PHILADELPHIA – Eliminating HLA-B matching from the U.S. priority-points formula that was used for allocating deceased-donor kidneys partially eliminated the allocation disparity against black recipients, but a residual disparity remained, based on an analysis of more than 57,000 U.S. kidney transplants during 2000-2009.
Removal of HLA-B matching from the allocation criteria cut the amount of disparity in organs received by black patients, compared with white patients, by a relative 23%, but during 2006-2009 blacks received deceased-donor kidneys at a rate that was 19% below the rate of kidneys that went to white patients, Dr. Erin C. Hall said at the American Transplant Congress, which was sponsored by the American Society of Transplant Surgeons.
In May 2003, the U.S. Organ Procurement and Transplantation Network – the deceased-donor organ distribution network established by the federal government and administered by the United Network for Organ Sharing (UNOS) – eliminated HLA-B matching as an allocation criterion.
Factors that may explain the residual disparity remain unidentified. Future studies could focus on an examination of center-by-center allocation differences by race in an effort to identify other sources for the disparity, said Dr. Hall, a researcher in the transplant surgery division at Johns Hopkins Hospital in Baltimore.
Before May 2003, U.S. kidney allocation procedures gave priority to recipients who matched for more of the six HLA loci, a policy that improved transplantation outcomes but decreased the number of nonwhite recipients who received organs (N. Engl. J. Med. 2004;350:545-51).
To investigate the impact of this change, Dr. Hall and her associated reviewed UNOS records for the 12,956 kidney transplants that were done during 2000–May 2003 using deceased-donor organs, and for the 44,704 transplants done during May 2003–2009. During the two periods, the level of black patients who were registered with UNOS to await kidney transplants held very steady, accounting for 44% all of listed patients before the criterion change, and for 45% after the change.
During 2000-2003, black patients received deceased-donor kidney transplants at 38% below the rate of white patients, according to a multivariate analysis that adjusted for patient differences in age, sex, primary renal disease cause, dialysis modality, use of preemptive transplant, insurance status, education, panel-reactive antibody level over time, and blood type. During 2003-2009, the transplantation rate among black patients was 23% less than it was in white patients. To allow for equilibration in transplant rates following the 2003 criterion change, Dr. Hall also analyzed transplantation rates during 2006-2009. During this period, the rate in black patients lagged 19% behind the rate in white patients, she reported. All three between-group differences were statistically significant. The amount of change between the 38% disparity rate during 2000-2003 and the 23% disparity rate during 2003-2009 constituted a 23% relative decline in the disparity rate.
Dr. Hall said that she had no relevant financial disclosures.