PubMed Health⌕ Search

Biomedical subjects

T Wujciak

Publications and source records attributed to T Wujciak.

13 recordsLinked to original sources
PubMed1994

The influence of HLA compatibility on graft survival after heart transplantation. The Collaborative Transplant Study.

BACKGROUND: In cardiac transplantation, it is standard practice for donor hearts to be allocated to recipients without consideration of the extent of HLA matching. Because the HLA system is highly polymorphic, the likelihood that donor hearts will be well matched to their recipients by chance alone is extremely small. It has therefore not been possible in the past to analyze adequately the success rate of transplantation with HLA-matched hearts. METHODS: We initiated a collaborative study in 1985 to evaluate the influence of HLA compatibility on graft survival in heart transplantation. Data were collected from 104 centers in 24 countries. RESULTS: Of the 8331 patients, 128 received a graft with no HLA-A, B, or DR mismatches or only one mismatch. This frequency (1.5 percent) corresponds to the rate that would be expected from a random allocation of donor organs. The three-year rate of graft survival correlated strongly with HLA compatibility, decreasing from a mean (+/- SE) of 83 +/- 4 percent for the 128 donor hearts with no mismatches or only one mismatch to 76 +/- 2 percent for the 439 hearts with two mismatches and 71 +/- 1 percent for the 7764 hearts with three to six mismatches (P < 0.001). Multifactorial Cox regression analysis showed that this effect was independent of the age and sex of the donor and recipient, the type of underlying disease, the duration of cold ischemia, and the use of prophylaxis with antilymphocyte antibodies (P = 0.005). CONCLUSIONS: Graft survival in heart transplantation is significantly influenced by the extent of HLA compatibility.

Adolescent↗
PubMed1994

[Effect of HLA compatibility on kidney transplantation].

The influence of the HLA system on the success rate of kidney transplantations was evaluated in a worldwide collaborative study. The results confirm the influence of the HLA chromosome on transplants from related donors. Moreover, a highly significant effect of compatibility for the HLA-A, -B, -DR antigens was observed in cadaver transplants (p < 0.0001). The great importance of a good quality of tissue typing was emphasized by a) the observation that a significant influence of compatibility for the HLA-A, -B antigens was evident only if donors and recipients were typed for 'split' specificities and not when they were typed for 'broad' antigens, and b) an improved effect of HLA-DR compatibility when serological typing errors were corrected by molecular (DNA) typing. Computations show that kidney allocation according to the best possible HLA compatibility results in a gain of 800 transplant function years per 1,000 transplantations over a 10-year period.

Cadaver↗
PubMed1993

A proposal for improved cadaver kidney allocation.

The allocation of cadaver kidneys for transplantation should have two objectives: a fair distribution of kidneys among the waiting recipients and a high success rate. Currently, organ exchange organizations are following mainly a policy of success oriented allocation in that the kidneys are distributed according to the best achievable HLA match. A consequence of this policy is that patients with rare HLA phenotypes experience prolonged waiting times and that there are large kidney exchange imbalances among transplant centers. Based on theoretical considerations, we described previously the selection routine COMB which was aimed at decreasing excessive waiting times. In this study we present an extension of this routine called XCOMB which builds on realistic conditions according to the current Euro-transplant waiting list. This new procedure decreases the average and maximum waiting time, adjusts for rare HLA phenotypes and HLA homozygosity, provides for a reasonably balanced kidney exchange rate among centers, and guarantees an HLA match distribution and overall transplant success rate near the theoretically possible optimum. The program was tested in an extensive simulation based on actual data derived from 35,000 cadaver kidney transplants. Although more complex than procedures currently in use, the program's efficient software allows the selection of a patient within one second from a waiting list of 10,000 potential recipients, using readily available computer hardware.

Algorithms↗
PubMed1993

Computer analysis of cadaver kidney allocation procedures.

Data of 32,000 donors were utilized for a computer simulation to analyze the effect of selection parameters on the outcome of kidney transplants. If the HLA match grade is considered for organ allocation, the overall 1-year graft survival rate is up to 7% higher for first cadaver transplants and up to 12% higher for second transplants than if HLA matching is disregarded. This solely success-oriented organ allocation method, however, leads to prolonged waiting times for patients with rare HLA phenotypes. We developed a selection procedure that yields results near the theoretical optimum: 95% of all patients can be transplanted with 0-2 HLA-A, -B, -DR antigen mismatches, the average waiting time decreases to 20 months, and no patient needs to wait longer for a transplant than 6 years. The overall graft survival rate is only 0.4% lower than the rate obtainable with strictly HLA-oriented allocation. The method prevents "poorly matchable" patients from accumulating on the waiting list. Additionally, the unfavorable race ratio in the North American recipient pool can be largely normalized.

Cadaver↗
PubMed1992

Current status of HLA matching in renal transplantation. The Collaborative Transplant Study.

The impact of HLA compatibility on the success rate of kidney transplants was studied in over 80,000 recipients of primary transplants. The transplants were done from 1982 to 1991 at over 300 transplant centers in 43 countries. The results show that matching the HLA chromosomes in related donor transplants has a striking influence. It is also important that matching for individual HLA antigens in cadaver transplants provides a highly significant improvement in graft survival (P less than 0.0001). After 5 years, matched grafts have a survival rate approximately 20% higher than completely mismatched grafts. The matching effect is particularly strong in presensitized and second graft recipients. There is now direct evidence that even if it is necessary to transport well-matched kidneys a long way, they have a significantly higher success rate than locally transplanted poorly matched kidneys. New data based on molecular technology show that the precise identification of HLA-DR antigens by DNA typing further improves the success rate of HLA-matched transplants.

Follow-Up Studies↗