A computer match program for paired and unconventional kidney exchanges

A Systematic Review of Kidney Transplantation Decision Modelling Studies

BACKGROUND

Genome-based precision medicine strategies promise to minimize premature graft loss after renal transplantation, through precision approaches to immune compatibility matching between kidney donors and recipients. The potential adoption of this technology calls for important changes to clinical management processes and allocation policy. Such potential policy change decisions may be supported by decision models from health economics, comparative effectiveness research and operations management.

OBJECTIVE

We used a systematic approach to identify and extract information about models published in the kidney transplantation literature and provide an overview of the status of our collective model-based knowledge about the kidney transplant process.

METHODS

Database searches were conducted in MEDLINE, Embase, Web of Science and other sources, for reviews and primary studies. We reviewed all English-language papers that presented a model that could be a tool to support decision making in kidney transplantation. Data were extracted on the clinical context and modelling methods used.

RESULTS

A total of 144 studies were included, most of which focused on a single component of the transplantation process, such as immunosuppressive therapy or donor-recipient matching and organ allocation policies. Pre- and post-transplant processes have rarely been modelled together.

CONCLUSION

A whole-disease modelling approach is preferred to inform precision medicine policy, given its potential upstream implementation in the treatment pathway. This requires consideration of pre- and post-transplant natural history, risk factors for allograft dysfunction and failure, and other post-transplant outcomes. Our call is for greater collaboration across disciplines and whole-disease modelling approaches to more accurately simulate complex policy decisions about the integration of precision medicine tools in kidney transplantation.

Concerns of ABO incompatible and crossmatch-positive potential donors and recipients about participating in kidney exchanges

Kidney paired exchanges (KPEs) have increased, yet are still underutilized. This study aimed to develop tools for assessing KPE concerns, identify predictors of KPE concerns, and describe common KPE concerns among potential living donors (LDs) and intended recipients. Incompatible former potential LDs (n = 135) and intended recipients (n = 83) retrospectively completed questionnaires to assess KPE concerns. Healthcare system distrust also was assessed. A minority (n = 48 or 36.5% of potential LDs; n = 25 or 30.1% of intended recipients) had pursued KPE participation. Of those who pursued KPE participation, 11 (22.9%) and 6 (24.0%) completed KPE donation or transplantation, respectively. The questionnaires for potential LDs and recipients showed good internal consistency and preliminary convergent validity. LDs and patients less willing to pursue KPE reported more KPE concerns. Common KPE concerns for both potential LDs and recipients were related to perceived Distrust/Inequity and Inconvenience/Cost. Multivariate predictors of more KPE concerns were as follows: male gender (t = 4.5, p < 0.001) and more healthcare system distrust (t = 2.5, p = 0.01) for potential LDs; black race (t = 2.1, p = 0.04) and more healthcare system distrust (t = 2.3, p = 0.03) for intended recipients. These findings underscore the importance of addressing concerns potential LDs and patients have about KPE if the true potential of KPE is to be realized.

Allocation and matching in kidney exchange programs

Living donor kidney transplantation is the preferred treatment for patients suffering from end-stage renal disease. To alleviate the shortage of kidney donors, many advances have been made to improve the utilization of living donors deemed incompatible with their intended recipient. The most prominent of these advances is kidney paired donation (KPD), which matches incompatible patient-donor pairs to facilitate a kidney exchange. This review discusses the various approaches to matching and allocation in KPD. In particular, it focuses on the underlying principles of matching and allocation approaches, the combination of KPD with other strategies such as ABO incompatible transplantation, the organization of KPD, and important future challenges. As the transplant community strives to balance quantity and equity of transplants to achieve the best possible outcomes, determining the right long-term allocation strategy becomes increasingly important. In this light, challenges include making full use of the various modalities that are now available through integrated and optimized matching software, encouragement of transplant centers to fully participate, improving transplant rates by focusing on the expected long-run number of transplants, and selecting uniform allocation criteria to facilitate international pools.

Single-center kidney paired donation: the Methodist San Antonio experience

Many potential kidney transplant recipients are unable to receive a live donor transplant due to crossmatch or blood type incompatibility. Kidney paired donation increases access to live donor transplantation but has been significantly underutilized. We established a kidney paired donation program including consented incompatible donor/recipient pairs as well as compatible pairs with older non-human leukocyte antigen identical donors. Over a 3-year period, a total of 134 paired donor transplants were performed, including 117 incompatible pairs and 17 compatible pairs. All transplants were done with negative flow cytometry crossmatches and five were done with desensitization combined with paired donation. Kidney paired donation transplants included two-way and three-way exchanges as well as three chains initiated by nondirected donors. Of the sensitized recipients transplanted by paired donation, 44% had calculated panel reactive antibody levels greater than 80%. Transplantation of females and prior transplant recipients was significantly higher with paired donation. Only three episodes of rejection occurred and no transplants were lost due to rejection. These data highlight the potential of kidney paired donation and suggest that all transplant centers should be actively engaged in paired donation to increase access to live donor transplantation.

Renal biomarkers for assessment of kidney function in renal transplant recipients: how do they compare?

Accurate assessment of renal function is of key importance, given its prognostic value. However, gold standard measures are cumbersome, and serum creatinine itself is an insensitive predictor, especially in renal transplant recipients. Though GFR-estimating formulae have been relied upon, they do have their own limitations. Nevertheless, renal biomarkers such as neutrophil gelatinase-associated lipocalin (NGAL) and cystatin C, among others, are now emerging as potentially useful indicators of GFR. We aimed to evaluate the diagnostic performance of NGAL versus cystatin C and eGFR using CKD-EPI, MDRD and cystatin C in renal transplant recipients and non-transplant CKD patients. We found a significant correlation between NGAL, serum creatinine, cystatin C and eGFR. The latter parameters were also strong predictors of serum NGAL levels. However, performance of NGAL, based on receiver operating characteristic curves, was inferior to that of the reference tests. It appears that in renal transplant recipients NGAL correlates well with cystatin C and eGFR, most strongly with cystatin-based formula. Though this suggests potential use of NGAL as a screening test, its weaker diagnostic performance raises some concern about its clinical usefulness. Larger studies are needed to explore this further.

Paired exchange kidney donation in India: a five-year single-center experience

INTRODUCTION

Paired exchange kidney donation (PKD) is an evolving strategy for overcoming the barriers that confront patients with end-stage renal disease, when the only living potential donors who are willing to donate to them are deemed to be unsuitable as donors for them owing to an incompatibility of blood type, of HLA cross-match, or of both. In the PKD, the incompatibility problems with two donor recipient pairs can be solved by exchanging donors. Although PKD is increasing worldwide, we in India have not nearly reached the estimated potential of this modality. Herein, we have reported our results with a living donor exchange program in past 5 years.

MATERIALS AND METHODS

Between March 2006 and June 2011, we performed 44 living PKD transplantations. All donor and recipient procedures were performed successfully. ABO incompatibility or positive lymphocyte cross-match were found in 20 pairs and 2 pairs, respectively.

RESULTS

The mean recipient age was 42.5 years (range 33-59 years). The mean donor age was 38 years (range 31-56 years). At a median follow-up of 33 months (range 1-59 months), graft survival rate was 100 %. All patients have functioning grafts with a median serum Creatinine level of 1.13, 1.5, and 1.35 mg/dl at 3 month, 1 year, and 3 years, respectively. One patient died after 4 month of transplant due to pneumonitis with sepsis. Allograft dysfunction was not seen in any of the recipients.

CONCLUSION

The PKD transplantation is a viable procedure medically and economically, which can be promoted in centers with a low deceased donor transplantation rate and a high number of incompatible related donors. We achieved excellent graft outcome by using the PKD transplantation program as an option to reduce the donor organ shortage.

Pediatric renal transplantation in a highly sensitised child-8 years on

Highly sensitised children have markedly reduced chances of receiving a successful deceased donor renal transplant, increased risk of rejection, and decreased graft survival. There is limited experience with the long-term followup of children who have undergone desensitization. Following 2 failed transplants, our patient was highly sensitised. She had some immunological response to intravenous immunoglobulin (IVIg) but this was not sustained. We developed a protocol involving sequential therapies with rituximab, IVIg, and plasma exchange. Immunosuppressant therapy at transplantation consisted of basiliximab, tacrolimus, mycophenolate mofetil, and steroids. At the time of transplantation, historical crossmatch was ignored. Current CDC crossmatch was negative, but T and B cell flow crossmatch was positive, due to donor-specific HLA Class I antibodies. Further plasma exchange and immunoglobulin therapy were given pre- and postoperatively. Our patient received a deceased donor-kidney-bearing HLA antigens to which she originally had antibodies, which would have precluded transplant. The graft kidney continues to function well 8 years posttransplant.

Donor exchange programs in kidney transplantation: rationale and operational details from the north central donor exchange cooperative

The increasing need for kidney transplants has led to innovations such as donor exchange programs. These programs offer transplant recipients with incompatible donors an opportunity to receive a compatible kidney. They also provide an alternative to costly desensitization protocols that have unproven long-term outcomes. Donor exchange programs have multiple options, including simple 2-pair exchanges, more complicated domino exchanges, or chain donations. The United States currently is limited by regional programs that provide for kidney donor exchanges. However, with the increasing public interest in and need for kidney transplants, general nephrologists will be approached with questions about these donor exchange programs. The goal of this review is to discuss donor exchange programs, including their role in expanding the donor pool, various types of exchanges, regional centers that provide these programs, and the process involved in patient enrollment. General knowledge of donor exchange programs will help providers in discussing options with patients approaching end-stage kidney disease and transplant.

Clinical outcomes of multicenter domino kidney paired donation

Domino kidney paired donation (KPD) is a method by which an altruistic living nondirected donor (LND) is allocated to a pool of incompatible donor-recipient pairs (DRP) and a series of KPDs is initiated. To evaluate the feasibility and clinical outcomes of multicenter domino KPD, we retrospectively analyzed a cohort of DRPs who underwent domino KPD between February 2001 and July 2007 at one of 16 transplant centers. One hundred seventy-nine kidney transplants were performed, with 70 domino chains initiated by altruistic LND. There were 45 two-pair chains, 15 three-pair chains, 7 four-pair chains, 2 five-pair chains and 1 six-pair chain. A majority of donors were spouses (47.5%) or altruistic LNDs (39.1%). DRPs with a blood type O recipient or an AB donor comprised 45.9% of transplanted DRPs. HLA mismatch improved in transplanted donors compared to intended donors in pairs enrolled to improve HLA mismatch (3.4 +/- 0.7 vs. 4.8 +/- 1.0, p < 0.001). One-year and 5-year graft survival rates were 98.3% and 87.7%, respectively, with a median follow-up of 46 months. One-year and 5-year patient survival rates were 97.2% and 90.8%, respectively. In conclusion, multicenter domino KPD could multiply the benefits of donation from LNDs, with patients and graft survival rates comparable to those seen with conventional KPD.

Utilization and outcomes of kidney paired donation in the United States

BACKGROUND

Kidney paired donation (KPD) offers the best transplant option for patients with incompatible live kidney donors. Although studies suggest substantial expansion of the donor pool if fully used, few patients in the United States have undergone KPD.

METHODS

We analyzed the 209 KPD and 89 list paired donation (LPD) transplants reported to United Network for Organ Sharing to better understand access to these modalities, clinical outcomes, and areas of potential expansion.

RESULTS

Although many centers offer KPD/LPD, most centers have performed no more than a handful of transplants. As expected, outcomes with KPD/LPD were equivalent to direct donation matched controls. In analyzing current practice, we identified two limitations to KPD in its current use. First, KPD is likely limited now by benefiting mostly patients who are easy to identify and match (such as A donors with B recipients or B donors with A recipients). Second, although some expansion of local KPD availability has reduced travel requirements for patients in those areas, significant room for growth remains.

CONCLUSIONS

Our results suggest that full utilization of KPD would encourage registration of and improve matching for patients who are more difficult to identify and match (such as highly sensitized recipients). Furthermore, expansion of KPD would likely reduce travel requirements and thereby improve access to this treatment modality.

Cross-over kidney transplantation with simultaneous laparoscopic living donor nephrectomy: initial experience

With cross-over living donor kidney transplantation, immunologic incompatibilities within the original donor/recipient pair can be overcome. As minimal invasive techniques for organ recovery are increasingly applied, this should also be performed in a cross-over kidney transplantation. We present the first report of a successful simultaneous laparoscopic kidney recovery for cross-over kidney transplantation as well as a review of the international practice of cross-over kidney transplantation in the context of national laws. Cross-over kidney transplantation should be encouraged. A databank on pairs willing to participate in organ exchange programs should be created.

Expanding kidney paired donation through participation by compatible pairs

In kidney paired donation (KPD), incompatible pairs exchange kidneys so that each recipient receives a compatible organ. This modality is underutilized partly because of the difficulty of finding a suitable match among incompatible pairs. Alternatively, recipients with compatible donors might enter KPD arrangements in order to be matched with a donor predicted to give greater allograft durability or for other altruistic reasons. Using simulated donors and recipients, we investigated the impact of allowing recipients and their compatible donors to participate in KPD. For KPD programs of any size, the participation of compatible donor/recipient pairs nearly doubled the match rate for incompatible pairs (28.2% to 64.5% for single-center program, 37.4% to 75.4% for national program). Legal, logistical, and governmental controversies have hampered the expansion of KPD in the United States by delaying the creation of a national program. The inclusion of compatible pairs into small single-center pools could achieve match rates that would surpass that which could be realized by a national list made up of only incompatible pairs. This new paradigm of KPD can immediately be instituted at the single-center level, while the greatest gains will be achieved by incorporating compatible pairs into a national program.

Posttransplant prophylactic intravenous immunoglobulin in kidney transplant patients at high immunological risk: a pilot study

The effects of posttransplant prophylactic intravenous immunoglobulin (IVIg) were investigated in renal transplant recipients at high immunological risk. Thirty-eight deceased-donor kidney transplant recipients with previous positive complement-dependent cytotoxicity crossmatch (n=30), and/or donor-specific anti-HLA antibodies (n=14) were recruited. IVIg (2 g/kg) was administrated on days 0, 21, 42 and 63 with quadruple immunosuppression. Biopsy-proven acute cellular and humoral rejection rates at month 12 were 18% and 10%, respectively. Glomerulitis was observed in 31% and 60% of patients at months 3 and 12, respectively, while allograft glomerulopathy rose from 3% at month 3 to 28% at 12 months. Interstitial fibrosis/tubular atrophy increased from 18% at day 0 to 51% and 72% at months 3 and 12 (p<0.0001). GFR was 50 +/- 17 mL/min/1.73 m(2) and 48 +/- 17 mL/min/1.73 m(2) at 3 and 12 months. PRA decreased significantly after IVIg (class I: from 18 +/- 27% to 5 +/- 12%, p<0.01; class II: from 25 +/- 30% to 7 +/- 16%, p<0.001). Patient and graft survival were 97% and 95%, respectively and no graft was lost due to rejection (mean follow-up 25 months). In conclusion, prophylactic IVIg in high-immunological risk patients is associated with good one-year outcomes, with adequate GFR and a profound decrease in PRA level, but a significant increase in allograft nephropathy.

14th International HLA and Immunogenetics Workshop: Report on understanding antibodies in transplantation

A session of the 14 International Histocompatibility Workshop brought together experts representing the major clinical protocols, clinical research, and basic research dealing with overcoming the barrier of alloantibody in transplantation and in understanding the mechanisms by which those antibodies exert their effect on a transplanted organ. This report is an integration of the presentations of those scientists.

Outcome of Multipair Donor Kidney Exchange by a Web-Based Algorithm

Donor kidney exchange is an established method to overcome incompatibility of donor-recipient pairs (DRP). A computerized algorithm was devised to exchange donor kidney and was tested in a multicenter setting. The algorithm was made according to the consensus of participating centers. It makes all possible exchange combinations not only between two incompatible DRP but also circularly among three DRP and selects an optimum set of exchange combinations, considering several factors that can affect the outcome of the exchanged transplant. The algorithm was implemented as a web-based program, and matching was performed five times. Fifty-three DRP were enrolled from five transplant centers. The numbers of DRP that were enrolled in each matching were 38 (25:13), 39 (34:5), 33 (31:2), 32 (28:4), and 34 (30:4) (carryover:newcomer). The numbers of generated exchange combinations were 4:11, 3:17, 2:12, 2:3, and 2:3 (two-pair exchange:three-pair exchange), and the numbers of DRP in selected exchange combinations were six, 12, six, five, and four in each matching. The numbers of DRP with blood type O recipient or AB donor were five and one, respectively, in selected exchange combinations. Six DRP of two-pair exchange combinations and six DRP of three-pair exchange combinations underwent transplantation successfully. Computerized algorithm of donor kidney exchange was tried not only between two incompatible DRP but also circularly among three DRP. It showed that the algorithm has potential to improve the outcome of donor kidney exchange, especially for disadvantaged DRP with blood type O recipients or AB donors.

Living donor renal transplantation: recent developments and perspectives

Renal transplantation is the optimal treatment for patients of all ages with end-stage renal disease. Life expectancy of the population in general is increasing consistently, as is the age of the dialysis population. Consequently, the average ages of kidney donors and recipients are rising. The combination of a growing number of patients with end-stage renal disease and a shortage of organs poses a significant challenge to the transplant community. Donor shortage is associated with unfavorable consequences (e.g. prolonged waiting time, and compromised graft and patient survival). As such, multidirectional efforts are required to expand the donor pool. Increasing the frequency of living donation seems to be an efficient solution. Living donation is associated with superior results for the recipient, and relatively benign long-term outcomes for donors. Reluctance to use organs from living donors whose eligibility was previously considered marginal (e.g. elderly donors) is declining. Although increased donor age is associated with reduced graft survival rates, this should not preclude use of older living donors; transplantation is definitely superior to remaining on dialysis. Thorough, standardized evaluation and careful screening for premorbid conditions in both elderly donors and elderly recipients are essential. Here, we present various options for expanding the living donor pool, with emphasis on the utilization of elderly living donors and transplantation in elderly recipients.

Transplantation across previously incompatible immunological barriers

This article reviews recent advances, which allow the transplantation across or around previously incompatible immunological barriers such as a positive crossmatch or ABO blood group incompatibility.

Presensitization: the problem and its management

Much attention has been placed recently on transplantation in highly HLA-sensitized patients. In attempts to remove these antibodies and enable successful transplantation, several novel approaches have been developed. These include intravenous Ig (IVIg), mycophenolate mofetil, sirolimus, alemtuzumab, protein A immunoabsorption, and rituximab. IVIg has emerged as a very effective agent when used alone in high dose or when used in low dose and combined with plasmapheresis. Although alemtuzumab has been used to eliminated B cells, it fails to prevent antibody-mediated rejection and therefore probably is not suitable for desensitization. Rituximab, a B cell-specific antibody, seems to be safe and to have some efficacy as a sole agent in elimination of alloantibodies but most likely will require combination therapy with IVIg or other agents. Newer agents, such as humanized anti-CD20, are being developed. Despite the great interest in the problem of allosensitization, with one notable exception, there is a major deficiency in controlled clinical trials, the conduct of which should be a focus for the near future.

Intravenous gammaglobulin (IVIG): a novel approach to improve transplant rates and outcomes in highly HLA-sensitized patients

Intravenous immunoglobulin (IVIG) products are derived from pooled human plasma and have been used for the treatment of primary immunodeficiency disorders for more than 24 years. Shortly after their introduction, IVIG products were also found to be effective in the treatment of autoimmune and inflammatory disorders. Over the past 2 decades, the list of diseases where IVIG has a demonstrable beneficial effect has grown rapidly. These include Kawasaki disease, Guillain-Barre syndrome, myasthenia gravis, dermatomyositis and demyelinating polyneuropathy. Recently, we have described a beneficial effect on the reduction of anti-HLA antibodies with subsequent improvement in transplantation of highly HLA-sensitized patients as well as a potent anti-inflammatory effect that is beneficial in the treatment of antibody-mediated rejection (AMR). These advancements have enabled transplantation of patients previously considered untransplantable. These studies and relevant mechanism(s) of action will be discussed here.