Impact of slow and delayed graft function on kidney graft survival between various subgroups among renal transplant patients

Impact of hyperparathyroidism on allograft histology and function after kidney transplantation: Rethinking its causal role in graft dysfunction

INTRODUCTION

The causal relationship between hyperparathyroidism and kidney graft dysfunction remains inconclusive. Applying Bradford-Hill's temporality and consistency causation principles, we assessed the effect of parathyroid hormone (iPTH) on graft histology and eGFR trajectory on kidney transplant recipients (KTRs) with normal time-zero graft biopsies.

METHODS

Retrospective cohort study evaluating the effect of hyperparathyroidism on interstitial fibrosis and tubular atrophy (IF/TA) development in 1232 graft biopsies. Pre-transplant hyperparathyroidism was categorized by KDIGO or KDOQI criteria, and post-transplant hyperparathyroidism by iPTH >1× and >2× the URL 1 year after transplantation.

RESULTS

We included 325 KTRs (56% female, age 38 ± 13 years, follow-up 4.2 years [IQR: 2.7-5.8]). Based on pre-transplant iPTH levels, 26% and 66% exceeded the KDIGO and KDOQI targets, respectively. There were no significant differences in the development of >25% IF/TA between KTRs with pre-transplant iPTH levels above and within target range according to KDIGO (53% vs. 62%, P = .16, HR.94 [95% CI:.67-1.32]) and KDOQI (60% vs. 60%, P = 1.0, HR 1.19 [95% CI:.88-1.60]) criteria. Similarly, there were no differences when using 1 year post-transplant iPTH cut-offs > 88 pg/mL (58% vs. 64%, P = .33) and > 176 pg/mL (55% vs. 62%, P = .19). After adjusting for confounders, no significant differences were observed in eGFR trajectories among the iPTH strata.

CONCLUSION

In young KTRs who received a healthy graft, no association was found between increased pre- and post-transplant iPTH levels and graft dysfunction, as assessed histologically and through eGFR trajectory. The concept of hyperparathyroidism as a risk factor for graft dysfunction in recipients at low risk requires reevaluation.

An analysis of the relationship between donor and recipient biomarkers and kidney graft function, dysfunction, and rejection

BACKGROUND

The study aimed to find predictive biomarkers to evaluate donor kidney function to predict graft dysfunction as well as to assess an early signs of acute graft rejection.

METHOD

Twenty-seven deceased donors and 54 recipients who underwent a successful kidney transplantation were enrolled in the study. An assessment was made in serum and urine from donors and recipients to measure the following biomarkers: neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), tissue inhibitor of metalloproteinase 2 (TIMP-2) and urinary N-acetyl-b-D-glucosaminidase (uNAG). These biomarkers were used to establish a model for predicting a reduced graft function (RGF) classified as either a delayed or slow graft function.

RESULT

Our analysis suggest that out of four tested biomarkers, the serum TIMP-2 and uNAG levels of the donors had a predictive value for RGF; the area under the receiver operating characteristic curves (AUROC) of serum TIMP-2 and uNAG were 0.714 and 0.779, respectively. The combined best fitting prediction model of serum TIMP-2, uNAG, and creatinine levels was better in predicting RGF than the serum creatinine level alone. In addition, the recipient serum TIMP-2 level on the third day post-transplantation (D3) was associated with the estimated glomerular filtration rate (eGFR) on the seventh day post-transplantation (D7; OR 1.119, 95% CI 1.016-1.233, p = 0.022). Furthermore, the ROC curve value revealed that the AUROC of TIMP-2 on D3 was 0.99 (95% CI 0.97-1, p < 0.001), and this was the best predictive value of the renal function on D7.

CONCLUSIONS

Donor serum TIMP-2 and uNAG levels are useful predictive biomarkers because they can provide the donor-based prediction for RGF.

The Impact of Intraoperative Graft Blood Flow Measurement on Early Graft Function

BACKGROUND

The aim of this study is to evaluate the impact of intraoperative allograft vascular flow on early kidney graft function.

METHODS

A total of 159 patients underwent kidney transplantation from January 2017 to March 2022 at Linkou Chang Gung Memorial Hospital. Graft arterial and venous blood flow was measured separately with a transient time flowmeter (Transonic HT353; Transonic Systems, Inc, Ithaca, NY, United States) after ureteroneocystostomy. The early outcomes, including the postoperative creatinine level, were analyzed accordingly.

RESULTS

There were 83 males and 76 females, with a mean age of 44.5 years. The mean graft arterial flow measured was 480.6 mL/min, and the mean venous flow was 506.2 mL/min. Delayed graft function (DGF) incidence was 36.5%, 32.5%, and 40.8% in total, living, and deceased donor groups, respectively. Living donor and deceased donor kidney transplantation were analyzed separately. In the DGF subgroup, there were lower graft venous flows, higher body mass index (BMI), and more male patients in the living kidney transplant group. Similarly, the deceased donor kidney transplantation group with delayed graft function tended to have higher body height, higher body weight, higher BMI, and more diabetes mellitus. The multivariate analysis showed that lower graft venous blood flow (odds ratio [OR] = 0.995, P = .008) and higher BMI (OR = 1.144, P = .042) were significantly correlated with delayed graft function in living donor kidney transplantations. In the deceased donor group, a multivariate analysis of risk factors showed that BMI had a significant correlation with delayed graft function (OR = 1.41, P = .039).

CONCLUSIONS

Graft venous blood flow was significantly associated with delayed graft function in living donor kidney transplantation, and high BMI was correlated with DGF in all patients receiving kidney transplantation.

Complement Blockade in Recipients Prevents Delayed Graft Function and Delays Antibody-mediated Rejection in a Nonhuman Primate Model of Kidney Transplantation

BACKGROUND

Complement activation in kidney transplantation is implicated in the pathogenesis of delayed graft function (DGF). This study evaluated the therapeutic efficacy of high-dose recombinant human C1 esterase inhibitor (rhC1INH) to prevent DGF in a nonhuman primate model of kidney transplantation after brain death and prolonged cold ischemia.

METHODS

Brain death donors underwent 20 h of conventional management. Procured kidneys were stored on ice for 44-48 h, then transplanted into ABO-compatible major histocompatibility complex-mismatched recipients. Recipients were treated with vehicle (n = 5) or rhC1INH 500 U/kg plus heparin 40 U/kg (n = 8) before reperfusion, 12 h, and 24 h posttransplant. Recipients were followed up for 120 d.

RESULTS

Of vehicle-treated recipients, 80% (4 of 5) developed DGF versus 12.5% (1 of 8) rhC1INH-treated recipients (P = 0.015). rhC1INH-treated recipients had faster creatinine recovery, superior urinary output, and reduced urinary neutrophil gelatinase-associated lipocalin and tissue inhibitor of metalloproteinases 2-insulin-like growth factor-binding protein 7 throughout the first week, indicating reduced allograft injury. Treated recipients presented lower postreperfusion plasma interleukin (IL)-6, IL-8, tumor necrosis factor-alpha, and IL-18, lower day 4 monocyte chemoattractant protein 1, and trended toward lower C5. Treated recipients exhibited less C3b/C5b-9 deposition on day 7 biopsies. rhC1INH-treated animals also trended toward prolonged mediated rejection-free survival.

CONCLUSIONS

Our results recommend high-dose C1INH complement blockade in transplant recipients as an effective strategy to reduce kidney injury and inflammation, prevent DGF, delay antibody-mediated rejection development, and improve transplant outcomes.

Creatinine reduction ratio on postoperative day 2 predicts long-term outcomes after living donor kidney transplantation

OBJECTIVES

To evaluate the relationship between the creatinine reduction ratio between postoperative days 1 and 2 and post-transplantation clinical outcomes after living donor kidney transplantation.

METHODS

Clinical data of patients who underwent living donor kidney transplantation at Jichi Medical University Hospital, Tochigi, Japan, between 2006 and 2019 were retrieved. The creatinine reduction ratio between postoperative days 1 and 2 was calculated based on the formula: (Cre1 - Cre2) × 100/Cre1; patients were then classified into either the slow graft function (creatinine reduction ratio between postoperative days 1 and 2 ≤30%) or immediate graft function (creatinine reduction ratio between postoperative days 1 and 2 >30%) group. We carried out the log-rank test and multivariate Cox proportional hazards regression analyses to assess graft survival and rejection-free survival, and the unpaired t-test and multivariate linear regression to assess post-transplantation estimated glomerular filtration rates. Multivariate analyses used age, sex, dialysis duration, ABO compatibility, donor-specific antibody positivity and medically complex living donors as explanatory variables.

RESULTS

Of the 272 patients, 30 and 242 were in the slow graft function and immediate graft function groups, respectively. Multivariate Cox proportional hazards regression analyses showed a significantly higher incidence of overall and death-censored graft loss in the slow graft function group than the immediate graft function group. The frequency of rejection after 1 week post-transplantation did not differ within the groups. Post-transplantation estimated glomerular filtration rates tended to decline earlier in the slow graft function group than in the immediate graft function group; however, the difference was not statistically significant.

CONCLUSIONS

The creatinine reduction ratio between postoperative days 1 and 2 could potentially predict long-term outcomes after living donor kidney transplantation. Using the creatinine reduction ratio between postoperative days 1 and 2 and other conventional indicators might allow accurate risk classification and appropriate therapeutic interventions.

Intraoperative Near-Infrared Spectroscopy Monitoring of Renal Allograft Reperfusion in Kidney Transplant Recipients: A Feasibility and Proof-of-Concept Study

Conventional renal function markers are unable to measure renal allograft perfusion intraoperatively, leading to delayed recognition of initial allograft function. A handheld near-infrared spectroscopy (NIRS) device that can provide real-time assessment of renal allograft perfusion by quantifying regional tissue oxygen saturation levels (rSO₂) was approved by the FDA. This pilot study evaluated the feasibility of intraoperative NIRS monitoring of allograft reperfusion in renal transplant recipients (RTR). Intraoperative renal allograft rSO₂ and perfusion rates were measured in living (LDRT, n = 3) and deceased donor RTR (DDRT, n = 4) during the first 50 min post-reperfusion and correlated with renal function markers 30 days post-transplantation. Intraoperative renal allograft rSO₂ for the DDRT group remained significantly lower than the LDRT group throughout the 50 min. Reperfusion rates were significantly faster in the LDRT group during the first 5 min post-reperfusion but remained stable thereafter in both groups. Intraoperative rSO₂ were similar among the upper pole, renal hilum, and lower pole, and strongly correlated with allograft function and hemodynamic parameters up to 14 days post-transplantation. NIRS successfully detected differences in intraoperative renal allograft rSO₂, warranting future studies to evaluate it as an objective method to measure ischemic injury and perfusion for the optimization of preservation/reperfusion protocols and early prediction of allograft function.

ABO Blood Incompatibility Positively Affects Early Graft Function: Single-Center Retrospective Cohort Study

BACKGROUND

We investigated the association between ABO-incompatible (ABO-I) kidney transplantation and early graft function.

METHODS

We retrospectively analyzed 95 patients who underwent living donor kidney transplantation between May 2009 and July 2019. It included 61 ABO-compatible (ABO-C) and 34 ABO-I transplantations. We extracted data on immunologic profile, sex, age, cold ischemic time, type of immunosuppression, and graft function. Two definitions were used for slow graft function (SGF) as follows: postoperative day (POD) 3 serum creatinine level >3 mg/dL and estimated glomerular filtration rate (eGFR) <20 mL/min/1.73 m². Logistic regression analysis was performed to analyze the effect of ABO-I on the incidence of SGF.

RESULTS

The characteristics between the ABO-C and ABO-I were not different. ABO-I received rituximab and plasma exchange. Patients also received tacrolimus and mycophenolate mofetil for 2 weeks and prednisolone for 1 week before transplantation as preconditioning. Of the 95 study patients, 19 (20%) and 21 (22%) were identified with SGF according to POD 3 serum creatinine level or eGFR, respectively. Multivariable analysis revealed that ABO-I significantly reduced the incidence of SGF (odds ratio, 0.15; 95% confidence interval, 0.03-0.7; P = .02), and cold ischemic time >150 min increased the incidence of SGF (odds ratio, 6.5; 95% confidence interval, 1.7-25; P = .006). Similar results were identified in POD 3 eGFR. Inferior graft function in patients with SGF was identified up to 6 months after transplantation.

CONCLUSION

ABO-I reduces the incidence of SGF, which is associated with an inferior graft function up to 6 months.

Kinetic GFR Outperforms CKD-EPI for Slow Graft Function Prediction in the Immediate Postoperative Period Following Kidney Transplantation

Background: Rapid identification of patients at high risk for slow graft function (SGF) is of major importance in the immediate period following renal graft transplantation, both for early therapeutic decisions and long-term prognosis. Due to the high variability of serum creatinine levels after surgery, glomerular filtration rate (GFR) estimation is challenging. In this situation, kinetic estimated GFR (KeGFR) equations are interesting tools but have never been assessed for the identification of SGF patients. Methods: We conducted a single-center retrospective cohort study, including all consecutive kidney allograft recipients in the University Hospitals of Geneva from 2008 to 2016. GFR was estimated using both CKD-EPI and KeGFR formulae. Their accuracies for SGF prediction were compared. Patients were followed up for one year after transplantation. Results: A total of 326 kidney recipients were analyzed. SGF occurred in 76 (23%) patients. KeGFR estimation stabilized from the day following kidney transplantation, more rapidly than CKD-EPI. Discrimination ability for SGF prediction was better for KeGFR than CKD-EPI (AUC 0.82 and 0.66, p < 0.001, respectively). Conclusion: KeGFR computed from the first day after renal transplantation was able to predict SGF with good discrimination, outperforming CKD-EPI estimation. SGF patients had lower renal graft function overall at the one-year follow up.

Donor Plasma Mitochondrial DNA Is Correlated with Posttransplant Renal Allograft Function

BACKGROUND

The lack of accurate biomarkers makes it difficult to determine whether organs are suitable for transplantation. Mitochondrial DNA (mtDNA) correlates with tissue damage and kidney disease, making it a potential biomarker in organ evaluation.

METHODS

Donors who had experienced cardiac death and successfully donated their kidneys between January 2015 and May 2017 were included this study. We detected the level of mtDNA in the plasma of the donor using quantitative real-time polymerase chain reaction and then statistically analyzed the relationship between the level of mtDNA and the delayed graft function (DGF) of the recipient.

RESULTS

The incidence of DGF or slowed graft function (SGF) increased by 4 times (68% versus 16%, P < 0.001) when the donor mtDNA (dmtDNA) level was >0.114. When dmtDNA levels were >0.243, DGF and primary nonfunction were approximately 100% and 44%, respectively. Moreover, dmtDNA was an independent risk factor for slowed graft function and DGF. A prediction model for DGF based on dmtDNA achieved an area under the receiver operating characteristic curve for a prediction score as high as 0.930 (95% confidence interval 0.856-1.000), and the validation cohort results showed that the sensitivity and specificity of the model were 100% and 78%, respectively. dmtDNA levels were correlated with 6-month allograft function (R=0.332, P < 0.001) and 1-year graft survival (79% versus 99%, P < 0.001).

CONCLUSIONS

We conclusively demonstrated that plasma dmtDNA was an independent risk factor for DGF, which is valuable in organ evaluation. dmtDNA is a possible first predictive marker for primary nonfunction and worth further evaluation.

SLPI in the perfusion solution helps to identify graft quality in kidney transplants

Aim: It is important to find biomarkers that identify the graft quality in kidney transplantation. Results & methodology: The level of SLPI in the cold preservation solution was used as a marker to predict early kidney graft function after transplantation. Before transplantation, kidneys were washed and SLPI was measured in the discarded solution. A retrospective analysis showed that patients with delayed graft function or rejection episodes in post-trasplant, had higher SLPI concentrations in the perfusion solution than patients without delayed graft function or rejections. Furthermore, SLPI could discriminate between patients with better or worse estimated glomerular filtration rate among low-risk patients (kidney donor profile index <80). Discussion & conclusion: These results suggest that the SLPI concentration in the perfusion solutions could be a predictor of short-term organ function and a complement to the kidney donor profile index score.

The impact of kidney donor profile index on delayed graft function and transplant outcomes: A single-center analysis

INTRODUCTION

Renal transplant outcomes result from a combination of factors. Traditionally, donor factors were summarized by classifying kidneys as extended criteria or standard criteria. In 2014, the nomenclature changed to describe donor factors with the kidney donor profile index (KDPI). We aim to evaluate the relationship between KDPI and delayed graft function (DGF), and the impact KDPI on transplant outcomes for both donor after cardiac death (DCD) and donor after brain death (DBD).

METHODS

An IRB-approved single-center retrospective chart review was performed from January 1999 to July 2013. The patients were divided into six groups: DBD KDPI ≤60, DBD KPDI 61-84, DBD KDPI ≥85, DCD KDPI ≤60, DCD KPDI 61-84, and DCD KDPI ≥85. Rates of DGF, patient survival, and graft survival were examined among groups.

RESULTS

A total of 2161 kidney transplants were included. DGF rates increased, and graft and patient survival decreased with increasing KDPI (P < .001). DCD kidneys had higher DGF rates than their DBD counterparts (P < .001). In DCD kidneys, a higher KDPI score did not significantly affect the DGF rates (P > .302). There was no significant difference in graft or patient survival in all-comers when comparing DCD and DBD kidneys with equivalent KDPIs (P > .317). Patients with DGF across all categories demonstrated worse graft half-lives.

CONCLUSION

The KDPI system is an accurate predictor of donor contributions to transplant outcomes. Recipients of DBD kidneys experience an increase in the rate of DGF as their KDPI increases. DCD kidneys have higher DGF rates than their DBD counterparts with similar KDPIs. Patients with documented post-transplant DGF had between 3- and 5-year shorter graft half-lives when compared to recipients that did not experience DGF. Initiatives to reduce the rate of DGF could provide a significant impact on graft survival and result in a reduction in the number of patients requiring retransplant.

Nonimmunologic Factors Affecting Long-Term Outcomes of Deceased-Donor Kidney Transplant

OBJECTIVES

We investigated the impact of nonimmuno-logic factors on patient and graft survival after deceased-donor kidney transplant.

MATERIALS AND METHODS

All deceased-donor kidney transplants performed between January 2004 and December 2015 were included in our analyses. We used the independent t test to calculate significant differences between means above and below medians of various parameters.

RESULTS

All study patients (N = 205; 58.7% males) received antithymocyte globulin as induction therapy and standard maintenance therapy. Patients were free from infection, malignancy, and cardiac, liver, and pulmonary system abnormalities. Most patients (89.2%) were recipients of a first graft. Median patient age, weight, and cold ischemia time were 38 years, 65 kg, and 15 hours, respectively. Delayed graft function, diabetes mellitus, and hypertension occurred in 19.1%, 43.4%, and 77.9% of patients, respectively. The 1- and 5-year graft survival rates were 95% and 73.8%. Graft survival was not affected by donor or recipient sex or recipient diabetes or hypertension. However, graft survival was longer in patients who received no graft biopsy (8.2 vs 6.9 y; P = .027) and in those who had diagnosis of calcineurin inhibitor nephrotoxicity versus antibody-mediated rejection after biopsy (8.19 vs 3.66 y; P = .0047). Longer survival was shown with donors who had traumatic death versus cerebro-vascular accident (5.9 vs 5.3 y; P = .029) and donors below the 50th percentile in age (8.23 and 7.14 y; P = .0026) but less with donors who had terminal acute kidney injury (6.97 vs 8.16 y; P = .0062). We found a negative correlation between graft survival and donor age (P = .01) and 1-year serum creatinine (P = .01).

CONCLUSIONS

Donor age, cause of brain death, and acute kidney injury affected graft survival in our study cohort but not donor or recipient sex or posttransplant or donor blood pressure.

Influence of pretransplant midodrine use on outcomes after kidney transplantation

Evaluation of potential kidney transplant recipients is important to identify and treat conditions that may influence graft or patient survival after transplantation. We performed a single-center, observational cohort study to determine whether pretransplant midodrine use influences outcomes after kidney transplantation. We analyzed graft and patient outcomes for adult patients who underwent a kidney-only transplantation at Barnes-Jewish Hospital from January 1999 to December 2015. We quantified adjusted associations of pretransplant midodrine use with post-transplant complications by multivariable Cox regression. Among the 2621 kidney transplant recipients analyzed, 37 (1.4%) were taking midodrine immediately prior to transplantation. Midodrine users were more commonly older (56.5 vs 50.4 years) and obese (67.6% vs 33.6%). Midodrine users were also more likely to be on hemodialysis (86.5% vs 59.2%), to have a longer duration of dialysis dependence (646 months vs 577 months), and to have higher levels of sensitization (peak panel reactive antibody >20%, 32.4% vs 15.8%) compared to nonusers. Pretransplant midodrine users had significantly higher rates of delayed graft function (DGF) (32.4% vs 6.7%, P < 0.001). No difference in the incidence of DGF was observed based on the midodrine dosing regimen. After multivariable adjustment for recipient and donor characteristics, pretransplant midodrine use was independently associated with graft failure at 1 year (adjusted hazard ratio, 5.11; 95% confidence interval, 2.09-12.49).

Association of Slow Graft Function with Long-Term Outcomes in Kidney Transplant Recipients

Background

Whether slow graft function (SGF) represents an intermediate phenotype between immediate graft function (IGF) and delayed graft function (DGF) in kidney transplant recipients is unknown.

Material/Methods

In a retrospective cohort analysis of 1,222 kidney transplant recipients, we classified patients as having IGF, SGF, and DGF using two different schemas. SGF was defined as serum creatinine (Cr) ≥3.0 mg/dL by postoperative day 5 in Schema 1, and in Schema 2, SGF was defined as Cr >1.5 mg/dL plus a creatinine reduction ratio <20% between postoperative days 1 and 3. A complementary log-log model was used to examine the association of graft function with graft survival and patient survival.

Results

Mean age of study patients was 51.5±13.3 years, 59.9% were male, and 66.7% were white. In Schema 1, SGF and DGF were associated with comparable increases in risk of graft failure compared to IGF (hazard ratio (HR) 1.46, 95% confidence intervals (CI) 1.02–2.10 for SGF and HR 1.56, CI 1.11–2.22 for IGF); estimates were similar for Schema 2 (HR 1.52, CI 1.05–2.20 for SGF and HR 1.54, CI 1.10–2.17 for IGF). However, for mortality, outcomes for SGF were similarly to IGF, both SGF and IGF were associated with lower risk relative to DGF (HR 0.54, CI 0.36–0.80 for SGF in Schema 1; HR 0.58, CI 0.39–0.85 for SGF in Schema 2).

Conclusions

These findings suggest that SGF may be a marker for graft failure but not for mortality, and SGF may therefore represent a phenotype separate from IGF and DGF.

Delayed Graft Function Phenotypes and 12-Month Kidney Transplant Outcomes

BACKGROUND

Ischemia-reperfusion injury (IRI) leading to delayed graft function (DGF), defined by the United Network for Organ Sharing as dialysis in the first week (UNOS-DGF), associates with poor kidney transplant outcomes. Controversies remain, however, about dialysis initiation thresholds and the utility for other criteria to denote less severe IRI, or slow graft function (SGF).

METHODS

Multicenter, prospective study of deceased-donor kidney recipients to compare UNOS-DGF to a definition that combines impaired creatinine reduction in the first 48 hours or greater than 1 dialysis session for predicting 12-month estimated glomerular filtration rate (eGFR). We also assessed 10 creatinine and urine output-based SGF definitions relative to 12-month eGFR.

RESULTS

In 560 recipients, 215 (38%) had UNOS-DGF, 330 (59%) met the combined definition, 14 (3%) died, and 23 (4%) had death-censored graft failure by 12 months. Both DGF definitions were associated with lower adjusted 12-month eGFR (95% confidence interval)-by 7.3 (3.6-10.9) and 7.4 (3.8-11.0) mL/min per 1.73 m, respectively. Adjusted relative risks for 12-month eGFR less than 30 mL/min per 1.73 m were 1.9 (1.2-3.1) and 2.1 (1.1-3.7), with unadjusted areas under the curve of 0.618 and 0.627, respectively. For SGF definitions, postoperative day (POD) 7 creatinine had the strongest association with 12-month eGFR, and POD5 creatinine and creatinine reduction between POD1 and POD2 demonstrated modest separations in 12-month eGFR.

CONCLUSIONS

Although UNOS-DGF does not adequately predict 12-month function on its own, our findings do not support changing the definition. Postoperative day 7 creatinine is correlated with 12-month eGFR, but large translational studies are needed to understand the biological link between IRI severity at transplant and longer-term outcomes.

An Improved Classification of Kidney Function Recovery Using Estimated Glomerular Filtration Rate Slope Post-transplantation

BACKGROUND

The impact of renal function recovery on graft survival was examined using estimated glomerular filtration rate (eGFR) slope after kidney transplantation (GAP classification); this was compared to the conventional classification of immediate graft function (IGF), slow graft function (SGF), and delayed graft function (DGF).

MATERIALS AND METHODS

Overall, 541 cases of cadaveric renal transplants were reviewed from a prospective transplant database. eGFR and its slope were measured using the harmonic mean over the first week post-transplantation. Next, 495 kidney transplant recipients from an independent institution were assessed to determine the prognostic value of graft function based on the eGFR slope.

RESULTS

The main discrimination of eGFR slopes occurred within the first 7 days. Three groups in the GAP classification (Good graft function, Average graft function, Poor graft function) were defined based on eGFR slope tertiles: good graft function (GGF), average graft function (AGF), and poor graft function (PGF) were defined based on the ΔCrCL per day over the first 7 days: <1 mL/min, 1-4 mL/min, and >4 mL/min, respectively. When applied to the validation cohort, the 5-year graft failure was 20% for the PGF group, 4% for the AGF group, and 3% for the GGF group. Multivariable Cox regression analysis demonstrated better prediction of long-term graft function with the new classification (C statistic 0.49 [old)] vs 0.61 [new]).

CONCLUSION

The new GAP criteria were better at predicting long-term graft survival and renal function compared to the conventional classification system, and deserve further consideration in future studies.

The effect of pre-operative methylprednisolone on the incidence of delayed graft function in renal transplantation

Introduction:

This study explores the effect of different corticosteroid administration timings on the incidence of slow/delayed graft function.

Methods:

One hundred and twelve kidney transplants from January 2011 to March 2014 were retrospectively analysed. Thirty-six cases were excluded because they were donor-specific antibody positive ( n=16), received thymoglobulin/plasma exchange ( n=11), were ABO-incompatible ( n=6) or suffered graft loss from vascular thrombosis within the first week post-transplant ( n=3). The study period straddled three eras of corticosteroid administration, from intra-operative intravenous (IV) hydrocortisone (Era 1; n=26), to intra-operative IV methylprednisolone (Era 2; n=38) and pre-operative IV methylprednisolone (Era 3; n=12). The primary endpoint was the incidence of slow/delayed graft function. Secondary outcomes included estimated glomerular filtration rate at discharge and 120 and 365 days, rejection (acute and one-year), wound complications, post-transplant diabetes, increase in low-density lipoprotein or body mass index, and cytomegalovirus or BK viraemia within one year.

Results:

On univariate analysis, pre-operative methylprednisolone was associated with lower incidence of slow/delayed graft function (17%, 55%, 58% in Eras 3, 2, 1 respectively; p=0.041), superior estimated glomerular filtration rate at discharge (median 56, 37 and 43 ml/min for Eras 3, 2, 1 respectively; p=0.033) and at 120 days (median 60, 52, and 46 ml/min for Eras 3, 2, 1 respectively; p=0.017). On multivariate analysis, pre-operative IV methylprednisolone ( vs. Eras 1 and 2 combined; odds ratio 4.79 (90% confidence interval 1.16–19.80); p=0.07) and living donor type ( vs. deceased; odds ratio 5.56 (90% confidence interval 2.25–13.77); p=0.002) were associated with lower incidence of slow/delayed graft function.

Conclusion:

Pre-operative methylprednisolone was associated with reduced slow/delayed graft function and improved early estimated glomerular filtration.

Using an Integrated -Omics Approach to Identify Key Cellular Processes That Are Disturbed in the Kidney After Brain Death

In an era where we are becoming more reliant on vulnerable kidneys for transplantation from older donors, there is an urgent need to understand how brain death leads to kidney dysfunction and, hence, how this can be prevented. Using a rodent model of hemorrhagic stroke and next-generation proteomic and metabolomic technologies, we aimed to delineate which key cellular processes are perturbed in the kidney after brain death. Pathway analysis of the proteomic signature of kidneys from brain-dead donors revealed large-scale changes in mitochondrial proteins that were associated with altered mitochondrial activity and morphological evidence of mitochondrial injury. We identified an increase in a number of glycolytic proteins and lactate production, suggesting a shift toward anaerobic metabolism. Higher amounts of succinate were found in the brain death group, in conjunction with increased markers of oxidative stress. We characterized the responsiveness of hypoxia inducible factors and found this correlated with post-brain death mean arterial pressures. Brain death leads to metabolic disturbances in the kidney and alterations in mitochondrial function and reactive oxygen species generation. This metabolic disturbance and alteration in mitochondrial function may lead to further cellular injury. Conditioning the brain-dead organ donor by altering metabolism could be a novel approach to ameliorate this brain death-induced kidney injury.

A new method of modelling early plasma creatinine changes predicts 1-year graft function after kidney transplantation

BACKGROUND

Delayed graft function after renal transplantation is associated with inferior long-term outcome. To evaluate the impact of slow onset graft function, we aimed to model and correlate early changes in plasma creatinine (p-cr) with long-term graft function.

MATERIALS

In a single centre observational study of 100 kidney transplants we identified all p-cr measurements from the time of transplantation until 30 days post-transplant or last post-transplant dialysis, and correlated this with estimated glomerular filtration rate (eGFR) 1 year after transplantation. The initial changes in p-cr were modelled for each patient using an exponential, logistic, or linear model, and the time to a 50% decrease in p-cr (tCr50) was estimated.

RESULTS

Linear regression analysis showed a negative correlation between tCr50 and eGFR 1 year post-transplant (n = 96, r = -0.369, β = -0.112, p = 0.0002). The correlation was maintained when corrected for the relevant recipient and donor characteristics. tCr50 correlated positively with the number of hospitalisation days, the number of graft ultrasound examinations, and the number of biopsies.

CONCLUSIONS

A modelled time to a 50% decrease in p-cr predicts 1-year graft function. tCr50 may be a relevant surrogate endpoint in renal transplant studies aimed at improving long-term function by reducing the incidence of slow onset graft function.

Pre-transplant Evaluation of Donor Urinary Biomarkers can Predict Reduced Graft Function After Deceased Donor Kidney Transplantation

Several recipient biomarkers are reported to predict graft dysfunction, but these are not useful in decision making for the acceptance or allocation of deceased donor kidneys; thus, it is necessary to develop donor biomarkers predictive of graft dysfunction. To address this issue, we prospectively enrolled 94 deceased donors and their 109 recipients who underwent transplantation between 2010 and 2013 at 4 Korean transplantation centers. We investigated the predictive values of donor urinary neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), and L-type fatty acid binding protein (L-FABP) for reduced graft function (RGF). We also developed a prediction model of RGF using these donor biomarkers. RGF was defined as delayed or slow graft function. Multiple logistic regression analysis was used to generate a prediction model, which was internally validated using a bootstrapping method. Multiple linear regression analysis was used to assess the association of biomarkers with 1-year graft function. Notably, donor urinary NGAL levels were associated with donor AKI (P = 0.014), and donor urinary NGAL and L-FABP were predictive for RGF, with area under the receiver-operating characteristic curves (AUROC) of 0.758 and 0.704 for NGAL and L-FABP, respectively. The best-fit model including donor urinary NGAL, L-FABP, and serum creatinine conveyed a better predictive value for RGF than donor serum creatinine alone (P = 0.02). In addition, we generated a scoring method to predict RGF based on donor urinary NGAL, L-FABP, and serum creatinine levels. Diagnostic performance of the RGF prediction score (AUROC 0.808) was significantly better than that of the DGF calculator (AUROC 0.627) and the kidney donor profile index (AUROC 0.606). Donor urinary L-FABP levels were also predictive of 1-year graft function (P = 0.005). Collectively, these findings suggest donor urinary NGAL and L-FABP to be useful biomarkers for RGF, and support the use of a new scoring system based on donor biomarkers to facilitate decision-making in acceptance and allocation of deceased donor kidneys and contribute to maximal organ utilization.

Transition From Hand-Assisted to Pure Laparoscopic Donor Nephrectomy

Background and Objectives:

We compared perioperative donor outcomes and early graft function of hand-assisted laparoscopic donor nephrectomy (HALDN) and pure laparoscopic donor nephrectomy (PLDN) performed by a single surgeon, to define the feasibility of technical transition from HALDN to PLDN.

Methods:

From October 1, 2012, through June 30, 2014, 60 donor nephrectomies were performed by a single surgeon who lacked experience with laparoscopic renal surgery: the first 30 by HALDN and the last 30 by PLDN. Operative and convalescence parameters were compared, as were intra- and postoperative complications within 90 days according to the Satava and Clavien-Dindo classifications, respectively. Binary logistic regression analysis was used to estimate the association of baseline characteristics with complications.

Results:

Baseline characteristics were similar in the 2 groups, except for American Society of Anesthesiologists score II (10.0% vs 43.3%; P = .007). All procedures were completed as planned. All operative and convalescence parameters of donors and graft outcomes were similar in the 2 groups, as were overall rates of intraoperative (43.3% vs 36.7%, P = .598) and postoperative (86.7% vs 70.0%; P = .209) complications. No factor was significantly predictive of intraoperative complications, whereas sex (female vs male, odds ratio, 0.183; P = .029) and learning curve (odds ratio, 0.602; P = .036) were significant determinants of postoperative complication.

Conclusion:

The technical transition from HALDN to PLDN does not involve a steep learning curve for surgeons less experienced with laparoscopic renal surgery and maintains similar perioperative donor and graft outcomes.

Influence of the Interval Between Renal Computed Tomographic Angiography and Kidney Transplantation on Allograft Function: A Prospective, Randomized, Controlled Trial

BACKGROUND

Computed tomographic angiography (CTA) requires contrast agents that may cause nephropathy. We wanted to assess whether donors using contrast agents long or immediately before nephrectomy affects recipient allograft function.

METHODS

Pairs of kidney donors and recipients in our center were recruited between May 2012 and October 2014. They were randomly allocated into the preemptive CTA (pCTA) group, in which the donors underwent CTA at least 60 days before nephrectomy, or the delayed CTA (dCTA) group, in which donors underwent CTA within 3 days before nephrectomy.

RESULTS

Both groups included 43 recipients. Recovery time to normal serum creatinine levels and the numbers of recipients who had slow graft function or normal cystatin C at 1 month were significantly different between groups. At 6-month follow-up, both groups showed similar serum creatinine levels, estimated glomerular filtration rate, and rates of acute rejection. No participant had graft failure. The pCTA group had a significantly lower number of recipients with proteinuria (5 versus 13, P = .034) and slighter proteinuria (spot urine protein/Cr, 0.09 ± 0.05 versus 0.14 ± 0.07, P = .047).

CONCLUSIONS

Performing renal CTA on donors immediately before nephrectomy may increase the risk of proteinuria in recipients, but it does not appear to affect allograft function recovery or survival rate (Chinese Clinical Trial Registration: ChiCTR-TRC-11002108).

Defining delayed graft function after renal transplantation: simplest is best

BACKGROUND

Delayed graft function (DGF) after renal transplantation can be diagnosed according to several different definitions, complicating comparison between studies that use DGF as an endpoint. This is a particular problem after transplantation with kidneys from donation after circulatory death (DCD) kidneys, because DGF is common, and its relationship to early graft failure may differ depending on the definition of DGF.

METHODS

The presence of DGF in 213 donation after brain death (DBD) and 312 DCD kidney transplants from October 2005 to August 2011 was determined according to 10 different, but widely used, definitions (based on dialysis requirements, creatinine changes, or both). The relationship of DGF to graft function and graft survival was determined.

RESULTS

The incidence of DGF varied widely depending on the definition used (DBD; 24%-70%: DCD; 41%-91%). For kidneys from DCD donors, development of DGF was only associated with poorer 1-year estimated glomerular filtration rate for 1 of 10 definitions of DGF, and no definition of DGF was associated with impaired graft survival. Conversely, for DBD kidneys, DGF, as defined in 9 of 10 different ways, was associated with poorer 1-year estimated glomerular filtration rate and inferior graft survival. Importantly, the predictive power for poorer transplant outcome was comparable for all definitions of DGF.

CONCLUSION

No definition of DGF is superior. We suggest that the most widely used and most easily calculated definition--the use of dialysis in the first postoperative week--should be universally adopted as the definition of DGF clinically and as a study endpoint.

Slow early graft function: a neglected entity after renal transplantation

BACKGROUND

After renal transplantation, early graft function (EGF) can be divided into delayed graft function (DGF), slow graft function (SGF) and immediate graft function (IGF). DGF is well documented. However, when evaluating the long-term significance of early function, the literature shows conflicting definitions and inconsistent results. In addition, SGF, a new entity separate to DGF and IGF, is a recent and poorly understood development.

AIM

To investigate the risk factors for and the impact of poor EGF (PEGF) on long-term outcome.

METHODS

This retrospective study reviewed the records of local adult patients who underwent renal transplantation at the Groote Schuur Hospital (Cape Town, South Africa) between 2004 and 2008. EGF was divided according to day 5 serum creatinine into IGF (serum creatinine <150 µmol/l), SGF (serum creatinine >150 but <450 µmol/l) and DGF (serum creatinine >450 µmol/l or dialysis in the first week). DGF and SGF together comprised PEGF, with IGF alone representing good EGF (GEGF).

RESULTS

A total of 121 patients (77 men, 44 women; mean age 39 years, range 14-67) were included in the study. Eighteen were excluded due to nephrectomy (n = 8), death (n = 6) or loss to follow-up (n = 4) within the first year. Analysis of cadaveric donors showed no significant risk factors for PEGF with the exception of cold ischaemic time, which differed significantly between the GEGF and PEGF groups, with means of 12 and 16 h, respectively (p = 0.013). Considering both living and cadaveric grafts, the 1-year estimated glomerular filtration rate (eGFR) was significantly different between IGF and DGF (p = 0.038) as well as between IGF and SGF (p = 0.028), with no significant difference between SGF and DGF (p > 0.05). A comparison of the PEGF and GEGF groups yielded significantly different 1-year eGFR values (60 and 50 ml/min, respectively; p = 0.07), with PEGF also associated with a longer hospital stay (20 vs. 14 days; p = 0.00005). Acute rejection was independently associated with a lower 1-year eGFR (p = 0.028), but in the absence of rejection, GEGF and PEGF remained significantly different with regards to 1-year eGFR (p = 0.024).

CONCLUSIONS

SGF is not related to IGF but rather to DGF and should thus be regarded as a form of PEGF as opposed to GEGF. PEGF has a worse long-term outcome, and this indicates the need for increased efforts in its prevention and greater attention to its management.