The PROCARE consortium: Toward an improved allocation strategy for kidney allografts

Kidney transplantation is the best treatment option for patients with end-stage renal failure. At present, approximately 800 Dutch patients are registered on the active waiting list of Eurotransplant. The waiting time in the Netherlands for a kidney from a deceased donor is on average between 3 and 4 years. During this period, patients are fully dependent on dialysis, which replaces only partly the renal function, whereas the quality of life is limited. Mortality among patients on the waiting list is high. In order to increase the number of kidney donors, several initiatives have been undertaken by the Dutch Kidney Foundation including national calls for donor registration and providing information on organ donation and kidney transplantation. The aim of the national PROCARE consortium is to develop improved matching algorithms that will lead to a prolonged survival of transplanted donor kidneys and a reduced HLA immunization. The latter will positively affect the waiting time for a retransplantation.The present algorithm for allocation is among others based on matching for HLA antigens, which were originally defined by antibodies using serological typing techniques. However, several studies suggest that this algorithm needs adaptation and that other immune parameters which are currently not included may assist in improving graft survival rates. We will employ a multicenter-based evaluation on 5429 patients transplanted between 1995 and 2005 in the Netherlands. The association between key clinical endpoints and selected laboratory defined parameters will be examined, including Luminex-defined HLA antibody specificities, T and B cell epitopes recognized on the mismatched HLA antigens, non-HLA antibodies, and also polymorphisms in complement and Fc receptors functionally associated with effector functions of anti-graft antibodies. From these data, key parameters determining the success of kidney transplantation will be identified which will lead to the identification of additional parameters to be included in future matching algorithms aiming to extend survival of transplanted kidneys and to diminish HLA immunization. Computer simulation studies will reveal the number of patients having a direct benefit from improved matching, the effect on shortening of the waiting list, and the decrease in waiting time.     

A new allocation plan for renal transplantation

BACKGROUND: A novel plan of renal allograft allocation has been conducted by United Network for Organ Sharing Region 1 transplant centers since September 3, 1996, based upon HLA matching, time waiting, and population distance points. The objectives of this plan were to achieve a balance between increasing the opportunity of renal transplantation for those patients listed with long waiting times and promoting local organ donor availability. METHODS: A single list of candidates was formulated for each cadaver donor, assigning a maximum of 8 points for time waiting, a maximum of 8 points for population distance from the donor hospital, and HLA points based upon the degree of B/DR mismatch. Additional points were awarded to a cross-match-negative patient with a panel-reactive antibody of >80%, and to pediatric patients. RESULTS: The total number of kidneys transplanted to patients who had waited >3 years was 100 (46%), and to patients who had waited >2.5-3 years was 29 (13%). However, the total number of kidneys transplanted to patients with the maximum population distance points was only 72 (33%). Thus, although the plan achieved a favorable distribution of kidneys to patients with longer waiting times (nearly 60%), the other, equally important objective of promoting local donor availability was not initially accomplished. Moreover, minor HLA B/DR differences between the donor and the recipient (i.e., not phenotypically matched) were unexpectedly consequential in determining allocation. As a result of these observations, the following adjustments were made in the plan (as of December 3, 1997): a maximum of 10 points for population distance, a maximum of 8 points for time waiting (both by a linear correlation), and the retention of HLA points for 0 B/DR mismatch only. After these interval changes, the percentage of patients receiving a kidney with some population distance points increased from 85% to 96%. Conclusions. We have shown that a heterogeneous region of multiple transplant centers can devise (and modify) an innovative and balanced plan that provides an equitable system of allocation for an ever-increasing number of patients.     

Balancing organ quality, HLA-matching, and waiting times: impact of a pediatric priority allocation policy for deceased donor kidneys in Quebec

Deceased donor kidney allocation policy must balance the desire for high-quality organs, good human leukocyte antigen (HLA) matching, and minimal waiting times. We describe a 10-fold reduction in waiting times and an improvement in nonimmunologic indices of organ quality for child recipients after a change in organ allocation policy in Quebec, Canada. The new policy gives first priority to children (<18 yr) irrespective of HLA matching or waiting time. HLA matching after the policy change was predictably much worse. This study highlights the trade-offs that must be considered both in setting allocation policy and in decisions for individual recipients. We also consider potential unintended negative effects of such a policy change.     

The national impact of the 1995 changes to the UNOS renal allocation system

In 1995, changes in the United Network for Organ Sharing (UNOS) renal allocation policies expanded the mandatory share (MS) category to include zero antigen mismatches (0 mm), increased points for waiting time and for pediatric status, and eliminated points for certain HLA match grades. Data from the national scientific registry on 11344 and 11652 renal allograft recipients were analyzed for periods prior to and following the policy changes to assess the impact on organ allocation. The overall frequency of transplants going to non-Caucasians increased between the study periods, but the increase was significant only in the MS category. The proportion of MS transplants nearly doubled for African-Americans, increasing from 5.5% to 10.5%, while Hispanic/Latino recipients experienced a smaller increase, from 7.2% to 8.9%. The increased numbers of MS transplants clearly resulted from the inclusion of the 0 mm in the MS category. Among the NMS transplants, the average number of mismatched HLA antigens increased slightly. No effect of the additional points for waiting time was observed among recipients of non-mandatory share (NMS) transplants. The increase in mean waiting time until transplant for NMS recipients was attributable to the growth in the size of the waiting list. In contrast, there was a significant increase in mean waiting time for MS recipients. There were no significant changes in the proportions of sensitized or pediatric recipients between the study periods. In conclusion, only the changes in the MS policies appeared to have any significant effect on renal allocation. Further efforts will be required to address increasing allocation to patients disadvantaged by sensitization and/or prolonged waiting times.     

It takes six to boogie: allocating cadaver kidneys in Eurotransplant

In March 1996, a new allocation point system for cadaver kidneys, the Eurotransplant (ET) Kidney Allocation System (KAS), was introduced in ET, the first multinational organ exchange organization. The aims of ETKAS were to reduce average and maximum waiting time, to allow patients with rare human leukocyte antigen (HLA) phenotypes or combinations to receive an "optimal" offer, to keep the exchange rates between the participating countries balanced, and finally to keep optimal graft survival, by means of HLA matching. Elderly patients and highly sensitized patients profit in addition from special programs, the ET Senior Program and the Acceptable Mismatch Program, respectively. All kidneys are offered to the pool and are allocated according to the degree of HLA matching, mismatch probability, waiting time, distance from the donor center, and balance between the countries participating in ET. A summary of 6 years' experience with the ETKAS is presented in this article.     

Human leukocyte antigen in the allocation of kidneys from cadaveric donors in the United States

Minorities wait longer for a cadaveric donor kidney transplant than whites. For example, the median waiting time to transplant for candidates listed from 1997 to 1998 was 874 days for whites, 1,493 days for blacks, 1,281 days for Hispanics, 1,491 days for Asians, and 1,466 days for others. The current allocation algorithm has been criticized as contributing to decreased access to transplants for racial minorities. There are two levels in the current algorithm: The first is mandatory national sharing between donors and patients with zero human leukocyte antigen (HLA)-A, B, and DR mismatches. The second occurs if there are no candidates and local placement is accomplished based on an algorithm with an HLA component that assigns seven, five, and two points to zero, one, and two HLA-B and DR mismatches, respectively. An analysis of the data shows that a higher percentage of white recipients (21%) received zero antigen mismatched kidneys compared with other races: blacks (7%), Hispanics (14%), and Asians (7%). Whites also received the highest percentage of kidneys with zero B and DR mismatches and one B and DR mismatch compared with the other races. These data indicate that the current algorithm favors whites over minorities, and it is most likely that giving points for HLA-B matching is a strong contributory factor. To address this inequity, the Organ Procurement and Transplantation Network and United Network for Organ Sharing Board of Directors approved a recommendation in November 2002 to change the HLA points to award two points for zero DR mismatches and one point for one DR mismatch. Obviously it will take some time to gather sufficient data to allow meaningful analysis of the effect of the policy change.     

Access to kidney transplantation in France of non-French patients and French patients living in overseas territories

BACKGROUND: In France, foreign patients, whether resident or not in France, can register on the national waiting list under certain conditions. We compared waiting time to kidney transplantation, the level of HLA matching and graft cold ischemia time between foreign patients and French patients living in mainland France or in French overseas territories (FOT). METHODS: We performed a retrospective cohort survey using the nationwide registry. Between 1996 and 2003, 18,595 patients were registered on the French waiting list. Of these, 9.9% were of non-French nationality (0.7% Greek, 1.4% Italian, 1.5% other European, 3.7% North African, 1.8% sub-Saharan African and 0.9% other), and 3.8% were French nationals living in FOT. RESULTS: Median waiting time differed significantly between groups, from 13.8 months for mainland French patients to 39.5 months for sub-Saharan African patients. After adjustment for other factors significantly linked to waiting time, French residents of FOT (RR=0.83; P<0.001) and patients from sub-Saharan Africa (RR=0.75; P<0.0001) were found to wait significantly longer than other patients. HLA matching level, particularly HLA-A and HLA-B, was worse for African patients. After adjustment for the transplant team, cold ischemia time was found to be longer for Greeks (30.4 hr, P<0.0001) and French patients living in FOT (33.3 hr, P<0.0001) than for mainland French patients (21.2 hr). CONCLUSIONS.: Programs promoting organ donation aimed at minorities of African origin should improve their access to transplantation in France. We also need to strengthen international cooperation programs in certain countries to assist access to transplantation and to increase graft quality.     

For the many: permitting deceased donor kidney transplantation across low‐titre blood group antibodies can reduce wait times for blood group B recipients,and improve the overall number of 000MM transplants ‐ a multicentre observational cohort study

Blood group O or B recipients wait longer for a kidney transplant. We studied the distribution of anti‐ABO blood group antibody titres in patients awaiting a kidney transplant, and modelled the effect of altering the UK National Kidney Allocation Scheme to allow for patients with ‘LOW’ titres (≤1:8, ≤3 dilutions) to receive a deceased donor ABOi (ddABOi) transplant. In a prospective study of 239 adult patients on the waiting list for a transplant in 2 UK centres, ABO‐antibody titres (anti‐A and anti‐B) were measured. Based on the proportions of ‘LOW’ anti‐A or anti‐B antibodies, four simulations were performed to model the current allocation rules compared with variations allowing ddABOi allocation under various conditions of blood group, HLA matching, and waiting time. The simulations permitting ddABOi resulted in more blood group B recipients being transplanted, with median waiting time reduced for this group of recipients, and more equitable waiting times across blood groups. Additionally, permitting ddABOi resulted in greater numbers of 000MM allocations overall in compatible transplants under modelled conditions. Changing allocation in the UK to permit ddABOi in patients with ‘LOW’ titres would not change the total number of transplants, but redistributes allocation more equitably amongst blood groups, altering waiting times accordingly.     

The Expanded Criteria Donor Policy: An Evaluation of Program Objectives and Indirect Ramifications

The expanded criteria donor (ECD) policy was formalized in 2002, which defined higher-risk deceased donor kidneys recovered for transplantation. There has not been a comprehensive examination of the impact of policy on the allocation of ECD kidneys, waiting times for transplant, center listing patterns or human leukocyte antigen (HLA) matching. We examined transplant candidates from 1998 to 2004 utilizing a national database. We constructed models to assess alterations in recipient characteristics of ECD kidneys and trends in waiting time and cold ischemia time (CIT) associated with policy. We also evaluated the impact of the proportion of center candidate listings for ECD kidneys on waiting times. Elderly recipients were more likely to receive ECDs following policy (odds ratio = 1.36, p < 0.01). There was no association of decreased CIT or pretransplant dialysis time while increasing HLA mismatching with policy inception. Over one quarter of centers listed < 20% of candidates for ECDs, while an additional quarter of centers listed > 90%. Only centers with selective listing for ECDs offered reduced waiting times to ECD recipients. The ECD policy demonstrates potential to achieve certain ascribed goals; however, the full impact of the program, reaching all transplant candidates, may only be achieved once ECD listing patterns are recommended and adopted accordingly.     

A Europe wide acceptable mismatch program will enable transplantation of long waiting highly sensitised patients with a compatible donor

Immunisation against Human Leucocyte Antigens (HLA) can be caused by pregnancy, blood transfusion, or organ transplants. The HLA antibody status of a given patient significantly influences their access and waiting time to transplant. For some highly sensitised patients (HSP) there is hardly any suitable donor available in the deceased donor pool of their allocation organisation and therefore they wait a very long time before being offered a kidney for transplant. Especially patients with rare HLA phenotypes in relation to the actual donor pool are waiting extremely long. As HLA phenotypes are different in the various European populations, we hypothesized that extension of the donor pool outside the respective allocation system will increase the chance of receiving a compatible transplant for this subgroup of highly sensitised patients. One of the objectives of the EUROSTAM project, (a Europe-wide Strategy to enhance Transplantation of highly sensitised patients on the basis of Acceptable HLA Mismatches) was to develop a tool to compare the chance of transplanting HSP in different European populations with donor organs from within and outside their own donor pool.Information on the HLA type and ABO blood group of the actual donor population, as well as the acceptable mismatches of long waiting HSP were obtained from the EUROSTAM partner organizations i.e. Eurotransplant (ET), UK National Health Service Blood and Transplant (NHSBT), Barcelona, Prague and Athens.Results from simulations using the newly developed tool shows that 195 (27%) of the 724 long waiting highly sensitised patients registered at each partner organisation have increased chances of transplant in a different European donor pool. This makes a strong case for sharing kidneys between European countries for selected difficult to transplant patients.     

A novel united network for organ sharing region kidney allocation plan improves transplant access for minority candidates

BACKGROUND: We report the consequences of a novel kidney allocation system on access of non-Caucasians (NC) to kidney transplantation. This new plan has provided a balance of allocation determinants between time waiting, HLA match, and geography (population density between donor and recipient center). METHODS: Three sequential systems of regional allocation were analyzed: period I (September 1994 to September 1996), period II (September 1996 to November 1997), and period III (December 1997 to March 1 1999). Periods II and III are reflective of the new allocation plan. RESULTS: During periods II and III, the NC rate of kidney transplantation increased closer to the NC proportion on the wait list, comparatively exceeding the national UNOS data. There was no statistical difference in regional mean wait time between Caucasian and NC. Improvements in access to transplantation for NCs between period I and periods II and III appear to be related to changes in geographic allocation weight from local unit to population density points, to the inclusion of the entire region in the plan, and to the deletion of intermediate degrees of B/DR mismatching in the revised plan. Despite the increased proportion of NCs on the wait list from period I to period III, the percentage difference between the proportion of NCs waiting on the list and the proportion NCs receiving a transplant fell from 7.8% to 4.9%. CONCLUSIONS: These data demonstrate that this new allocation plan was associated with improved access of minority candidates to transplantation. The broadening of geographic allocation and the alteration of HLA points appear to permit a more favorable opportunity for renal transplantation to NC candidates. selection, compared to the UNOS formula. In this report, we analyze the consequences of the Region 1 allocation system on the access of non-Caucasian (NC) candidates to cadaver donor kidney transplantation.     

An evaluation of HLA cross-reactive group matching on graft survival in deceased donor kidney recipients

Since September 20, 1999, our organ procurement organization (OPO) serving an ethnically diverse local distribution area has allocated kidneys using a cross-reactive group (CREG)-based variance. This variance awards 7 points for 0-CREG,0-DR mismatches and 6 points for 0-A,B mismatches in addition to points given for waiting time (3) and panel-reactive antibodies (PRA) > or = 80% (3). Previously, we have shown that awarding points for 0-CREG,0-DR mismatches in kidney allocation improves the access to HLA-matched transplants for racial groups, especially for the black race. In this study, we evaluated if there are outcome benefits as well. One- and 3-year uncensored graft survival data and analyses for the influence of HLA mismatching on graft outcome in black and nonblack recipients were provided by Scientific Registry of Transplant Recipients (SRTR). Overall, 1-year graft survival was 87.4% and not significantly different for blacks (86.1%, n = 467) vs nonblacks (88.8%, n = 730); 3-year graft survival was 74.6% and significantly lower P = .0001 for blacks (68.5%, n = 480) vs nonblacks (78.4%, n = 765). No significant advantage was observed for either the black or nonblack recipients in any of the HLA-mismatched categories, including the 0-CREG,0-DR mismatch group. An HLA matching effect also was not seen when data were stratified for patients nonsensitized (PRA < or = 10%) and sensitized (PRA > 10%) at the time of transplantation, except for the improved graft survival in sensitized nonblack recipients of 0- A,B,DR-mismatched grafts. Of the patients who lost their grafts and returned to the waiting list for retransplantation, the 0-A,B,DR mismatched were the least sensitized group (6%, n = 16), and there was a trend for less sensitization in the 0-CREG,0-DR-mismatched group (33%, n = 9), compared to those with other HLA mismatches (68%, n = 137). Thus, based on 1-year and 3-year follow-up data, there are no apparent graft outcome benefits for either CREG matching or conventional HLA matching in our service area, except for sensitized nonblack recipients receiving 0-A,B,DR-mismatched grafts. Such benefits may become more apparent with longer follow-up.     

Comparison of time on the deceased donor kidney waitlist versus time on the kidney paired donation registry in the Australian program

In the Australian kidney paired donation (KPD) program matching is based on acceptable mismatches, whereas deceased donor waitlist (DDWL) patients are allocated kidneys based on HLA antigen matching rules. Herein, we compared waiting time for a KPD match to the waiting time on the DDWL and the occurrence of matching in the DDWL for patients who were registered in both programs. Data on first dialysis, matches on the DDWL, KPD program entry, matches and transplant dates were assessed in 26 KPD recipients of the Australian program. There were 22 recipients who were listed in the DDWL and received kidney transplants by KPD. Time on dialysis until KPD transplantation was 808 ± 646 days. Eleven patients had never been matched with a deceased donor (waiting time 345 ± 237 days) and 11 had been matched on average 3 ± 5 times (waiting time 1227 ± 615 days, P < 0.0001 vs. never matched), but did not progress to transplantation because of positive crossmatch or class II donor‐specific antibody. Mean time from registration in the KPD program until kidney transplantation was 153 ± 92 days (P < 0.0001 vs. DDWL). KPD allocation using the acceptable mismatch approach is effective in identifying suitable live donors for some recipients within a relatively short time‐frame.     

Characterization of Waiting Times in a Simulation of Kidney Paired Donation

A national kidney paired donation (KPD) program will substantially increase transplant opportunities for recipients with blood type incompatible or cross-match positive donors. It seems likely that donor-recipient pairs with certain blood types, races or restrictions will wait longer than others for a match, although no data exist to confirm this assumption. We simulated patients and characterized the predicted waiting times for different blood type sub-groups, as well as the effects of patient-imposed restrictions on waiting time. We also compared waiting times of different racial sub-groups. Almost all patients with panel-reactive antibody (PRA) less than 80% match within a few months in a national KPD program, with the longest waiting time seen by O recipients with AB donors. Highly sensitized patients wait considerably longer, especially those unwilling to travel or accept older donors, and those with AB or B donors may not match in a timely manner. Although patients are better served by matching in a combined pool than within their own race, racial inequalities exist and bonus points can offset some of these differences. These data provide the first waiting time predictions that can aid patients with incompatible donors in choosing between KPD and desensitization, and can also facilitate planning for a national KPD program.     

An algorithm for cadaver kidney allocation based on a multivariate analysis of factors impacting on cadaver kidney graft survival and function

Abstract The large imbalance between cadaver kidney supply and demand makes the implementation of equitable and effective organ allocation systems an urgent need. This has triggered a revision of the criteria used so far for cadaver kidney allocation within the North Italy Transplant program, not least in the light of the many changes that have occurred recently with respect to broader criteria for admission of patients to the waiting list, donor selection, tissue‐typing methods, organ preservation and immunosuppressive protocols. We based the critical revision of our cadaver kidney allocation algorithm on univariate and multivariate analysis of a number of immunological, clinical, social and administrative factors that impacted on the transplant outcome in 2,917 patients transplanted in the 12 transplant centers operating within our organization from 1 January 1990 to 30 September 1997. This analysis indicated that younger donor age, absence of pretransplant transfusions, patient dialysis center and level of HLA match showed statistically significant positive associations with graft survival. Younger donor age and male donor gender showed a statistically significant association with excellent graft function at 4 years. The results of this analysis were used to develop a new computer‐assisted version of our adult kidney allocation algorithm. It works in two steps (local pool first, then the entire waiting list) and four levels (0‐1 HLA MM, PRA +; 2 HLA MM, PRA +; 0‐1 MM, PRA‐; 2‐4 HLA MM, PRA‐); within each level, selection takes into account waiting time and age difference from donor age. The evaluation of 731 transplants allocated in 19 months with the new algorithm, as against 698 transplants allocated in the preceding 19 months according to the previous algorithm, showed a significantly higher proportion of recipients who had been on the waiting list for more than 3 years (33.2% versus 22.6%). The use of the new algorithm was also associated with a significantly increased number of transplanted alloimmunized patients (18.8% versus 9.2% with the previous algorithm) and recipients with 0‐1 HLA mismatches (22% versus 14.3%). Furthermore, the number of kidneys used locally has steadily increased. Differences in 6‐month graft survival and percentage of patients with excellent function at 6 months were not statistically significant in recipients transplanted with the new versus the previous algorithm. Survivals were 93.7% versus 91.8%. Percentages of patients with excellent renal function were 69.9% and 71.8%, respectively. These preliminary data suggest that the new algorithm improves HLA match and reduces the number of patients on the waiting list for 3 or more years without determining significant modifications of 6‐month graft survival and function. Moreover, it facilitates the achievement of a fair local balance between organs retrieved and transplanted, the compliance of operators with objective allocation rules and the documentation of the whole allocation process.     

Beneficial effect of matching at the HLA-A and -B amino-acid triplet level on rejection-free clear graft survival in penetrating keratoplasty

OBJECTIVE: The beneficial effect of human leukocyte antigen (HLA) matching on long-term prognosis in penetrating keratoplasty is now unequivocal but has to be weighed against the additional waiting period on an individual basis. HLAMatchmaker is a molecularly based algorithm for histocompatibility determination that can identify immunologically acceptable mismatches and thus potentially reduce time on the waiting list dramatically without negatively affecting prognosis. METHODS: The HLAMatchmaker algorithm (triplet-string matching) was applied on each of 545 normal-risk keratoplasties for which complete HLA type was known at split-level resolution. Two homogeneous groups were defined. Group I consisted of the 147 penetrating keratoplasties with up to 13 triplet-string mismatches (the typical upper limit of foreign in case of a single HLA-A or HLA-B allele mismatch) and was compared to the remaining 398 patients with more triplet mismatches (group II) using the Kaplan-Meier method and log-rank statistics. Analysis of clear graft survival on the basis of conventional HLA-A and HLA-B matching was performed as well. Reduction of time on the waiting list as compared to conventional HLA-A and HLA-B matching was predicted individually. RESULTS: Triplet-string matching yielded 85% rejection-free clear graft survival 3 years after penetrating keratoplasty in group I but only 76% in group II (P<0.05), whereas conventional HLA-A and HLA-B matching did not result in any statistically significant reduction of immune reactions because of lack of statistical power (P=0.08). Triplet-string matching (13 mismatches accepted) reduces median time on the waiting list by 80%. CONCLUSIONS: Triplet-string matching seems to improve mid- to long-term prognosis in penetrating keratoplasties while simultaneously reducing time on the waiting list in most cases. It should thus be considered for histocompatibility determination in penetrating keratoplasty.     

Prospective Age-Matching in Elderly Kidney Transplant Recipients—A 5-Year Analysis of the Eurotransplant Senior Program

Renal transplantation faces challenges: the organ shortage resulting in extended waiting times and an aging population resulting in death with a functioning graft. The Eurotransplant Senior Program (ESP) allocates kidneys within a narrow geographic area from donors aged ≥65 years to recipients ≥65 years regardless of HLA. This analysis investigates the impact of the ESP on waiting time, graft and patient survival. The ESP group (n = 1406, old to old) was compared to two groups allocated via the Eurotransplant Kidney Allocation System (ETKAS) with either similar donor age (old to any [O/A], donor age ≥65, n = 446) or recipient age (any to old, [A/O], recipient age 60–64, n = 1687). All patients were transplanted between 1999 and 2004. Since initiation of the ESP (1999), availability of elderly donors doubled and waiting time for ESP patients decreased. Local allocation led to shorter cold ischemia time (11.9 vs. >17.0 h, p < 0.001) and less delayed graft function (DGF, ESP 29.7% vs. O/A 36.2%, p = 0.047) but 5–10% higher rejection rates. Graft and patient survival were not negatively affected by the ESP allocation when compared to the standard allocation. The ESP age matching of elderly donors and recipients is an effective allocation system for organs from elderly donors.     

Review of the Uruguayan Kidney Allocation System: The Solution to a Complex Problem, Preliminary Data

The National Kidney Transplant Program with cadaveric donors is based on centralized and unique waitlist, serum bank, and allocation criteria, approved by Instituto Nacional de Donación y Trasplante (INDT) in agreement with clinical teams. The median donor rates over last 3 years is 20 per million population and the median number of waitlist candidates is 450. The increased number of waiting list patients and the rapid aging of our populations demanded strategies for donor acceptance, candidate assignment, and analysis of more efficient and equitable allocation models.The objectives of the new national allocation system were to improve posttransplant patient and graft survivals, allow equal access to transplantation, and reduce waitlist times. The objective of this study was to analyze variables in our current allocation system and to create a mathematical/simulation model to evaluate a new allocation system. We compared candidates and transplanted patients for gender, age, ABO blood group, human leukocyte agents (HLA), percentage of reactive antibodies (PRA), and waiting list and dialysis times. Only 2 factors showed differences: highly sensitized and patients >65 years old (Bernoulli test).An agreement between INDT and Engineering Faculty yielded a major field of study. During 2008 the data analysis and model building began. The waiting list data of the last decade of donors and transplants were processed to develop a virtual model. We used inputs of candidates and donors, with outputs and structure of the simulation system to evaluate the proposed changes. Currently, the INDT and the Mathematics and Statistics Institute are working to develop a simulation model, that is able to analyze our new national allocation system.     

Allocation of Deceased Donor Kidneys in São Paulo, Brazil: Effect of Human Leukocyte Antigen Compatibility on Graft Survival

In Brazil, organ transplantation has been regulated by a federal law since 1997. This law was created to guarantee equal access to treatment on a national scale. Deceased donor organ procurement and sharing are centralized and controlled by the Health Department of each state of the nation, following a regional allocation policy. In São Paulo, time on the waiting list was the main criterion adopted to allocate deceased donor kidneys up to January 1, 2002. After that, HLA mismatches (MM) were the main criterion. The aim of this study was to investigate the impact of HLA compatibility on graft survival among 3312 consecutive kidney recipients. The 2-year kidney graft survival rates were compared among recipients transplanted based on the waiting time policy and based on HLA MM. Better results were observed in the HLA MM group (78.1% vs 64.9%; P < .0001). Regarding kidney allocation based on HLA MM, recipients transplanted with 0 HLA-A, -B, or -DR MM showed significantly better 5-year survival rates than those with 1-2 or 3-4 or 5-6 HLA-A, -B, or -DR MM (70.36% vs 64.71% vs 58.07% vs 55.64%; P < .050). We concluded that HLA compatibility is a feasible criterion to allocate deceased donor kidneys in Brazil.     

Evolution in allocation rules for renal, hepatic, pancreatic and intestinal grafts

Organ transplantation is the victim of his own success. The results of transplantation are excellent and more patients are activated on the waiting list. The need for organs exceeds the supply. Which criteria are used to allocate available grafts to patients on the waiting list ? Organ allocation and finding the "best match" between donor and recipients, is the goal of Eurotransplant, the organ sharing organization for seven European countries (Austria, Croatia, Germany, Luxemburg, Slovenia, The Netherlands and Belgium). Last decade, the allocation system has switched from a "center-driven" (organ allocated to a center) to a "patient-driven" system (organ allocated to a particular patient). For the allocation of abdominal organs some general allocation rules are followed: blood group compatibility, priority for high urgencies. The allocation of kidneys is based on a point score system based on waiting time, HLA and donor location (to reduce the cold ischemia time). In addition to this standard allocation procedure, there are still specific procedures for pediatric recipients and for candidates > or = 65 year old. There is also an "acceptable" mismatch program for recipients at high immunological risk. The liver allocation system recently changed and is now based on the MELD score, a formula that calculates the probability of death within 3 months on the waiting list. For pancreas and intestine, the system is based on blood group, medical urgency, waiting time, donor region and weight (for intestine).