Effect of changing the priority for HLA matching on the rates and outcomes of kidney transplantation in minority groups.

BACKGROUND: HLA typing and the time a patient has spent on the waiting list are the primary criteria used to allocate cadaveric kidneys for transplantation in the United States. Candidates with no HLA-A, B, and DR mismatches are given top priority, followed by candidates with the fewest mismatches at the HLA-B and DR loci; this policy contributes to a higher transplantation rate among whites than nonwhites. We hypothesized that changing this allocation policy would affect graft survival and the racial balance among transplant recipients. METHODS: We estimated the relative rates of kidney transplantation according to race resulting from the current allocation policy and racial differences in HLA antigen profiles, using a Cox model for the time from placement on the waiting list to transplantation. Another model, also adjusted for HLA-B and DR antigen profiles, estimated the relative rates of kidney transplantation that would result if the distribution of these antigen profiles were identical among the racial and ethnic groups. We also investigated the effect of HLA matching on the risk of graft failure, using a Cox model for the time from the first transplantation to graft failure. The results of the two analyses were used to estimate the change in the racial balance of transplantation and graft-failure rates that would result from the elimination of HLA-B matching or HLA-B and DR matching as a means of assigning priority. RESULTS: Eliminating the HLA-B matching as a priority while maintaining HLA-DR matching as a priority would decrease the number of transplantations among whites by 4.0 percent (166 fewer transplantations over a one-year period), whereas it would increase the number among nonwhites by 6.3 percent and increase the rate of graft loss by 2.0 percent. CONCLUSIONS: Removing HLA-B matching as a priority for the allocation of cadaveric kidneys could reduce the existing racial imbalance by increasing the number of transplantations among nonwhites, with only a small increase in the rate of graft loss.

Preemptive transplantation for patients with diabetes-related kidney disease.

BACKGROUND: Preemptive kidney transplantation (PreKT) before initiation of chronic dialysis has been examined recently with favorable results as the most effective treatment for kidney failure. Given that few of these studies are disease specific, the present analyses investigated the outcomes of PreKT by transplantation option and diabetes type. METHODS: The impact of PreKT on posttransplantation mortality and graft failure was examined in 23 238 adults with type 1 and type 2 diabetes mellitus (DM), receiving either living or deceased donor kidneys or undergoing simultaneous pancreas-kidney (SPK) transplantation between January 1, 1997, and December 31, 2002. RESULTS: The PreKTs were provided to 14.4% of patients with type 1 DM and 6.7% of patients with type 2 DM. Cox regression models were used to estimate the effect of PreKT on the adjusted risk ratio (RR) of graft failure and mortality. After adjusting for multiple factors, PreKT in this era was associated with lower RR of mortality only among type 1 and type 2 diabetic recipients of transplants from living donors and SPK transplant recipients with type 1 DM (RR, 0.50-0.65; P<.007 for each). The effect on graft failure was less pronounced, significant only for preemptive SPK transplant recipients (RR, 0.79; P=.01 vs nonpreemptive SPK transplant recipients). CONCLUSIONS: These analyses suggest that PreKT has significant benefits for subsets of patients with types 1 and 2 DM and end-stage renal disease. It also suggests a time trend toward less benefit from preemptive transplants from deceased donors in more recent years compared with the early 1990s. This observation and the discrepancies between RR of graft loss and RR of mortality deserve further study.

Predicted lifetimes for adult and pediatric split liver versus adult whole liver transplant recipients.

Split liver transplantation allows 2 recipients to receive transplants from one organ. Comparisons of predicted lifetimes for two alternatives (split liver for an adult and pediatric recipient vs. whole liver for an adult recipient) can help guide the use of donor livers. We analyzed mortality risk for 48,888 waitlisted candidates, 907 split and 21,913 whole deceased donor liver transplant recipients between January 1, 1995 and February 26, 2002. Cox regression models for pediatric and adult patients assessed average relative wait list and post-transplant death risks, for split liver recipients. Life years gained compared with remaining on the waiting list over a 2-year period were calculated. Seventy-six splits (152 recipients) and 24 re-transplants resulted from every 100 livers (13.1% [adult] and 18.0% [pediatric] 2-year re-transplant rates, respectively). Whole livers used for 93 adults also utilized 100 livers (re-transplant rate 7.0%). Eleven extra life years and 59 incremental recipients accrued from each 100 livers used for split compared with whole organ transplants. Split liver transplantation could provide enough organs to satisfy the entire current demand for pediatric donor livers in the United States, provide more aggregate years of life than whole organ transplants and result in larger numbers of recipients.

Liver and intestine transplantation.

The most significant development in liver transplantation in the USA over the past year was the full implementation of the MELD- and PELD-based allocation policy in March 2002, which shifted emphasis from waiting time within broad medical urgency status to prioritization by risk of waiting list death. The implementation of this system has led to a decrease in pretransplant mortality without increasing post-transplant mortality, despite a higher severity of illness at the time of transplant. The trend over the last few years of rapidly increasing numbers of adult living donor liver transplants was reversed in 2002 by a decline of more than 30% in the number of these procedures. In 2002, a greater percentage of women received livers from living donors (43%) than deceased donors (34%), possibly because of size considerations. From 1993 to 2001, the waiting list increased more than sixfold, from 2902 patients to 18,047 patients. For the first time since 1993, the waiting list size decreased in 2002, dropping 6% to 16,974 candidates. The percentage of temporarily inactive liver candidates also increased from 2001, thus the net decrease in the active waiting list for 2002 was 12%. This may reflect a trend toward less pre-emptive listing practices under MELD. Intestine transplantation remains a low-volume procedure limited to a few transplant centers and is still accompanied by significant pre- and post-transplantation risks. As this procedure matures, its application may increase to include recipients at an earlier stage of their disease with better likelihood of success.