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

Association between peri-transplant acid-base parameters and graft dysfunction types in kidney transplantation

Perioperative acid-base disturbance could be informative regarding the possible slow graft function (SGF) or delayed graft function (DGF) development. There is a lack of data regarding the relationship between perioperative acid-base parameters and graft dysfunction in kidney transplant (KT) recipients. We aim to determine the incidence of graft dysfunction types and the association between them and acid-base parameters. We performed a prospective, cohort study on 54 adults, KT recipients, between 1st of January 2019 and 31st of December 2019. Graft function was defined and classified in three categories: immediate graft function (IGF) (serum creatinine < 3 mg/dL at day 5 after KT), SGF (serum creatinine ≥ 3mg/dL at day 5 or ≥ 2.5mg dL at day 7 after KT) and DGF (the need for at least one dialysis treatment in the first week after kidney transplantation). Among the 54 KT recipients, the incidence of SGF and DGF was 13% and 11.1%, respectively. SGF was significantly associated with lower intraoperative pH (7.26± 0.05 vs 7.35± 0.06, p= 0.004), preoperative and intraoperative base excess (BE) [-7.0 (-10.0 ߝ -6.0) vs -3.4 (-7.8 ߝ - 2.1) mmol/L, p= 0.04 and -10.3 (-11.0 ߝ -9.1) vs -4.0 (-6.3 ߝ - 3.0) mmol/L, p= 0.002, respectively] and serum bicarbonate (HCO3-) (16.0± 2.7 vs 19.3± 3.4 mmol/L, p= 0.01 and 14.1± 1.9 vs 18.8± 3.2 mmol/L, p= 0.002 respectively), compared to IGF. DGF was significantly associated with lower intraoperative values of pH (7.27± 0.05 vs 7.35± 0.06, p= 0.003), BE [-7.1 (-10.9 ߝ -6.1) vs -4.0 (-6.3 ߝ - 3.0) mmol/L, p= 0.02] and HCO3- (15.9± 2.4 vs 18.8± 3.2 mmol/L, p=0.02) compared to IGF. No differences were observed between SGF and DGF patients in any of the perioperative acid-base parameters. In conclusion we found that kidney graft dysfunction types are associated with perioperative acid-base parameters and perioperative metabolic acidosis could provide important information to predict SGF or DGF occurrence.

Development and validation of a novel nomogram model for predicting delayed graft function in deceased donor kidney transplantation based on pre-transplant biopsies

BACKGROUND

Delayed graft function (DGF) is an important complication after kidney transplantation surgery. The present study aimed to develop and validate a nomogram for preoperative prediction of DGF on the basis of clinical and histological risk factors.

METHODS

The prediction model was constructed in a development cohort comprising 492 kidney transplant recipients from May 2018 to December 2019. Data regarding donor and recipient characteristics, pre-transplantation biopsy results, and machine perfusion parameters were collected, and univariate analysis was performed. The least absolute shrinkage and selection operator regression model was used for variable selection. The prediction model was developed by multivariate logistic regression analysis and presented as a nomogram. An external validation cohort comprising 105 transplantation cases from January 2020 to April 2020 was included in the analysis.

RESULTS

266 donors were included in the development cohort, 458 kidneys (93.1%) were preserved by hypothermic machine perfusion (HMP), 96 (19.51%) of 492 recipients developed DGF. Twenty-eight variables measured before transplantation surgery were included in the LASSO regression model. The nomogram consisted of 12 variables from donor characteristics, pre-transplantation biopsy results and machine perfusion parameters. Internal and external validation showed good discrimination and calibration of the nomogram, with Area Under Curve (AUC) 0.83 (95%CI, 0.78-0.88) and 0.87 (95%CI, 0.80-0.94). Decision curve analysis demonstrated that the nomogram was clinically useful.

CONCLUSION

A DGF predicting nomogram was developed that incorporated donor characteristics, pre-transplantation biopsy results, and machine perfusion parameters. This nomogram can be conveniently used for preoperative individualized prediction of DGF in kidney transplant recipients.

Urinary Biomarkers for Cell Cycle Arrest TIMP-2 and IGFBP7 for Prediction of Graft Function Recovery after Kidney Transplantation

TIMP-2 and IGFBP7 have been identified and validated for the early detection of renal injury in critically ill patients, but data on recovery of allograft function after kidney transplantation (KTx) are scarce. In a prospective observational multicenter cohort study of renal transplant recipients, urinary [TIMP-2] × [IGFBP7] was evaluated daily from day 1 to 7 after KTx. Different stages of early graft function were defined: immediate graft function (IGF) (decrease ≥ 10% in serum creatinine (s-crea) within 24 h post KTx); slow graft function (SGF) (decrease in s-crea < 10% within 24 h post KTx); and delayed graft function (DGF) (any dialysis needed within the first week after KTx). A total of 186 patients were analyzed. [TIMP-2] × [IGFBP7] was significantly elevated as early as day 1 in patients with DGF compared to SGF and IGF. ROC analysis of [TIMP-2] × [IGFBP7] at day 1 post-transplant for event "Non-DGF" revealed a cut-off value of 0.9 (ng/mL)2/1000 with a sensitivity of 87% and a specificity of 71%. The positive predictive value for non-DGF was 93%. [TIMP-2] × [IGFBP7] measured at day 1 after KTx can predict early recovery of transplant function and is therefore a valuable biomarker for clinical decision making.

Laparo-Endoscopic Single-Site Left Donor Nephrectomy In Patients With Uncommon Renal Vascular Anatomy: Does the Technique Make a Difference?

BACKGROUND

To compare donor and recipient outcomes in patients with renal artery and ante-aortic renal vein vs unusual renal vascular anatomy undergoing laparoendoscopic single-site donor nephrectomy (LESSDN).

METHODS

A retrospective chart review of the comparative study of donor and recipient outcomes of LESSDN in donors with venous abnormality (n = 28, group A), arterial abnormality (n = 74, group B), and standard donors (n = 248, group C).

RESULTS

From September 2016 to August 2022, 350 left LESSDN were performed. The most common anomalies in group A were the retro-aortic and 2 renal veins in 12 patients each. In group B, 72 and 2 patients had 2 and 3 renal arteries, respectively. Operative and warm ischemia times were significantly longer in donors with vascular anomalies. Moreover, patient creatinine on discharge was significantly higher in arterial anomalies; it was 1.61 ± 0.22 compared with 1.26 ± 0.43 and 1.25 ± 0.32 mg/dL for patients with no anomalies and venous anomalies, respectively (P < .001). However, serum creatinine levels recovered after 1 month and were comparable between the study groups. Recipients, operative time, and vascular anastomosis time were significantly longer in recipients with vascular anomaly. Slow graft function was higher in group B (6.9%) than in the other groups. One-year graft survival rates were 96.4%, 94.6%, and 97.1% (P = .496).

CONCLUSION

With increased experience, LESSDN in multiple renal arteries and uncommon venous anatomy cases is feasible and safe. Moreover, it does not influence donor or recipient outcomes.

Role of Renal Venous Oxygen Pressure for Renal Function Monitoring After Related Living-Donor Kidney Transplantation: Cohort Study

BACKGROUND

Monitoring of renal function after kidney transplantation (KT) is performed by measuring serum creatinine (SCr), urine volumes (UV), and glomerular filtration rate (GFR). Other methods based on oxygen metabolism, such as the renal venous oxygen pressure (PrvO2), may be useful. The aim of this study was to explore the correlation between PrvO2 and SCr, UV, and GFR 5 days after KT (SCr5, UV5, and GFR5, respectively).

METHODS

We conducted a prospective cohort study in adults scheduled for living donor KT. A venous blood sample was taken from the renal vein after declamping the renal artery, and blood gas determinations were made. Correlation analyses between PrvO2 and SCr5, UV5, and GFR5 were done by calculating Spearman's correlation coefficient with generalized linear models (GLM). A Spearman's correlation analysis was performed between the percentage decrease in SCr (%ΔSCr) and PrvO2. A GLM was also performed to determine the association of PrvO2 with slow graft function (SGF).

RESULTS

The study included 42 patients, of whom 67% were men. The median age was 31 years (IQR, 27-43.5). PrvO2 was negatively correlated with SCr5 (ρ = -0.53, P = .003), and positively correlated with GFR5 (ρ = 0.49, P = .001) and %ΔSCr (ρ = 0.47, P = .002). A higher PrvO2 was associated with an increase in GFR in univariable (β = 1.24, 95% CI, 0.56-1.93, P = .001) and multivariable (β = 1.24, 95% CI, 0.53-1.94, P = .001) analyses. No association was found between PrvO2 and SGF.

CONCLUSION

PrvO2 could be used to monitor renal function in the first 5 days after related living-donor KT, given its good correlation with SCr and GFR.

Optimal Renal Artery-Aorta Angulation Revealed by Flow Simulation

INTRODUCTION

In the circulatory system, the vessel branching angle may have hemodynamic consequences. We hypothesized that there is a hemodynamically optimal range for the renal artery's branching angle.

METHODS

Data on the posttransplant kinetics of estimated glomerular filtration rate (eGFR) were analyzed according to the donor and implant sides (right-to-right and left-to-right position; n = 46). The renal artery branching angle from the aorta of a randomly selected population was measured using an X-ray angiogram (n = 44). Computational fluid dynamics simulation was used to elucidate the hemodynamic effects of angulation.

RESULTS AND DISCUSSION

Renal transplant patients receiving a right donor kidney to the right side showed faster adaptation and higher eGFR values than those receiving a left donor kidney to the right side (eGFR: 65 ± 7 vs. 56 ± 6 mL/min/1.73 m2; p < 0.01). The average branching angle on the left side was 78° and that on the right side was 66°. Simulation results showed that the pressure, volume flow, and velocity were relatively constant between 58° and 88°, indicating that this range is optimal for the kidneys. The turbulent kinetic energy does not change significantly between 58° and 78°.

CONCLUSION

The results suggest that there is an optimal range for the renal artery's branching angle from the aorta where hemodynamic vulnerability caused by the degree of angulation is the lowest, which should be considered during kidney transplantations.

Clinical Outcomes of Transplanted Kidneys from Deceased Donors Using Different Generic Preservation Solutions

Background and Objectives: StoreProtect Plus® is a preserving solution for cold organ storage, with a composition identical to Institute Georges Lopez (IGL-1) solution. The aim of this single center study was to compare the clinical performance of StoreProtect Plus with the generic counterpart of University of Wisconsin preservation fluid, named SPS-1®. Materials and Methods: The clinical outcomes of 168 consecutive organs preserved with StoreProtect Plus solution and 167 organs preserved with SPS-1 solution were compared. During an 18-month post-transplant follow-up period, kidney graft function, the frequency of acute rejection, post-transplant diabetes, and infectious complications, as well as patient and graft survival were analyzed. Results: There was significantly more immediate graft function (IGF) (39.3 vs. 24.0%; p < 0.01) and less slow graft function (SGF) (38.7 vs. 51.5%; p < 0.05) in the StoreProtect Plus group in comparison with the SPS-1 group, whereas the occurrence of DGF was similar in both groups. Long-term kidney graft function was comparable. Multivariate regression analysis showed that the use of StoreProtect Plus vs. SPS-1 solution (rpartial = 0.217; p < 0.001) and the amount of residual diuresis (rpartial = 0.147; p < 0.001) independently increased the occurrence of IGF, whereas Scr > 1.5 mg/dL prior to organ procurement (rpartial = −0.198; p < 0.001), longer CIT (rpartial = −0.170; p < 0.01), and CVD donor death (rpartial = −0.214; p < 0.001) were associated with SGF. Conclusions: The higher occurrence of IGF was found in kidney transplant recipients whose organs were preserved using StoreProtect Plus solution as compared with SPS-1 solution. The two groups did not differ in kidney graft function, the frequency of post-transplant complications, as well as patient and graft survival.

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.

Incidence, risk factors, and long-term outcomes associated with antibody-mediated rejection - The long-term Deterioration of Kidney Allograft Function (DeKAF) prospective cohort study

Major gaps remain in our understanding of antibody-mediated rejection (AMR) after kidney transplant. We examined the incidence, risk factors, response to treatment, and effects on outcomes of AMR at seven transplant programs in the long-term Deterioration of Kidney Allograft Function prospective study cohort. Among 3131 kidney recipients, there were 194 observed AMR cases (6.2%) during (mean ± SD) 4.85 ± 1.86 years of follow-up. Time to AMR was 0.97 ± 1.17 (median, 0.48) years. Risk factors for AMR included younger recipient age, human leukocyte antigen DR mismatches, panel-reactive antibody >0%, positive T- or B-cell cross-match, and delayed graft function. Compared with no AMR, the adjusted time-dependent hazard ratio for death-censored graft failure is 10.1 (95% confidence interval, 6.5-15.7) for all AMR patients, 4.0 (2.5, 9.1) for early AMR (<90 days after transplant), and 24.0 (14.0-41.1) for late AMR (≥90 days after transplant). Patients were treated with different therapeutic combinations. Of 194 kidney transplant recipients with AMR, 50 (25.8%) did not respond to treatment, defined as second AMR within 100 days or no improvement in estimated glomerular filtration rate by 42 days. Long-term outcomes after AMR are poor, regardless of the initial response to treatment. Better prevention and new therapeutic strategies are needed to improve long-term allograft survival.

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.

Relevance of KDPI value and acute rejection on kidney transplant outcomes in recipients with delayed graft function - a retrospective study

Delayed graft function (DGF) is associated with poorer graft survival and higher rate of acute rejection (AR). It is unknown whether this negative influence relies on the increased risk of AR or the DGF itself. The different Kidney Donor Profile Index (KDPI) values may also play a role in this interaction. Retrospective study aimed to evaluate the impact of DGF on graft function and graft survival in a subset of KT recipients (2004-2017). We also analyzed the relationship between KDPI and DGF. The study includes 601 KT, 226 of them (37%) developed DGF. Graft survival was lower in patients with DGF compared with non-DGF patients. Multivariable analysis revealed DGF as risk factor for graft loss, independently of the presence or not of acute rejection. Between DGF patients, we observed poorer graft survival in patients with higher KDPI value (>85%). We observed a trend of a greater impact of KDPI in patients with DGF, although this interaction was not statistically significant. Additionally, we observed poorer 12-month graft function in DGF patients. DGF is related to poorer graft survival independently of the developed acute rejection. This negative impact might be influenced by high KDPI values.

Early graft function and intrarenal resistant index after kidney transplantation using Biolasol-A new solid organ preservation fluid

Biolasol is a newly developed preserving solution for cold organ storage prior to transplantation. To date, only animal model experiments results are available. The aim of this single-center analysis was to summarize the clinical experience concerning the early post-transplant course of kidney grafts preserved with Biolasol in comparison with other preservation solutions. Before transplantation, 173 kidney grafts were preserved using Biolasol and 240 organs with other solutions (University of Wisconsin-UW, Institute Georges Lopez-IGL-1, or StoreProtect Plus solutions). Early graft function was defined based on serum creatinine concentration at day 3 (<3 mg/dL-immediate graft function, IGF or >3 mg/dL-slow graft function, SGF) or the need of dialysis therapy during first post-operative week (delayed graft function, DGF). The analysis included intrarenal resistive indices measured by Doppler sonography early after transplantation and before discharge from the hospital. IGF was more frequent in patients with organs preserved with IGL-1 (33.5%) and StoreProtect Plus (38.8%) than Biolasol (18.5%), whereas there was no difference in the occurrence of DGF. Both initial and discharge median resistance index values were significantly higher in the Biolasol subgroup (0.77 and 0.75) than in all three other subgroups (P values for all comparisons <.001), also after 1:1 propensity score matching for baseline characteristics. Multiple logistic regression analysis based on the propensity score-matched cohort revealed that the use of Biolasol solution [OR 0.59 (0.35-0.98); P < .05] independently decreased the occurrence of IGF. In our single-center clinical experience, kidney preservation using Biolasol solution was associated with significantly higher intrarenal resistant index in comparison with other preservation fluids, as well as worse early graft function than in the IGL-1 and the StoreProtect Plus subgroups. Long-term follow-up is needed in order to assess the kidney graft and patient survival.