John S. Gill

Consensus guidelines on the testing and clinical management issues associated with HLA and non-HLA antibodies in transplantation.

Background The introduction of solid-phase immunoassay (SPI) technology for the detection and characterization of human leukocyte antigen (HLA) antibodies in transplantation while providing greater sensitivity than was obtainable by complement-dependent lymphocytotoxicity (CDC) assays has resulted in a new paradigm with respect to the interpretation of donor-specific antibodies (DSA). Although the SPI assay performed on the Luminex instrument (hereafter referred to as the Luminex assay), in particular, has permitted the detection of antibodies not detectable by CDC, the clinical significance of these antibodies is incompletely understood. Nevertheless, the detection of these antibodies has led to changes in the clinical management of sensitized patients. In addition, SPI testing raises technical issues that require resolution and careful consideration when interpreting antibody results. Methods With this background, The Transplantation Society convened a group of laboratory and clinical experts in the field of transplantation to prepare a consensus report and make recommendations on the use of this new technology based on both published evidence and expert opinion. Three working groups were formed to address (a) the technical issues with respect to the use of this technology, (b) the interpretation of pretransplantation antibody testing in the context of various clinical settings and organ transplant types (kidney, heart, lung, liver, pancreas, intestinal, and islet cells), and (c) the application of antibody testing in the posttransplantation setting. The three groups were established in November 2011 and convened for a “Consensus Conference on Antibodies in Transplantation” in Rome, Italy, in May 2012. The deliberations of the three groups meeting independently and then together are the bases for this report. Results A comprehensive list of recommendations was prepared by each group. A summary of the key recommendations follows. Technical Group: (a) SPI must be used for the detection of pretransplantation HLA antibodies in solid organ transplant recipients and, in particular, the use of the single-antigen bead assay to detect antibodies to HLA loci, such as Cw, DQA, DPA, and DPB, which are not readily detected by other methods. (b) The use of SPI for antibody detection should be supplemented with cell-based assays to examine the correlations between the two types of assays and to establish the likelihood of a positive crossmatch (XM). (c) There must be an awareness of the technical factors that can influence the results and their clinical interpretation when using the Luminex bead technology, such as variation in antigen density and the presence of denatured antigen on the beads. Pretransplantation Group: (a) Risk categories should be established based on the antibody and the XM results obtained. (b) DSA detected by CDC and a positive XM should be avoided due to their strong association with antibody-mediated rejection and graft loss. (c) A renal transplantation can be performed in the absence of a prospective XM if single-antigen bead screening for antibodies to all class I and II HLA loci is negative. This decision, however, needs to be taken in agreement with local clinical programs and the relevant regulatory bodies. (d) The presence of DSA HLA antibodies should be avoided in heart and lung transplantation and considered a risk factor for liver, intestinal, and islet cell transplantation. Posttransplantation Group: (a) High-risk patients (i.e., desensitized or DSA positive/XM negative) should be monitored by measurement of DSA and protocol biopsies in the first 3 months after transplantation. (b) Intermediate-risk patients (history of DSA but currently negative) should be monitored for DSA within the first month. If DSA is present, a biopsy should be performed. (c) Low-risk patients (nonsensitized first transplantation) should be screened for DSA at least once 3 to 12 months after transplantation. If DSA is detected, a biopsy should be performed. In all three categories, the recommendations for subsequent treatment are based on the biopsy results. Conclusions A comprehensive list of recommendations is provided covering the technical and pretransplantation and posttransplantation monitoring of HLA antibodies in solid organ transplantation. The recommendations are intended to provide state-of-the-art guidance in the use and clinical application of recently developed methods for HLA antibody detection when used in conjunction with traditional methods.

Sirolimus Is Associated with New-Onset Diabetes in Kidney Transplant Recipients

New-onset diabetes (NOD) is associated with transplant failure. A few single-center studies have suggested that sirolimus is associated with NOD, but this is not well established. With the use of data from the United States Renal Data System, this study evaluated the association between sirolimus use at the time of transplantation and NOD among 20,124 adult recipients of a first kidney transplant without diabetes. Compared with patients treated with cyclosporine and either mycophenolate mofetil orazathioprine, sirolimus-treated patients were at increased risk for NOD, whether it was used in combination with cyclosporine (adjusted hazard ratio [HR] 1.61; 95% confidence interval [CI] 1.36 to 1.90),tacrolimus (adjusted HR 1.66; 95% CI 1.42 to 1.93), or an antimetabolite (mycophenolate mofetil orazathioprine; adjusted HR 1.36; 95% CI 1.09 to 1.69). Similar results were obtained in a subgroup analysis that included the 16,861 patients who did not have their immunosuppressive regimen changed throughout the first posttransplantation year. In conclusion, sirolimus is independently associated with NOD. Given the negative impact of NOD on posttransplantation outcomes, these findings should be confirmed in prospective studies or in meta-analyses of existing trials that involved sirolimus.

Impact of Acute Rejection and New-Onset Diabetes on Long-Term Transplant Graft and Patient Survival

BACKGROUND AND OBJECTIVES Development of new therapeutic strategies to improve long-term transplant outcomes requires improved understanding of the mechanisms by which these complications limit long-term transplant survival. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS The association of acute rejection and new-onset diabetes was determined in the first posttransplantation year with the outcomes of transplant failure from any cause, death-censored graft loss, and death with a functioning graft in 27,707 adult recipients of first kidney-only transplants, with graft survival of at least 1 yr, performed between 1995 and 2002 in the United States. RESULTS In multivariate analyses, patients who developed acute rejection or new-onset diabetes had a similar risk for transplant failure from any cause, but the mechanisms of transplant failure were different: Acute rejection was associated with death-censored graft loss but only weakly associated with death with a functioning graft. In contrast new-onset diabetes was not associated with death-censored graft loss but was associated with an increased risk for death with a functioning graft. CONCLUSIONS Acute rejection and new-onset diabetes have a similar impact on long-term transplant survival but lead to transplant failure through different mechanisms. The mechanisms by which new-onset diabetes leads to transplant failure should be prospectively studied. Targeted therapeutic strategies to minimize the impact of various early posttransplantation complications may lead to improved long-term outcomes.

Outcomes of Kidney Transplantation From Older Living Donors to Older Recipients

BACKGROUND More than half the newly wait-listed patients for kidney transplantation in 2005 were older than 50 years, and 13% were older than 65 years. As waiting times for a deceased donor kidney increase, these older candidates are disadvantaged by rapidly deteriorating health, often resulting in death or removal from the wait list before transplantation. STUDY DESIGN An observational cohort study was conducted using data from the Organ Procurement Transplant Network/United Network for Organ Sharing. SETTING & PARTICIPANTS All adult kidney-only transplantations performed in recipients 60 years and older from 1996 to 2005 were included. PREDICTOR The recipient cohort was stratified into 4 groups based on donor source: older living donor (OLD: living donor age > 55 years), younger living donor (YLD: living donor age </= 55 years), standard criteria deceased donor (SCD), and expanded criteria deceased donor (ECD). OUTCOMES & MEASUREMENTS Early posttransplantation outcomes, graft survival, patient survival, renal function 1 year posttransplantation, and relative risk of graft loss and patient death were compared. RESULTS Of 23,754 kidney transplantations performed in recipients 60 years and older, 7,006 were living donor transplantations (1,133 were > 55 years [OLD] and 5,873 were <or= 55 years [YLD]), 12,197 from SCDs, and 4,551 from ECDs. Early posttransplantation outcomes were best in YLD transplantations, followed by SCD and OLD transplantations. OLD transplantations were associated with inferior 3-year graft survival rates (85.7%), but similar 3-year patient survival rates (88.4%) compared with YLD (3-year graft survival, 83.4%; patient survival, 87.4%) and had superior graft survival compared with all deceased donor options. Compared with OLD transplantations, ECD transplantations were associated with a greater risk of graft loss (hazard ratio, 2.36; 95% confidence interval, 1.18 to 4.74). LIMITATIONS Observational retrospective studies using registry data are subject to inherent limitations, including the possibility of selection bias. CONCLUSIONS With superior graft and patient survival in recipients of transplants from OLDs compared with SCDs and ECDs, OLDs may be an important option for elderly transplantation candidates and should be considered for older patients with a willing and suitable older donor.

Trace elements in hemodialysis patients: a systematic review and meta-analysis

BackgroundHemodialysis patients are at risk for deficiency of essential trace elements and excess of toxic trace elements, both of which can affect health. We conducted a systematic review to summarize existing literature on trace element status in hemodialysis patients.MethodsAll studies which reported relevant data for chronic hemodialysis patients and a healthy control population were eligible, regardless of language or publication status. We included studies which measured at least one of the following elements in whole blood, serum, or plasma: antimony, arsenic, boron, cadmium, chromium, cobalt, copper, fluorine, iodine, lead, manganese, mercury, molybdenum, nickel, selenium, tellurium, thallium, vanadium, and zinc. We calculated differences between hemodialysis patients and controls using the differences in mean trace element level, divided by the pooled standard deviation.ResultsWe identified 128 eligible studies. Available data suggested that levels of cadmium, chromium, copper, lead, and vanadium were higher and that levels of selenium, zinc and manganese were lower in hemodialysis patients, compared with controls. Pooled standard mean differences exceeded 0.8 standard deviation units (a large difference) higher than controls for cadmium, chromium, vanadium, and lower than controls for selenium, zinc, and manganese. No studies reported data on antimony, iodine, tellurium, and thallium concentrations.ConclusionAverage blood levels of biologically important trace elements were substantially different in hemodialysis patients, compared with healthy controls. Since both deficiency and excess of trace elements are potentially harmful yet amenable to therapy, the hypothesis that trace element status influences the risk of adverse clinical outcomes is worthy of investigation.

Treatment of polyomavirus infection in kidney transplant recipients: a systematic review.

Background. Polyomavirus-associated nephropathy (PVAN) is an important cause of kidney graft loss but there is no consensus on its management. This study aimed to systematically document all published treatments for PVAN to determine the most effective therapy. Methods. A computerized search in MEDLINE, EMBASE, and Cochrane databases (1950–2008) was performed. References from review articles and published abstracts from the American Transplant Congress (2005–2008) were also included. Study selection criteria included (a) population: adult (>18 years) kidney-only, primary or repeat renal transplant recipients; (b) setting: polyoma viruria, viremia or biopsy-proven PVAN or both; and (c) treatment: immunosuppression reduction alone or with adjuvant agents. The primary outcome was graft failure rate, and secondary outcomes included acute rejection rate, elimination of viruria and viremia, graft function, patient survival, and adverse events. Results. Of 555 identified citations, 40 studies examining the effect of immunosuppression reduction alone or in combination with cidofovir, leflunomide, intravenous immunoglobulin, or ciprofloxacin were included for appraisal. Pooled results found a death-censored graft loss rate of 8/100 patient-years for immunosuppression reduction alone and 8 and 13/100 patient-years for the addition of cidofovir or leflunomide, respectively. Conclusions. There does not seem to be a graft survival benefit of adding cidofovir or leflunomide to immunosuppression reduction for the management of PVAN. However, the evidence base is poor and highlights the urgent need for adequately powered randomized trials to define the optimal treatment of this important condition.

Survival among nocturnal home haemodialysis patients compared to kidney transplant recipients

BACKGROUND Kidney transplantation is the gold standard renal replacement therapy. Nocturnal haemodialysis (NHD) is an intensive dialysis modality (6-8 h/session, 3-7 sessions/week) associated with a significant improvement of clinical and biochemical parameters compared to conventional dialysis. To date, no studies have compared survival in patients treated with NHD and kidney transplantation. METHODS Using data from two regional NHD programmes and the USRDS from 1994 to 2006, we performed a matched cohort study comparing survival between NHD and deceased and living donor kidney transplantation (DTX and LTX) by randomly matching NHD patients to transplant recipients in a 1:3:3 ratio. The independent association of treatment modality with survival was determined using Cox multivariate regression. RESULTS The total study population consisted of 177 NHD patients matched to 1062 DTX and LTX recipients (total 1239 patients) followed for a maximum of 12.4 years. During the follow-up period, the proportion of deaths among NHD, DTX and LTX patients was 14.7%, 14.3% and 8.5%, respectively (P = 0.006). We found no difference in the adjusted survival between NHD and DTX (HR 0.87, 95% CI 0.50-1.51; NHD reference group), while LTX survival was better (HR 0.51, 95% CI 0.28-0.91). CONCLUSIONS These results indicate that NHD and DTX survival is comparable, and suggest that this intensive dialysis modality may be a bridge to transplantation or even a suitable alternative in the absence of LTX in the current era of growing transplant waiting lists and organ shortage.

Cardiovascular disease and hypertension risk in living kidney donors: an analysis of health administrative data in Ontario, Canada.

Background. Knowledge of any harm associated with living kidney donation guides informed consent and living donor follow-up. Risk estimates in the literature are variable, and most studies did not use a healthy control group to assess outcomes attributable to donation. Methods. We observed a retrospective cohort using health administrative data for donations which occurred in Ontario, Canada between the years 1993 and 2005. There were a total of 1278 living donors and 6359 healthy adults who acted as a control group. Individuals were followed for a mean of 6.2 years (range, 1-13 years) after donation. The primary outcome was a composite of time to death or first cardiovascular event (myocardial infarction, stroke, angioplasty, and bypass surgery). The secondary outcome was time to a diagnosis of hypertension. Results. There was no significant difference in death or cardiovascular events between donors and controls (1.3% vs. 1.7%; hazard ratio 0.7, 95% confidence interval 0.4-1.2). Donors were more frequently diagnosed with hypertension than controls (16.3% vs. 11.9%, hazard ratio 1.4, 95% confidence interval 1.2-1.7) but were also seen more often by their primary care physicians (median [interquartile range] 3.6 [1.9-6.1] vs. 2.6 [1.4-4.3] visits per person year, P<0.001). Conclusions. Based on administrative data, the risk of cardiovascular disease was unchanged in the first decade after kidney donation. The observed increase in diagnosed hypertension may be due to nephrectomy or more blood pressure measurements received by donors in follow-up and requires prospective study.

The Change in Allograft Function among Long-Term Kidney Transplant Recipients

Long-term kidney allograft survival continues to remain an elusive goal. Kidney transplant recipients are believed to be at high risk for loss of allograft function, and new, potentially non-nephrotoxic immunosuppressive medications are advocated to improve long-term allograft survival. To evaluate the efficacy of such therapeutic interventions, information regarding the change in GFR among kidney transplant recipients with long-term allograft survival is needed. We studied 40,963 transplant recipients between 1987 and 1996 with allograft survival of at least 2 yr in the United States Renal Data System. Linear regression methods were applied to serial GFR estimates after transplantation. The baseline mean GFR at 6 mo after transplantation was 49.6 +/- 15.4 ml/min per 1.73 m(2). During the mean follow-up of 5.7 +/- 2.3 yr, the mean +/- standard error of the change in GFR was -1.66 +/- 6.51 ml/min per 1.73 m(2) per year (median, -0.94 L/min per 1.73 m(2) per year). A total of 12,583 (30%) of patients had improvement in GFR, 8133 (20%) patients had no change in GFR, and 20,247 (50%) patients had decline in GFR. It is concluded that, although most patients had significant impairment of GFR at baseline, the decline in GFR was slow and many patients had either no change or improvement in GFR. Strategies to improve long-term kidney allograft survival that increase baseline allograft function may be more effective than strategies to slow the decline in GFR.

Nephrectomy After Transplant Failure: Current Practice and Outcomes

The role of transplant nephrectomy after transplant failure is uncertain. We report the use and consequences of transplant nephrectomy among 19 107 transplant failure patients between 1995 and 2003 in the United States. Among 3707 patients with early transplant failure (graft survival <12 m), nephrectomy was performed in 56%, and was associated with an increased risk of death (HR 1.13, 95% CI 1.01–1.26). In contrast, among 15 400 patients with late transplant failure (graft survival ≥12 m), nephrectomy was performed in 27%, and was associated with a decreased risk of death (HR 0.89, 95% CI 0.83–0.95). In early transplant failure patients, nephrectomy was associated with a lower risk of repeat transplant failure (HR 0.72, 95% CI 0.56–0.94), while among late transplant failure patients; nephrectomy was associated with a higher risk of repeat transplant failure (HR 1.20, 95% CI 1.02–1.41). Definitive conclusions are not possible from this observational study. The role of nephrectomy in the management of dialysis treated transplant failure patients, and the implications of nephrectomy for repeat transplantation should be further studied in prospective studies.