Reporting of Rejection after Renal Transplantation in Large Immunosuppressive Trials: Biopsy-Proven, Clinical, Presumed, or Treated Rejection?

Monitoring of blood glucose after pediatric kidney transplantation: a longitudinal cohort study

BACKGROUND

Glucose metabolism after kidney transplantation (KT) is highly dynamic with the first post-transplantation year being the most critical period for new-onset diabetes after transplantation (NODAT) occurrence. The present study aimed to analyze dynamics of glucose metabolism and report incidence/risk factors of abnormal glycemic state during the first year after KT in children.

METHODS

Twenty-one consecutive freshly transplanted pediatric kidney transplant recipients (KTRs) were assessed for fasting plasma glucose (FPG) and oral glucose tolerance test (OGTT) weekly for 4 weeks, then every 3 months for 1 year.

RESULTS

Interpretation of OGTT test showed normal glucose tolerance (NGT) in 6 patients (28.6%) while 15 (71.4%) experienced impaired fasting glucose (IFG) and/or impaired glucose tolerance (IGT) at any time point of monitoring. Seven patients had NODAT, for which three needed insulin therapy. Hyperglycemia onset was 7.8 ± 13.12 weeks (median (range) = 1 (0-24) week) after KT. Percent of patients with abnormal OGTT was significantly more than that of IFG (38.1% vs. 71.4%, p = 0.029). Patients with abnormal glycemic state had significantly elevated trough tacrolimus levels at 6 months (p = 0.03). Glucose readings did not correlate with steroid doses nor rejection episodes while positively correlating with tacrolimus doses at 3 months (p = 0.02, CC = 0.73) and 6 months (p = 0.01, CC = 0.63), and negatively correlating with simultaneous GFR at 9 months (p = 0.04, CC =  - 0.57).

CONCLUSIONS

Up to two thirds of pediatric KTRs (71.4%) experienced abnormal glycemic state at some point with peak incidence within the first week up to 6 months after KT. OGTT was a better tool for monitoring of glucose metabolism than FPG. Abnormal glycemic state was induced by tacrolimus and adversely affected graft function. A higher resolution version of the Graphical abstract is available as Supplementary information.

RtNet: a deep hybrid neural network for the identification of acute rejection and chronic allograft nephropathy after renal transplantation using multiparametric MRI

BACKGROUND

Reliable diagnosis of the cause of renal allograft dysfunction is of clinical importance. The aim of this study is to develop a hybrid deep-learning approach for determining acute rejection (AR), chronic allograft nephropathy (CAN) and renal function in kidney-allografted patients by multimodality integration.

METHODS

Clinical and magnetic resonance imaging (MRI) data of 252 kidney-allografted patients who underwent post-transplantation MRI between December 2014 and November 2019 were retrospectively collected. An end-to-end convolutional neural network, namely RtNet, was designed to discriminate between AR, CAN and stable renal allograft recipient (SR), and secondarily, to predict the impaired renal graft function [estimated glomerular filtration rate (eGFR) ≤50 mL/min/1.73 m2]. Specially, clinical variables and MRI radiomics features were integrated into the RtNet, resulting in a hybrid network (RtNet+). The performance of the conventional radiomics model RtRad, RtNet and RtNet+ was compared to test the effect of multimodality interaction.

RESULTS

Out of 252 patients, AR, CAN and SR was diagnosed in 20/252 (7.9%), 92/252 (36.5%) and 140/252 (55.6%) patients, respectively. Of all MRI sequences, T2-weighted imaging and diffusion-weighted imaging with stretched exponential analysis showed better performance than other sequences. On pairwise comparison of resulting prediction models, RtNet+ produced significantly higher macro-area-under-curve (macro-AUC) (0.733 versus 0.745; P = 0.047) than RtNet in discriminating between AR, CAN and SR. RtNet+ performed similarly to the RtNet (macro-AUC, 0.762 versus 0.756; P > 0.05) in discriminating between eGFR ≤50 mL/min/1.73 m2 and >50 mL/min/1.73 m2. With decision curve analysis, adding RtRad and RtNet to clinical variables resulted in more net benefits in diagnostic performance.

CONCLUSIONS

Our study revealed that the proposed RtNet+ model owned a stable performance in revealing the cause of renal allograft dysfunction, and thus might offer important references for individualized diagnostics and treatment strategy.

Risk Factors for Graft Loss in Pediatric Renal Transplant Recipients After Transfer of Care

BACKGROUND

Improvements in transplantation have increased the survival of children after kidney transplantation. These patients have complex needs, and the current medical system is not prepared to effectively transfer the care of these individuals from pediatric to adult health-care systems. Too often, transfer occurs during moments of crisis and is associated with poor outcomes.

OBJECTIVE

The aim of this study was to use a national database, the Scientific Registry of Transplant Recipients, to test the hypothesis that the increased risk of graft loss after transfer of care (from pediatric to adult services) for young adult kidney transplant recipients over a 2- to 3-year posttransfer follow-up period was related to these posttransfer risk factors (medication noncompliance, acute rejection, insurance status).

DESIGN

A retrospective, longitudinal, correlational design using secondary data was used to evaluate the transfer of care of 250 kidney transplant recipients (ages 16-25).

RESULTS

Seventy-seven (30.8%) individuals lost their graft within 3 years after transfer of care. Medication noncompliance, acute rejection, and serum creatinine >2.0 mg/dL at transfer were significant predictors of graft loss after accounting for multiple other factors.

CONCLUSION

These individuals are at risk for graft loss after transfer of care and may benefit from increased personalized care during this risky period.

Clinical approach to kidney disease in kidney recipients in Spain

BACKGROUND AND OBJECTIVES

In the present study, clinical criteria used by Spanish nephrologists when approaching chronic kidney disease (CKD) in kidney recipients, as well as their level of maintenance and control of renal function, were evaluated.

METHODS

An epidemiological, observational, multicenter, nation-wide, prospective study was carried out, with a 6-month follow-up period. Three hundred and sixty-eight adult patients with stage3 kidney disease after a 24-month or longer post-transplantation follow-up period were included. Visits schedule included a retrospective visit, a baseline visit, an optional mid-term visit, and a final visit at month6.

RESULTS

Mean time since kidney transplantation was 8.2±5.4years. Most common pre-transplant cardiovascular risk factors were high blood pressure (80.2%), followed by high cholesterol levels (61.7%). Serum creatinine levels showed a statistically significant decrease from baseline visit to 6-month visit (0.06±0.22; P<.0001), and glomerular filtration rate (GFR) reduction was -1.03±6.14 (P=0.0014). Significant independent prognostic factors for GFR worsening were: higher 24-hour proteinuria (OR=1.001 per mg; P=.020), longer time since transplantation (OR=1.009 per month; P=.017), and lower hemoglobin levels (OR=1.261 per g/dl; P=.038). Donor age also had some negative influence (OR=1.021 per year; P=.106). Biopsies were obtained in only 8% of kidney transplant recipients with stage 3 CKD with an intervention being carried out in 25.4% of cases.

CONCLUSIONS

Secondary markers and factors resulting in CKD progression, particularly anemia, are still frequently uncontrolled after kidney transplantation. Only about 2% of patients benefit from a therapeutic intervention based on a biopsy. Clinical perception differs from objective measures, which results in an obvious clinical inertia regarding risk factor control in such patients.

Consistency and completeness of reported outcomes in randomized trials of primary immunosuppression in kidney transplantation

Inconsistent and incomplete outcome reporting may make estimates of treatment effects from published randomized trials unreliable. We aimed to determine outcome reporting practices and source of differences in reporting quality among randomized trials of primary immunosuppression in kidney transplantation. We searched the Cochrane Renal Group's Specialized Register, 2000-2012, specified four core outcomes we expected trials to report, and recorded if and how completely each was reported. We identified 179 trials. One hundred sixty-eight (94%) reported death, 145 (81%) as number dead and 119 (66%) as time to death. One hundred sixty-five (92%) reported graft loss, 158 (88%) as number with graft loss and 127 (71%) as time to graft loss. One hundred twenty-one (68%) reported creatinine and 114 (64%) estimated GFR (eGFR). One hundred forty-one (79%) provided complete reports of number dead, 95 (53%) censored and 99 (55%) uncensored number with graft loss. Seventy-three (41%) provided complete reports of time to death, 67 (37%) censored and 31 (17%) uncensored time to graft loss. Complete reporting of graft function was infrequent: 62 (35%) eGFR and 50 (28%) creatinine. All four outcomes were reported in any form in 61 (34%) and completely in 28 (16%) trials. No single trial or journal characteristic was consistently associated with complete outcome reporting. Outcome reporting in kidney transplant trials is inconsistent and frequently incomplete, and published estimates of treatment effects may be unreliable.

Why rejections are not biopsy proven: frequency and reasons

BACKGROUND

Rejection still has a fundamental impact on patient and graft survivals after renal transplantation. Published studies vary widely in their reporting of biopsy-proven acute rejection (BPAR) and non-BPAR rates. We undertook a systematic search of existing publications for reasons explaining this difference. Additionally, we analyzed our own population, which has a clearly defined biopsy strategy, to further investigate the rate of non-BPAR in routine clinical practice.

METHODS

From large, multicenter, randomized, controlled trials investigating immunosuppressive regimens in de novo kidney transplant recipients, we extracted the rates of all reported rejections ("total" rate) versus BPAR. Non-BPAR was defined as the difference between "total" and BPAR. Additional analyses were performed for potential influencing factors, such as year of publication, number, and mean age of patients recruited and impact factor of the journal at the time of publication. We scanned all de novo adult patients undergoing kidney transplantation in our center between 1996 and 2004 for rejection episodes during the first year.

RESULTS

The median rate of non-BPAR within the first year in 27 papers was 7% (range, 0%- 16.9%). Similarly, the relative proportion of non-BPAR showed large differences. We could not identify potential influencing factors to explain the large variability. Among our population, 136/365 patients (37.3%) experienced acute rejection episodes, with BPAR diagnosed in 90/365 patients (24.7%), yielding an absolute 12.6% rate of non-BPAR.

CONCLUSION

Even centers with a well-defined biopsy strategy show a substantial proportion of non-BPAR episodes. Therefore, complete reporting of both BPAR and non-BPAR is important for the proper interpretation of study results.

Clinical assessment and determinants of chronic allograft nephropathy in maintenance renal transplant patients

BACKGROUND

Current knowledge about the natural history, treatment and physicians' perception of chronic allograft nephropathy (CAN) is limited. The present study evaluated the prevalence and determinants of CAN in renal transplant patients.

METHODS

Epidemiological, cross-sectional multi-centre study conducted in Spain. A total of 872 renal transplant recipients with a functioning graft and at least 2 years of post-transplant data on renal function were consecutively included. CAN diagnosis was recorded based on physician's clinical criteria and on laboratory criteria (serum creatinine ≥ 2 mg/dL and/or glomerular filtration rate ≤ 50 mL/min).

RESULTS

The mean time from transplantation until the time of this study was 8.2 years. CAN was diagnosed in 35% of patients (n = 305) according to the physician's criteria (31% of whom with histological assessment) and in 55.5% (n = 482) according to laboratory objective criteria. An older donor age, lack of induction therapy, cyclosporine use, lower tacrolimus levels at 1 year, acute rejection, hypertension and worse initial renal function were associated with CAN development. Time from transplant to biopsy was greater in patients with anti-proteinuric treatment. Immunosuppression was modified in 46.9% of patients with CAN diagnosis [calcineurin inhibitor (CNI) reduction alone in 18.9% of cases; CNI reduction and mycophenolate modification in 17.8% and CNI reduction or withdrawal with introduction of proliferation signal inhibitors in 12.9%).

CONCLUSIONS

After ~8 years from renal transplantation, 55.5% of patients presented CAN, which was considerably underestimated by physicians. An older donor age and less initial immunosuppression seemed to be related to CAN development.

Feasibility of diagnosing renal allograft dysfunction by oligonucleotide array: Gene expression profile correlates with histopathology

BACKGROUND

Effective non-invasive monitoring method to tell histopathology is a big challenge in renal transplantation.

METHODS

We used 70-mer long oligonucleotide array with 449 immune related genes to determine gene expression profiles of peripheral blood mononuclear cells (PBMCs) under different immune status including stable renal function (TX), acute tubular necrosis (ATN), biopsy conformed acute rejection (AR), clinical rejection with pathology of borderline changes (BL), clinical rejection without biopsy proven/presumed rejection (PR) and renal dysfunction without rejection (NR).

RESULTS

Distinct molecular expression signatures in each group were found to correlate with histopathology. And we concluded that B cell chemokine CXCL13 and mast cell may play a role in renal allograft rejection through significant difference analysis and functional pathway analysis.

CONCLUSIONS

It provides a potential non-invasive method for monitoring renal allograft function and immune status of renal transplant recipients.