Risk and prediction of kidney failure early after liver transplantation

BACKGROUND

Kidney disease is common after liver transplantation (LT), but postoperative kidney failure is difficult to predict. Current guidelines recommend simultaneous liver-kidney transplantation (SLKT) in patients with pre-LT estimated glomerular filtration rate (eGFR) below 30-40 mL/min, which might be too liberal. The aim of this study was to evaluate the risk of kidney failure after LT. We also assessed the predictive ability of pretransplantation eGFR using various equations.

METHODS

This single-center study included patients undergoing primary LT 2006-2020. Patients undergoing simultaneous liver-kidney transplantations or on dialysis before LT were analysed separately. We calculated 5 different eGFR equations measured just before LT and assessed their predictive ability using Kaplan-Meier cumulative incidence estimates.

RESULTS

Among 556 LT patients with a median follow-up of 5.0 years (IQR 2.0-8.5), 20 developed kidney failure during follow-up, 7 of them within 1-year post LT. Six of these 7 suffered from major perioperative complications. Depending on the eGFR equation used, the incidence of kidney failure within 1-year was 3.9-6.7% at pre-LT eGFR-values <30 mL/min, 1.2-3.1% at eGFR 30-60 mL/min, and 0.6-0.9% at eGFR >60 mL/min.

CONCLUSIONS

Kidney failure within 1-year post-LT could not be reliably predicted by pre-LT eGFR. However, kidney failure was uncommon even in patients with severely reduced pre-LT glomerular filtration rate (eGFR <30 mL/min), and extremely rare in patients unaffected by major perioperative complications. Our data prompts further consideration regarding the guidelines for SLKT in patients with a reduced preoperative eGFR.

Assessment of glomerular filtration rate in patients with cirrhosis: Available tools and perspectives

Renal dysfunction often complicates the course of liver disease, resulting in higher morbidity and mortality. The accurate assessment of kidney function in these patients is essential to early identify, stage and treat renal impairment as well as to better predict the prognosis, prioritize the patients for liver transplantation and decide whether to opt for simultaneous liver-kidney transplants. This review analyses the available tools for direct or indirect assessment of glomerular filtration rate, focusing on the flaws and strengths of each method in the specific setting of cirrhosis. The aim is to deliver a clear-cut view on this complex issue, trying to point out which strategies to prefer in this context, especially in the peculiar setting of liver transplantation. Moreover, a glance is given at future promising tools for glomerular filtration rate assessment, including new biomarkers and new equations specifically modelled for the cirrhotic population.

Trends and Outcomes of Hypothermic Machine Perfusion Preservation of Kidney Allografts in Simultaneous Liver and Kidney Transplantation in the United States

Optimal kidney graft outcomes after simultaneous liver-kidney (SLK) transplant may be threatened by the increased cold ischemia time and hemodynamic perturbations of dual organ transplantation. Hypothermic machine perfusion (MP) of kidney allografts may mitigate these effects. We analyzed U.S. trends and renal outcomes of hypothermic non-oxygenated MP vs. static cold storage (CS) of kidney grafts from 6,689 SLK transplants performed between 2005 and 2020 using the United Network for Organ Sharing database. Outcomes included delayed graft function (DGF), primary non-function (PNF), and kidney graft survival (GS). Overall, 17.2% of kidney allografts were placed on MP. Kidney cold ischemia time was longer in the MP group (median 12.8 vs. 10.0 h; p < 0.001). Nationally, MP utilization in SLK increased from <3% in 2005 to >25% by 2019. Center preference was the primary determinant of whether a graft underwent MP vs. CS (intraclass correlation coefficient 65.0%). MP reduced DGF (adjusted OR 0.74; p = 0.008), but not PNF (p = 0.637). Improved GS with MP was only observed with Kidney Donor Profile Index <20% (HR 0.71; p = 0.030). Kidney MP has increased significantly in SLK in the U.S. in a heterogeneous manner and with variable short-term benefits. Additional studies are needed to determine the ideal utilization for MP in SLK.

The impact of multi-organ transplant allocation priority on waitlisted kidney transplant candidates

Kidney-alone transplant (KAT) candidates may be disadvantaged by the allocation priority given to multi-organ transplant (MOT) candidates. This study identified potential KAT candidates not receiving a given kidney offer due to its allocation for MOT. Using the Organ Procurement and Transplant Network (OPTN) database, we identified deceased donors from 2002 to 2017 who had one kidney allocated for MOT and the other kidney allocated for KAT or simultaneous pancreas-kidney transplant (SPK) (n = 7,378). Potential transplant recipient data were used to identify the "next-sequential KAT candidate" who would have received a given kidney offer had it not been allocated to a higher prioritized MOT candidate. In this analysis, next-sequential KAT candidates were younger (p < .001), more likely to be racial/ethnic minorities (p < .001), and more highly sensitized than MOT recipients (p < .001). A total of 2,113 (28.6%) next-sequential KAT candidates subsequently either died or were removed from the waiting list without receiving a transplant. In a multivariable model, despite adjacent position on the kidney match-run, mortality risk was significantly higher for next-sequential KAT candidates compared to KAT/SPK recipients (hazard ratio 1.55, 95% confidence interval 1.44, 1.66). These results highlight implications of MOT allocation prioritization, and potential consequences to KAT candidates prioritized below MOT candidates.

Early Kidney Allograft Failure After Simultaneous Liver-kidney Transplantation: Evidence for Utilization of the Safety Net?

BACKGROUND

With the implementation of the "Safety Net," we aimed to determine the impact of simultaneous liver-kidney transplantation (SLKT), as compared to kidney transplant after liver transplant (KALT), on kidney allograft failure (KF).

METHODS

An analysis of the UNOS database for all adult patients who received either an SLKT or KALT from 2002 to 2017. The outcomes were 90-day KF and 1-year KF (as reported to UNOS, at 90- and 365-day postkidney transplant, respectively). We compared the following groups of patients: SLKT <25 (SLKT with final model for end-stage liver disease [MELD] <25), SLKT25/35 (MELD ≥25/<35), and SLKT35 (MELD ≥35) to KALT.

RESULTS

Of the 6276 patients, there were 1481 KALT, 1579 SLKT <25, 1832 SLKT25/35, and 1384 SLKT ≥35. The proportion of patients with 90-day and 1-year KF increased significantly among the KALT, SLKT <25, SLKT25/35, and SLKT ≥35 groups (P < 0.001; test for trend): 90-day KF: 3.3% versus 5.5% versus 7.3% versus 9.3% and 1-year KF: 5.1% versus 9.4% versus 12.3% versus 14.7%. After adjustment and compared with KALT, beginning at an MELD ≥25 those undergoing SLKT had significantly higher risk of 90-day and 1-year KF: 90-day KF: SLKT25/35: hazard ratio, 1.6(1.0-2.3); SLKT ≥35: 2.1(1.3-3.3); 1-year KF: SLKT25/35: hazard ratio, 1.7(1.2-2.4); SLKT ≥35: 2.1(1.5-3.0).

CONCLUSIONS

As compared to KALT recipients, SLKT recipients with an MELD ≥25 had significantly higher risk of early KF. Given the now well-established "Safety Net," KALT may serve as an opportunity to improve kidney outcomes in patients with an MELD ≥25.

Deceased vs living donor grafts for pediatric simultaneous liver-kidney transplantation: A single-center experience

Introduction

In conditions of limited experience of pediatric simultaneous liver‐kidney transplantation (SLKT) using grafts from living and deceased donors, there is a certain need to validate the approach.

Patients

The retrospective study of 18 pediatric patients who received SLKT between 2008 and 2019.

Results

Grafts were obtained from both living and deceased donors. The patients’ age ranged from 2 to 16 years (9 years ±4). The body weight of the children varied from 9.5 to 39 kg (22 kg ±9). The follow‐up period lasted from 1 to 109 months (median 38 months ±35). The various graft combinations were used in both groups. There was no mortality during the follow‐up. There was no significant difference in baseline parameters in recipients who received grafts from living and deceased donors except age (7.5 years ±2.2 vs 11.8 years ±4.1; P = .038). Rate of complications > grade II was higher among recipients of deceased donor SLKT (7.7% vs 60%; OR, 7.8; 95% CI, 1.04‐58.48; P = .044). All the patients are alive with both grafts functioning. All the living donors returned to the normal life.

Conclusion

SLKT is a safe and effective procedure for children with both simultaneous end‐stage liver disease and end‐stage renal disease. Both living donor partial liver and kidney transplantation and deceased donor liver‐kidney transplantation can be considered as safe and feasible options.

Peritoneal Dialysis Is Feasible as a Bridge to Combined Liver-Kidney Transplant

Patients with combined liver and kidney failure may remain on dialysis for years while awaiting simultaneous liver-kidney transplantation (SLKT). The role of peritoneal dialysis (PD) in patients with advanced liver and kidney failure awaiting SLKT remains to be defined. We present our single-institution experience with PD in cirrhotics, 3 of whom went on to receive successful SLKT. Patients initiated in our PD program between 2006 and 2016 who had both liver and kidney failure were identified. Medical and dialysis records were reviewed retrospectively. Outcomes included mortality, transplantation status, hospitalizations, need for large-volume paracentesis (LVP), peritonitis rates, PD treatment longevity, and albumin level. Twelve patients with combined liver and kidney failure were treated in our PD program. No patients died and 3 patients received SLKT. Four patients remain listed for transplantation. There was no need for LVP after initiating dialysis. The rate of peritonitis was 0.2 events per patient per year, most commonly due to coagulase-negative Staphylococcus Our data illustrate that PD is a viable bridging therapy for patients with liver and kidney failure who await SLKT.

Donor-specific hypo-responsiveness occurs in simultaneous liver-kidney transplant recipients after the first year

Kidney allografts of patients who undergo simultaneous liver-kidney transplantation incur less immune-mediated injury, and retain better function compared to other kidney allografts. To characterize the host alloimmune responses in 28 of these patients, we measured the donor-specific alloresponsiveness and phenotypes of peripheral blood cells after the first year. These values were then compared to those of 61 similarly immunosuppressed recipients of a solitary kidney or 31 recipients of liver allografts. Four multicolor, non-overlapping flow cytometry protocols were used to assess the immunophenotypes. Mixed cell cultures with donor or third party cells were used to measure cell proliferation and interferon gamma production. Despite a significant overlap, simultaneous liver-kidney transplant recipients had a lower overall frequency of circulating CD8⁺, activated CD4⁺ and effector memory T cells, compared to solitary kidney transplant recipients. Simultaneous liver-kidney transplant recipient T cells had a significantly lower proliferative response to the donor cells compared to solitary kidney recipients (11.9 vs. 42.9%), although their response to third party cells was unaltered. The frequency of interferon gamma producing alloreactive T cells in simultaneous liver-kidney transplant recipients was significantly lower than that of solitary kidney transplant recipients. Flow cytometric analysis of the mixed cultures demonstrated that both alloreactive CD4⁺ and CD8⁺ compartments of the simultaneous liver-kidney transplant recipient circulating blood cells were smaller. Thus, the phenotypic and functional characteristics of the circulating blood cells of the simultaneous liver-kidney transplant recipients resembled those of solitary liver transplant recipients, and appear to be associated with donor-specific hypo-alloresponsiveness.

Unique molecular changes in kidney allografts after simultaneous liver-kidney compared with solitary kidney transplantation

Kidney allografts transplanted simultaneously with liver allografts from the same donor are known to be immunologically privileged. This is especially evident in recipients with high levels of donor-specific anti-HLA antibodies. Here we investigated the mechanisms of liver's protective impact using gene expression in the kidney allograft. Select solitary kidney transplant or simultaneous liver-kidney transplant recipients were retrospectively reviewed and separated into four groups: 16 cross-match negative kidney transplants, 15 cross-match positive kidney transplants, 12 cross-match negative simultaneous liver-kidney transplants, and nine cross-match-positive simultaneous liver-kidney transplants. Surveillance biopsies of cross-match-positive kidney transplants had increased expression of genes associated with donor-specific antigens, inflammation, and endothelial cell activation compared to cross-match-negative kidney transplants. These changes were not found in cross-match-positive simultaneous liver-kidney transplant biopsies when compared to cross-match-negative simultaneous liver-kidney transplants. In addition, simultaneously transplanting a liver markedly increased renal expression of genes associated with tissue integrity/metabolism, regardless of the cross-match status. While the expression of inflammatory gene sets in cross-match-positive simultaneous liver-kidney transplants was not completely reduced to the level of cross-match-negative kidney transplants, the downstream effects of donor-specific anti-HLA antibodies were blocked. Thus, simultaneous liver-kidney transplants can have a profound impact on the kidney allograft, not only by decreasing inflammation and avoiding endothelial cell activation in cross-match-positive recipients, but also by increasing processes associated with tissue integrity/metabolism by unknown mechanisms.

Anaesthesia and intensive care for simultaneous liver-kidney transplantation: A single-centre experience with 12 recipients

Background and Aims:

The perioperative management of patients presenting for simultaneous liver and kidney transplantation (SLKT) is a complex process. We analysed SLKTs performed in our institution to identify preoperative, intraoperative and post-operative challenges encountered in the management.

Methods:

We retrospectively studied the case records of 12 patients who underwent SLKT between 2009 and 2014 and analysed details of pre-operative evaluation and optimisation, intraoperative anaesthetic management and the implications of use of perioperative continuous renal replacement therapy (CRRT) and the post-operative course of these patients.

Results:

Of the total 12 cases, 4 were under 16 years of age. The indications for SLKT were primary hyperoxaluria (5), congenital hepatic fibrosis with polycystic kidney disease (2), ethanol-related end-stage liver disease (ESLD) with hepatorenal syndrome type 1 (1). Four patients had ESLD with end-stage renal disease due to other causes. Six recipients received live donor grafts and 6 patients received cadaveric grafts. Seven patients received intraoperative CRRT. Mean duration of surgery was 12.5 h. Cardiac output monitors used were trans-oesophageal echocardiogram (2), pulmonary artery catheter (1) and pulse contour cardiac output monitor (3). There was 1 sepsis-related mortality on 7^th post-operative day.

Conclusion:

A thorough pre-operative evaluation and optimisation, knowledge and anticipation of potential problems, and meticulous intraoperative fluid management guided by appropriate monitoring and use of CRRT when needed can help in achieving successful outcomes.

Decreased chronic cellular and antibody-mediated injury in the kidney following simultaneous liver-kidney transplantation

In simultaneous liver-kidney transplantation (SLK), the liver can protect the kidney from hyperacute rejection and may also decrease acute cellular rejection rates. Whether the liver protects against chronic injury is unknown. To answer this we studied renal allograft surveillance biopsies in 68 consecutive SLK recipients (14 with donor-specific alloantibodies at transplantation [DSA+], 54 with low or no DSA, [DSA-]). These were compared with biopsies of a matched cohort of kidney transplant alone (KTA) recipients (28 DSA+, 108 DSA-). Overall 5-year patient and graft survival was not different: 93.8% and 91.2% in SLK, and 91.9% and 77.1% in KTA. In DSA+ recipients, KTA had a significantly higher incidence of acute antibody-mediated rejection (46.4% vs. 7.1%) and chronic transplant glomerulopathy (53.6% vs. 0%). In DSA- recipients at 5 years, KTA had a significantly higher cumulative incidence of T cell-mediated rejection (clinical plus subclinical, 30.6% vs. 7.4%). By 5 years, DSA+ KTA had a 44% decline in mean GFR while DSA+SLK had stable GFR. In DSA- KTA, the incidence of a combined endpoint of renal allograft loss or over a 50% decline in GFR was significantly higher (20.4% vs. 7.4%). Simultaneously transplanted liver allograft was the most predictive factor for a significantly lower incidence of cellular (odds ratio 0.13, 95% confidence interval 0.06-0.27) and antibody-mediated injury (odds ratio 0.11, confidence interval 0.03-0.32), as well as graft functional decline (odds ratio 0.22, confidence interval 0.06-0.59). Thus, SLK is associated with reduced chronic cellular and antibody-mediated alloimmune injury in the kidney allograft.

Propensity score-based survival benefit of simultaneous liver-kidney transplant over liver transplant alone for recipients with pretransplant renal dysfunction

The survival benefit of simultaneous liver-kidney transplantation (SLKT) over liver transplantation alone (LTA) is unclear from the current literature. Additionally, the role of donor kidney quality, measured by the kidney donor risk index (KDRI), in survival benefit of SLKT is not studied. We compared survival benefit after SLKT and LTA among recipients with similar pretransplant renal dysfunction using novel methodology, specifically with respect to survival probability and area under the survival curve by dialysis status and KDRI. Data were obtained from the Scientific Registry of Transplant Recipients. The study cohort included patients with pre-liver transplantation (LT) renal dysfunction who were wait-listed and received either a SLKT (n = 1326) or a LTA (n = 4283) between March 1, 2002 and December 31, 2009. Inverse Probability of Treatment Weighting-SLKT and LTA survival curves, along with the 5-year area under the survival curve, were computed by dialysis status at transplant. The difference in the area under the curve represents the average additional survival time gained via SLKT over LTA. For patients not on dialysis, SLKT resulted in a significant 3.7-month gain in 5-year mean posttransplant survival time. The decrease in mortality rate differs significantly by KDRI, and an estimated 76% of SLKT recipients received a kidney with KDRI sufficiently low for mortality. The mortality decrease for SLKT was concentrated in the first year after transplant. The difference between SLKT and LTA 5-year mean posttransplant survival time was 1.4 months and was nonsignificant for patients on dialysis. In conclusion, the propensity score-adjusted survival among SLKT and LTA recipients was similar for those who were on dialysis at LT. Although statistically significant, the survival advantage of SLKT over LTA was of marginal clinical significance among patients not on dialysis and occurred only if the donor kidney was of sufficient quality. These results should be considered in the ongoing debate regarding the allocation of kidneys to extra-renal transplant candidates.

Pathogenesis of Hepatorenal Syndrome: Implications for Therapy

Patients with cirrhosis are prone to develop acute kidney injury (AKI) due to a number of causes, including bacterial infections with or without septic shock, hypovolemia, administration of nephrotoxic drugs, and intrinsic kidney diseases, among others. Most importantly, patients with advanced cirrhosis develop a distinctive cause of AKI, characterized by rapidly progressive glomerular filtration rate loss associated with marked disturbances in circulatory function in the absence of obvious pathologic abnormalities in the kidneys, known as hepatorenal syndrome (HRS). Decreased kidney function results from intense renal vasoconstriction secondary to the complex circulatory changes of cirrhosis with splanchnic vasodilatation and effective hypovolemia. Beyond activation of vasoactive systems, factors including impaired renal blood flow autoregulation and systemic inflammation may play a role in the development of HRS. Most patients improve with albumin and vasopressors; however, the prognosis of HRS remains very poor. Novel biomarkers may be helpful in distinguishing HRS from other causes of AKI in patients with cirrhosis.

Comparative effectiveness of liver transplant strategies for end-stage liver disease patients on renal replacement therapy

There are complex risk-benefit tradeoffs with different transplantation strategies for end-stage liver disease patients on renal support. Using a Markov discrete-time state transition model, we compared survival for this group with 3 strategies: simultaneous liver-kidney (SLK) transplantation, liver transplantation alone (LTA) followed by immediate kidney transplantation if renal function did not recover, and LTA followed by placement on the kidney transplant wait list. Patients were followed for 30 years from the age of 50 years. The probabilities of events were synthesized from population data and clinical trials according to Model for End-Stage Liver Disease (MELD) scores (21-30 and >30) to estimate input parameters. Sensitivity analyses tested the impact of uncertainty on survival. Overall, the highest survival rates were seen with SLK transplantation for both MELD score groups (82.8% for MELD scores of 21-30 and 82.5% for MELD scores > 30 at 1 year), albeit at the cost of using kidneys that might not be needed. Liver transplantation followed by kidney transplantation led to higher survival rates (77.3% and 76.4%, respectively, at 1 year) than placement on the kidney transplant wait list (75.1% and 74.3%, respectively, at 1 year). When uncertainty was considered, the results indicated that the waiting time and renal recovery affected conclusions about survival after SLK transplantation and liver transplantation, respectively. The subgroups with the longest durations of pretransplant renal replacement therapy and highest MELD scores had the largest absolute increases in survival with SLK transplantation versus sequential transplantation. In conclusion, the findings demonstrate the inherent tension in choices about the use of available kidneys and suggest that performing liver transplantation and using renal transplantation only for those who fail to recover their native renal function could free up available donor kidneys. These results could inform discussions about transplantation policy.