Renal allograft survival: getting better all the time

The economic burden of kidney graft failure in the United States

Despite improvements in outcomes for kidney transplant recipients in the past decade, graft failure continues to impose substantial burden on patients. However, the population-wide economic burden of graft failure has not been quantified. This study aims to fill that gap by comparing outcomes from a simulation model of kidney transplant patients in which patients are at risk for graft failure with an alternative simulation in which the risk of graft failure is assumed to be zero. Transitions through the model were estimated using Scientific Registry of Transplant Recipients data from 1987 to 2017. We estimated lifetime costs, overall survival, and quality-adjusted life-years (QALYs) for both scenarios and calculated the difference between them to obtain the burden of graft failure. We find that for the average patient, graft failure will impose additional medical costs of $78 079 (95% confidence interval [CI] $41 074, $112 409) and a loss of 1.66 QALYs (95% CI 1.15, 2.18). Given 17 644 kidney transplants in 2017, the total incremental lifetime medical costs associated with graft failure is $1.38B (95% CI $725M, $1.98B) and the total QALY loss is 29 289 (95% CI 20 291, 38 464). Efforts to reduce the incidence of graft failure or to mitigate its impact are urgently needed.

Ex vivo expanded natural regulatory T cells from patients with end-stage renal disease or kidney transplantation are useful for autologous cell therapy

Novel concepts employing autologous, ex vivo expanded natural regulatory T cells (nTreg) for adoptive transfer has potential to prevent organ rejection after kidney transplantation. However, the impact of dialysis and maintenance immunosuppression on the nTreg phenotype and peripheral survival is not well understood, but essential when assessing patient eligibility. The current study investigates regulatory T-cells in dialysis and kidney transplanted patients and the feasibility of generating a clinically useful nTreg product from these patients. Heparinized blood from 200 individuals including healthy controls, dialysis patients with end stage renal disease and patients 1, 5, 10, 15, 20 years after kidney transplantation were analyzed. Differentiation and maturation of nTregs were studied by flow cytometry in order to compare dialysis patients and kidney transplanted patients under maintenance immunosuppression to healthy controls. CD127 expressing CD4⁺CD25^highFoxP3⁺ nTregs were detectable at increased frequencies in dialysis patients with no negative impact on the nTreg end product quality and therapeutic usefulness of the ex vivo expanded nTregs. Further, despite that immunosuppression mildly altered nTreg maturation, neither dialysis nor pharmacological immunosuppression or previous acute rejection episodes impeded nTreg survival in vivo. Accordingly, the generation of autologous, highly pure nTreg products is feasible and qualifies patients awaiting or having received allogenic kidney transplantation for adoptive nTreg therapy. Thus, our novel treatment approach may enable us to reduce the incidence of organ rejection and reduce the need of long-term immunosuppression.

Antibody-mediated rejection implies a poor prognosis in kidney transplantation: Results from a single center

Two major barriers to achieving long-term graft survival include patient nonadherence in taking the prescribed immunosuppression and antibody-mediated rejection(AMR). We were therefore interested in determining the prognostic impact of developing an AMR component to rejection in a prospective randomized trial of 200 kidney transplant recipients who received dual induction therapy (rATG combined with either daclizumab or alemtuzumab) and planned early corticosteroid withdrawal. With a median follow-up of 96 months post-transplant, 40/200 developed a first BPAR; 9/200 developed a second BPAR. An AMR component to rejection was observed in 70% (28/40) of cases. Percentages having C4d deposition, histopathologic evidence of acute AMR, and presence of DSAs/non-DSAs at the time of first developing the AMR component were 64.3% (18/28), 60.7% (17/28), and 53.6% (15/28), respectively. Development of an AMR component was associated with a significantly higher death-censored graft failure rate following rejection in comparison with the patient state of experiencing BPAR but without developing an AMR component (estimated hazard ratio: 4.52, P = 0.01). The observed percentage developing graft failure following development of an AMR component was 53.6% (15/28) vs only 20.0%(3/15) if it was not observed. Actuarial death-censored graft survival at 60 months following development of an AMR component was 28.3 ± 11.9%. In summary, it appears that more effective AMR prevention/treatment strategies are warranted.

Lack of significant improvements in long-term allograft survival in pediatric solid organ transplantation: A US national registry analysis

Improvements across many facets of transplantation have led to better 1-yr outcomes of transplanted organs. In this study, we assessed whether longer-term attrition rates improved in pediatric kidney (KI), liver (LI), heart (HR) and lung (LU) transplant (TX) survival. We analyzed data between 1989 and 2008 from 5747 KI, 7348 LI, 5103 HR, and 715 LU TXs (under 18 yr of age at transplant, first solitary transplant only), from the National Scientific Registry of Transplant Recipients database in the USA. Kaplan-Meier (K-M) or ordinary least square (OLS) estimates were used to calculate median and projected survival half-lives. Attrition rates, defined as percent failing within a given time period, were stratified by year of TX. Median half-lives from 1989 TX year to 2005 TX year have shown a major improvement only in LI TX, remaining unchanged in HR and KI TX, or remaining very low in LU TX. All four organ TX types have shown a dramatic drop in first-year attrition rates from 1989 to 2008. However, longer-term attrition rates (1-3, 3-5, 5-10 yr) have remained largely unchanged for all four organ TX types. Further progress in long-term survival will need targeting end-points beyond first-year rejection and survival rates.

Graft failure due to noncompliance among 628 kidney transplant recipients with long-term follow-up: a single-center observational study

BACKGROUND

In adult kidney transplantation, there is no clear consensus on the incidence of graft failure-due-to noncompliance (GFNC), with some reporting it as relatively uncommon and others as a major cause of late graft failure. We suspected that GFNC was a major cause of late graft loss at our center but did not know the extent of this problem.

METHODS

In our prospectively followed cohort of 628 adult, primary kidney-alone transplant recipients with long-term follow-up, GFNC and other graft loss causes were determined from our ongoing clinical evaluations. Using competing risks methodology, we determined the overall percentage of patients developing GFNC and the significant prognostic factors for its hazard rate and cumulative incidence (via Cox regression).

RESULTS

Cumulative incidence estimates (± standard error) of GFNC (n=29), GF-with-compliance (n=46), receiving a never-functioning graft (n=7), and death-with-a-functioning-graft (n=53) at 101 months after transplant (last-observed-graft loss) were as follows: 9.8%± 2.4%, 10.9%± 1.7%, 1.1%± 0.4%, and 13.0%± 1.9%, respectively. Only three patients experienced GFNC during the first 24 months; GFNC represented 48.1% (26/54) of death-censored GFs beyond 24 months. Two baseline variables were jointly associated with a significantly higher GFNC hazard and cumulative incidence: younger recipient age (P<0.000001 each) and non-white recipient (P=0.004 and P=0.02). Estimated percentages of ever developing GFNC were 28.4%± 6.5% among 79 non-whites younger than 35 years versus 0.0% (0/144) among whites 50 years or older. Among 302 recipients younger than 50 years, 18.1%± 4.1% developed GFNC, representing 67.6% (25/37) of its death-censored graft failures observed beyond 24 months after transplant.

CONCLUSIONS

GFNC is a major cause of late GF at our center, with younger and non-white recipients at a significantly greater GFNC risk. Interventional approaches to eliminate GFNC could dramatically improve long-term kidney graft survival.

Update on the long-term complications of renal transplantation

INTRODUCTION

Powerful immunosuppressive regimens have reduced rejection risk, leading to an expanding cohort of long-term kidney transplant recipients who are likely to encounter practitioners in other specialties.

SOURCES OF DATA

Key review papers and primary literature identified through searches of PubMed, Google Scholar and Medline.

AREAS OF AGREEMENT

Death from cardiovascular disease and malignancy remain the chief causes of transplant loss. Risk factors and phenotypes for these differ from the general population.

AREAS OF CONTROVERSY

Many guidelines for renal transplant recipients are based on extrapolation from studies on non-transplant cohorts and may not be appropriate. Emerging studies demonstrate that established interventions in the general population are less efficacious in transplant recipients.

GROWING POINTS

The influence of immunosuppression on the development of complications.

AREAS TIMELY FOR DEVELOPING RESEARCH

Markers to guide individualized optimal immunosuppression and predict the development of complications would allow for targeted early intervention.

Circulating lymphocyte subsets in different clinical situations after renal transplantation

Phenotypic characterization of T and B lymphocytes allows the discrimination of functionally different subsets. Here, we questioned whether changes in peripheral lymphocyte subset distribution reflect specific clinical and histopathological entities after renal transplantation. Sixty-five renal transplant recipients with either histologically proven (sub)clinical acute rejection or chronic allograft dysfunction, or without abnormalities were studied for their peripheral lymphocyte subset composition and compared with 15 healthy control individuals. Naive, memory and effector CD8(+) T-cell counts were measured by staining for CD27, CD28 and CD45RO/RA. In addition, we studied the CD25(+) CD4(+) T-cell population for its composition regarding regulatory Foxp3(+) CD45RO(+) CD127(-) cells and activated CD45RO(+) CD127(+) cells. Naive, non-switched and switched memory B cells were defined by staining for IgD and CD27. We found a severe decrease in circulating effector-type CD8(+) T cells in recipients with chronic allograft dysfunction at 5 years after transplantation. Percentages of circulating CD25(+) CD127(low) CD4(+) regulatory T cells after transplantation were reduced, but we could not detect any change in the percentage of CD127(+) CD45RO(+) CD4(+) activated T cells in patients at any time or condition after renal transplantation. Regardless of clinical events, all renal transplant recipients showed decreased total B-cell counts and a more differentiated circulating B-cell pool than healthy individuals. The changes in lymphocyte subset distribution probably reflect the chronic antigenic stimulation that occurs in these transplant recipients. To determine the usefulness of lymphocyte subset-typing in clinical practice, large cohort studies are necessary.

Systematic review: kidney transplantation compared with dialysis in clinically relevant outcomes

Individual studies indicate that kidney transplantation is associated with lower mortality and improved quality of life compared with chronic dialysis treatment. We did a systematic review to summarize the benefits of transplantation, aiming to identify characteristics associated with especially large or small relative benefit. Results were not pooled because of expected diversity inherent to observational studies. Risk of bias was assessed using the Downs and Black checklist and items related to time-to-event analysis techniques. MEDLINE and EMBASE were searched up to February 2010. Cohort studies comparing adult chronic dialysis patients with kidney transplantation recipients for clinical outcomes were selected. We identified 110 eligible studies with a total of 1 922 300 participants. Most studies found significantly lower mortality associated with transplantation, and the relative magnitude of the benefit seemed to increase over time (p < 0.001). Most studies also found that the risk of cardiovascular events was significantly reduced among transplant recipients. Quality of life was significantly and substantially better among transplant recipients. Despite increases in the age and comorbidity of contemporary transplant recipients, the relative benefits of transplantation seem to be increasing over time. These findings validate current attempts to increase the number of people worldwide that benefit from kidney transplantation.