCOMMON HLA TYPES.
J. Michael Cecka, PhD, David W. Gjertson and Erik B. Edwards. Los Angeles CA, USA, University of California, Los Angeles, 90095-1652, UCLA Immunogenetics Center and Richmond VA, USA, United Network for Organ Sharing.

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About 16% of deceased donor kidneys each year are transplanted to HLA-matched recipients in the US. Although we might expect an increase in HLA-matched transplants as the waiting list grows, the percentage of patients who received a matched transplant remained steady from 1996-2003. We examined the dynamics of HLA-matched kidney transplantation and HLA phenotypes on the waitng list.
We analyzed waiting times for recipients of zero HLA-mismatched deceased donor kidneys shared under UNOS between 1996-1999. We assessed the changing distribution of HLA phenotypes over time among patients who entered the waiting list in 1997 by determining the number who were HLA-matched with at least one donor from 1997, then repeating the analysis for those listed in 1997 who were still waiting in 1998 against 1998 donors and so on for up to 5 years.
75% of the HLA-matched transplants occurred within 18 months of listing. Among 18,847 patients first listed in 1997, 37% were HLA-matched with at least one donor in 1997. Of the 2,852 who remained on the list in 2002, only 19% were HLA-matched with at least one donor in 2002. The same experiment using patients first listed in 1996 yielded similar results. Finally, only 28% of those patients who were HLA-matched with >10 donors in 1997 received an HLA-matched transplant.
We demonstrated that 75% of HLA-matched transplants occured within 18 months after listing and that patients with common HLA phenotypes were depleted from the waiting pool leaving patients who are less likely to receive an HLA-matched graft.