Creatinine- versus cystatine C-based equations in assessing the renal function of candidates for liver transplantation with cirrhosis

Novel indications for referral and care for simultaneous liver kidney transplant recipients

PURPOSE OF REVIEW

Kidney dysfunction is challenging in liver transplant candidates to determine whether it is reversible or not. This review focuses on the pertinent data on how to best approach liver transplant candidates with kidney dysfunction in the current era after implementing the simultaneous liver kidney (SLK) allocation policy and safety net.

RECENT FINDINGS

The implementation of the SLK policy inverted the steady rise in SLK transplants and improved the utilization of high-quality kidneys. Access to kidney transplantation following liver transplant alone (LTA) increased with favorable outcomes. Estimating GFR in liver transplant candidates remains challenging, and innovative methods are needed. SLK provided superior patient and graft survival compared to LTA only for patients with advanced CKD and dialysis at least 3 months. SLK can provide immunological protection against kidney rejection in highly sensitized candidates. Post-SLK transplant care is complex, with an increased risk of complications and hospitalization.

SUMMARY

The SLK policy improved kidney access and utilization. Transplant centers are encouraged, under the safety net, to reserve SLK for liver transplant candidates with advanced CKD or dialysis at least 3 months while allowing lower thresholds for highly sensitized patients. Herein, we propose a practical approach to liver transplant candidates with kidney dysfunction.

Multiparametric renal function assessment in cirrhotic patients shows high prevalence of medically actionable changes in multiple modules

AIM

Renal dysfunction is a common complication of cirrhosis, occurring either as part of multiorgan involvement in acute illness or secondary to advanced liver disease. To date, no study has comprehensively assessed multiple renal function parameters in hospitalized patients with cirrhosis through a multiparametric analysis of renal biochemistry markers.

METHODS

We conducted a retrospective, observational study including all consecutive patients hospitalized with cirrhosis who underwent a 43-multiparametric renal function assessment between January 1, 2021, and June 30, 2023.

RESULTS

All patients showed at least one of the following renal abnormalities: Kidney Disease: Improving Global Outcomes stage G2 or higher, sodium and/or chloride excretion fraction <1%, electrolyte-free water clearance <0.4 mL/min, or tubular maximum phosphate reabsorption capacity <0.8 mmol/L. The estimated glomerular filtration rate equations significantly overestimated the measured creatinine clearance with median differences of +14 mL/min/1.73 m2 (95% CI 6-29) and +9 mL/min/1.73 m2 (95% CI 2-15) for European Kidney Function Consortium equations, respectively. Notably, 54% and 39% of patients demonstrated estimated glomerular filtration rates exceeding 30% of the measured creatinine clearance when the Chronic Kidney Disease - Epidemiology Collaboration and European Kidney Function Consortium formulas were employed, respectively. Substantial discrepancies in Kidney Disease: Improving Global Outcomes stage assignments were observed between the estimated glomerular filtration rate- and measured creatinine clearance-based assessments.

CONCLUSIONS

This study underscores the value of a multiparametric renal function assessment as a routine tool for evaluating renal function in patients with cirrhosis. A high prevalence of medically actionable renal abnormalities spanning multiple renal function modules, including alterations in glomerular function, salt and solute-free water excretion, and proximal tubule phosphate reabsorption, has been demonstrated in hospitalized patients with cirrhosis.

Executive summary of the KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease: known knowns and known unknowns

The Kidney Disease: Improving Global Outcomes (KDIGO) Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease (CKD) updates the KDIGO 2012 guideline and has been developed with patient partners, clinicians, and researchers around the world, using robust methodology. This update, based on a substantially broader base of evidence than has previously been available, reflects an exciting time in nephrology. New therapies and strategies have been tested in large and diverse populations that help to inform care; however, this guideline is not intended for people receiving dialysis nor those who have a kidney transplant. The document is sensitive to international considerations, CKD across the lifespan, and discusses special considerations in implementation. The scope includes chapters dedicated to the evaluation and risk assessment of people with CKD, management to delay CKD progression and its complications, medication management and drug stewardship in CKD, and optimal models of CKD care. Treatment approaches and actionable guideline recommendations are based on systematic reviews of relevant studies and appraisal of the quality of the evidence and the strength of recommendations which followed the "Grading of Recommendations Assessment, Development, and Evaluation" (GRADE) approach. The limitations of the evidence are discussed. The guideline also provides practice points, which serve to direct clinical care or activities for which a systematic review was not conducted, and it includes useful infographics and describes an important research agenda for the future. It targets a broad audience of people with CKD and their healthcare, while being mindful of implications for policy and payment.

Hepatorenal Syndrome-Novel Insights into Diagnostics and Treatment

Hepatorenal syndrome (HRS) is a disorder associated with cirrhosis and renal impairment, with portal hypertension as its major underlying cause. Moreover, HRS is the third most common cause of acute kidney injury, thus creating a major public health concern. This review summarizes the available information on the pathophysiological implications of HRS. We discuss pathogenesis associated with HRS. Mechanisms such as dysfunction of the circulatory system, bacterial infection, inflammation, impaired renal autoregulation, circulatory, and others, which have been identified as critical pathways for development of HRS, have become easier to diagnose in recent years. Additionally, relatively recently, renal dysfunction biomarkers have been found indicating renal injury, which are involved in the pathophysiology of HRS. This review also summarizes the available information on the management of HRS, focusing on vasoconstrictive drugs, renal replacement therapy, and liver transplant together with currently being investigated novel therapies. Analyzing new discoveries for the underlying causes of this condition assists the general research to improve understanding of the mechanism of pathophysiology and thus prevention of HRS.

Cystatin C as a GFR Estimation Marker in Acute and Chronic Illness: A Systematic Review

Rationale & Objective

Creatinine-based GFR estimating (eGFRcr) equations may be inaccurate in populations with acute or chronic illness. The accuracy of GFR equations that use cystatin C (eGFRcys) or creatinine-cystatin C (eGFRcr-cys) is not well studied in these populations.

Study Design

A systematic review of original articles identified from PubMed and expert sources. Two reviewers screened articles independently and identified those meeting inclusion criteria.

Setting & Study Populations

Adults and children with acute or chronic illness.

Selection Criteria for Studies

Studies published since 2011 that compared performance of eGFRcr, eGFRcys, and eGFRcr-cys relative to measured GFR (mGFR), used standardized assays for creatinine or cystatin C, and used eGFR equations developed using such assays. Studies of ambulatory clinical populations or research studies in populations with only CKD, kidney transplant recipients, only diabetes, kidney donor candidates, and community-based cohorts were excluded.

Data Extraction

Data extracted from full text.

Analytical Approach

Bias and percentages of estimates within 30% of mGFR (P30) of eGFR compared with mGFR were evaluated.

Results

Of the 179 citations, 26 studies met the inclusion criteria: 24 in adults and 2 in children in clinical populations with cancer (n=5), HIV (n=5), cirrhosis (n=3), liver transplant (n=3), heart failure (n=2), neuromuscular diseases (n=1) critical illness (n=5), and obesity (n=2). In general, eGFRcr-cys had greater accuracy than eGFRcr or eGFRcys equations among study populations with cancer, HIV, and obesity, but did not perform consistently better in cirrhosis, liver transplant, heart failure, neuromuscular disease, and critical illness.

Limitations

Participants were selected because of concern for inaccurate eGFRcr, which may bias results. Most studies had small sample sizes, limiting generalizability.

Conclusions

eGFRcr-cys improves GFR estimation in populations with a variety of acute and chronic illnesses, providing indications for cystatin C measurement. Performance was poor in many studies, suggesting the need for more frequent mGFR.

Plain-Language Summary

Kidney function, specifically glomerular filtration rate (GFR), estimated using creatinine (eGFRcr) is often inaccurate in people with acute and chronic illness. The accuracy of estimates using cystatin C alone (eGFRcys) or together with creatinine (eGFRcr-cys) is not well studied in these populations. We conducted a systematic review to address the knowledge gap. Of the 179 papers reviewed, we identified 26 studies in clinical populations with cancer (n=5); HIV (n=5); cirrhosis (n=3); liver transplant (n=3); heart failure (n=2); neuromuscular disease (n=1); critical illness (n=5); and obesity (n=2). In general, eGFRcr-cys improved the GFR estimation in HIV, cancer, and obesity, providing indications for cystatin C measurement. Performance was poor in many studies, suggesting the need for more frequent measured GFR.

Prognostic models in end stage liver disease

Cirrhosis is a major cause of death worldwide, and is associated with significant health care costs. Even if milestones have been recently reached in understanding and managing end-stage liver disease (ESLD), the disease course remains somewhat difficult to prognosticate. These difficulties have already been acknowledged already in the past, when scores instead of single parameters have been proposed as valuable tools for short-term prognosis. These standard scores, like Child Turcotte Pugh (CTP) and model for end-stage liver disease (MELD) score, relying on biochemical and clinical parameters, are still widely used in clinical practice to predict short- and medium-term prognosis. The MELD score, which remains an accurate, easy-to-use, objective predictive score, has received significant modifications over time, in order to improve its performance especially in the liver transplant (LT) setting, where it is widely used as prioritization tool. Although many attempts to improve prognostic accuracy have failed because of lack of replicability or poor benefit with the comparator (often the MELD score or its variants), few scores have been recently proposed and validated especially for subgroups of patients with ESLD, as those with acute-on-chronic liver failure. Artificial intelligence will probably help hepatologists in the near future to fill the current gaps in predicting disease course and long-term prognosis of such patients.

Correlation Between Cystatin C and the Severity of Cardiac Dysfunction in Patients with Systolic Heart Failure

Introduction

To investigate the relationship between cystatin C and cardiac dysfunction severity in patients with systolic heart failure.

Methods

We recruited 100 hospitalized patients with systolic heart failure and 100 age-gender-matched controls. The clinical information of each patient was collected. Blood pressure, heart rate, height, and weight were measured, as were serum concentrations of cholesterol, renal function indices, cystatin C, and B-type natriuretic peptide (BNP). Transthoracic echocardiography was performed on each patient.

Results

Cystatin C and other indices of renal function, such as urea nitrogen, creatinine, and uric acid, were significantly elevated in the serum of patients with heart failure and those with more severe cardiac dysfunction. The stepwise regression analyses showed that cystatin C was positively associated with BNP (β = 0.18, P = 0.04, 95% CI: 21.1 ~ 1420.4) and left atrial diameter (LAD) (β = 0.19, P = 0.04, 95% CI: 0.03 ~ 9.21) and was negatively associated with ejection fraction (β = -0.22, P = 0.023, 95% CI: -12.4 ~ -0.93), while creatinine was only positively correlated with BNP (β = 0.23, P = 0.03, 95% CI: 1.11 ~ 20.7). The Receiver Operating Characteristic (ROC) curves demonstrated significantly more severe cardiac dysfunction (NYHA III/IV) in patients with cystatin C ≥ 0.895mg/L (sensitivity was 83.0%, specificity was 80.9%, AUC = 0.893) and creatinine ≥ 91.5μmol/L (sensitivity was 71.7%, specificity was 70.2%, AUC = 0.764).

Conclusion

Cystatin C was significantly correlated with cardiac structure and function in patients with systolic heart failure, and it was more valuable than creatinine to evaluate the severity of heart failure.

Development of a nomogram for the prediction of acute kidney injury after liver transplantation: a model based on clinical parameters and postoperative cystatin C level

BACKGROUND

Acute kidney injury (AKI) is common after liver transplantation (LT). We developed a nomogram model to predict post-LT AKI.

METHODS

A total of 120 patients were eligible for inclusion in the study. Clinical information was extracted from the institutional electronic medical record system. Blood samples were collected prior to surgery and immediately after surgery. Univariable and multivariate logistic regression were used to identify independent risk factors. Finally, a nomogram was developed based on the final multivariable logistic regression model.

RESULTS

In total, 58 (48.3%) patients developed AKI. Multivariable logistic regression revealed four independent risk factors for post-LT AKI: operation duration [odds ratio (OR) = 1.728, 95% confidence interval (CI) = 1.121-2.663, p = 0.013], intraoperative hypotension (OR = 3.235, 95% CI = 1.316-7.952, p = 0.011), postoperative cystatin C level (OR = 1.002, 95% CI = 1.001-1.004, p = 0.005) and shock (OR = 4.002, 95% CI = 0.893-17.945, p = 0.070). Receiver operating characteristic curve analysis was used to evaluate model discrimination. The area under the curve value was 0.815 (95% CI = 0.737-0.894).

CONCLUSION

The model based on combinations of clinical parameters and postoperative cystatin C levels had a higher predictive performance for post-LT AKI than the model based on clinical parameters or postoperative cystatin C level alone. Additionally, we developed an easy-to-use nomogram based on the final model, which could aid in the early detection of AKI and improve the prognosis of patients after LT.

Update on Assessment of Estimated Glomerular Filtration Rate in Patients With Cirrhosis

Kidney disease is associated with adverse outcomes in patients with cirrhosis including increased post-liver transplantation (LT) mortality. Therefore, diagnosis and staging of kidney disease are critical to timely implementation of treatment and have important implications for transplant eligibility. Serum creatinine (sCr) is a key component of the Model for End-Stage Liver Disease score in LT candidates, and sCr-based estimated glomerular filtration rate (eGFR) values play an important role in determining medical urgency for LT. However, the use of sCr to assess kidney function may be limited in the cirrhotic milieu due to decreased creatinine production, interference of bilirubin with some laboratory assays for sCr, and expansion of the volume of distribution of creatinine. Therefore, conventional eGFR equations perform poorly in patients with cirrhosis and may overestimate kidney function leading to delayed diagnosis of acute kidney injury or lower priority for LT in patients with a truly low glomerular filtration rate. In this review, we will provide an update on the use of sCr for diagnosis and staging of kidney disease in patients with cirrhosis, discuss the limitations of sCr-based eGFR equations, and discuss novel eGFR equations that have been developed in patients with cirrhosis.

Impact of race-independent equations on estimating glomerular filtration rate for the assessment of kidney dysfunction in liver disease

BACKGROUND

Altered hemodynamics in liver disease often results in overestimation of glomerular filtration rate (GFR) by creatinine-based GFR estimating (eGFR) equations. Recently, we have validated a novel eGFR equation based on serum myo-inositol, valine, and creatinine quantified by nuclear magnetic resonance spectroscopy in combination with cystatin C, age and sex (GFR_NMR). We hypothesized that GFR_NMR could improve chronic kidney disease (CKD) classification in the setting of liver disease.

RESULTS

We conducted a retrospective multicenter study in 205 patients with chronic liver disease (CLD), comparing the performance of GFR_NMR to that of validated CKD-EPI eGFR equations, including eGFRcr (based on creatinine) and eGFRcr-cys (based on both creatinine and cystatin C), using measured GFR as reference standard. GFR_NMR outperformed all other equations with a low overall median bias (-1 vs. -6 to 4 ml/min/1.73 m² for the other equations; p < 0.05) and the lowest difference in bias between reduced and preserved liver function (-3 vs. -16 to -8 ml/min/1.73 m² for other equations). Concordant classification by CKD stage was highest for GFR_NMR (59% vs. 48% to 53%) and less biased in estimating CKD severity compared to the other equations. GFR_NMR P30 accuracy (83%) was higher than that of eGFRcr (75%; p = 0.019) and comparable to that of eGFRcr-cys (86%; p = 0.578).

CONCLUSIONS

Addition of myo-inositol and valine to creatinine and cystatin C in GFR_NMR further improved GFR estimation in CLD patients and accurately stratified liver disease patients into CKD stages.

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.

Association Between Kidney Dysfunction Types and Mortality Among Hospitalized Patients with Cirrhosis

BACKGROUND AND AIMS

Kidney dysfunction is associated with increased mortality among patients with cirrhosis. We investigated whether kidney dysfunction types [e.g., acute kidney injury (AKI), chronic kidney disease (CKD), and AKI on CKD] were differentially associated with inpatient mortality.

METHODS

We utilized the nationwide inpatient sample, a nationally representative database, from 2007 to 2014. We included all hospitalizations with previously validated codes for cirrhosis or associated decompensated cirrhosis diagnoses. We defined kidney dysfunction types also from previously validated codes, and we grouped hospitalizations into the following diagnoses: normal, AKI, CKD, and AKI on CKD. Our primary outcome was inpatient mortality.

RESULTS

There were 1,293,779 hospitalizations with cirrhosis sampled in this study. Of these hospitalizations, 849,193 (66%) had normal kidney function, 176,418 (14%) had AKI, 157,600 (12%) had CKD, and 110,568 (9%) had AKI on CKD. We found that the proportion of hospitalizations with AKI, CKD, and AKI on CKD increased significantly throughout the study period (p < 0.001, test for trend for all). Kidney dysfunction type was differentially associated with inpatient mortality, even after adjustment: as compared to those with CKD, normal kidney function: OR 0.75 [95 CI 0.73-0.78], AKI: OR 2.40 [95 CI 2.32-2.48], and AKI on CKD: OR 1.66 [95 CI 1.60-1.72].

DISCUSSION

Using a nationally representative cohort of all hospitalizations with cirrhosis, our study highlights that the burden of kidney dysfunction, especially AKI, among hospitalizations with cirrhosis is rising, and the inclusion of kidney dysfunction type may be an opportunity to improve prognostication.

"Beyond MELD" - Emerging strategies and technologies for improving mortality prediction, organ allocation and outcomes in liver transplantation

In this review article, we discuss the model for end-stage liver disease (MELD) score and its dual purpose in general and transplant hepatology. As the landscape of liver disease and transplantation has evolved considerably since the advent of the MELD score, we summarise emerging concepts, methodologies, and technologies that may improve mortality prognostication in the future. Finally, we explore how these novel concepts and technologies may be incorporated into clinical practice.

Hepatorenal Syndrome: Definitions, Diagnosis, and Management

Hepatorenal syndrome (HRS) is a hemodynamically driven process mediated by renal dysregulation and inflammatory response. Albumin, antibiotics, and β-blockers are among therapies that have been studied in HRS prevention. There are no Food and Drug Administration-approved treatments for HRS although multiple liver societies have recommended terlipressin as first-line pharmacotherapy. Renal replacement therapy is the primary modality used to bridge to definitive therapy with orthotopic liver transplant or simultaneous liver-kidney transplant. Advances in our understanding of HRS pathophysiology and emerging therapeutic modalities are needed to change outcomes for this vulnerable population.

Race Adjustment in eGFR Equations Does Not Improve Estimation of Acute Kidney Injury Events in Patients with Cirrhosis

BACKGROUND

Accuracy of glomerular filtration rate estimating (eGFR) equations has significant implications in cirrhosis, potentially guiding simultaneous liver kidney allocation and drug dosing. Most equations adjust for Black race, partially accounted for by reported differences in muscle mass by race. Patients with cirrhosis, however, are prone to sarcopenia which may mitigate such differences. We evaluated the association between baseline eGFR and incident acute kidney injury (AKI) in patients with cirrhosis with and without race adjustment.

METHODS

We conducted a retrospective national cohort study of veterans with cirrhosis. Baseline eGFR was calculated using multiple eGFR equations including Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI), both with and without race adjustment. Poisson regression was used to investigate the association between baseline eGFR and incident AKI events per International Club of Ascites criteria.

RESULTS

We identified 72,267 patients with cirrhosis, who were 97.3% male, 57.8% white, and 19.7% Black. Over median follow-up 2.78 years (interquartile range 1.22-5.16), lower baseline eGFR by CKD-EPI was significantly associated with higher rates of AKI in adjusted models. For all equations this association was minimally impacted when race adjustment was removed. For example, removal of race adjustment from CKD-EPI resulted in a 0.1% increase in the association between lower eGFR and higher rate of AKI events per 15 mL/min/1.73 m² change (p < 0.001).

CONCLUSIONS

Race adjustment in eGFR equations did not enhance AKI risk estimation in patients with cirrhosis. Further study is warranted to assess the impacts of removing race from eGFR equations on clinical outcomes and policy.

Estimated glomerular filtration rate by formulas in patients with cirrhosis: An unreliable procedure

BACKGROUND & AIMS

In cirrhosis, the reliability of formulas that estimate renal function, either those specifically developed in this population or the classic equations, has not been properly quantified. We studied the agreement between estimated (eGFR) and measured glomerular filtration rate (mGFR) in cirrhosis.

METHODS

Renal function was estimated with 56 formulas including specific equations: Glomerular Filtration Rate Assessment in Liver Disease (GRAIL), Royal Free Hospital Cirrhosis (RFHC) and Mindikoglu-eGFR, and measured with a gold standard procedure; plasma clearance of iohexol using dried blood spots sampling in a group of cirrhotics. The agreement eGFR-mGFR was evaluated with specific tests: total deviation index (TDI), concordance correlation coefficient (CCC) and coverage probability (CP). We defined acceptable agreement as values: TDI < 10%, CCC ≥ 0.9 and CP > 90%.

RESULTS

A total of 146 patients (age 65 ± 9 years, 81% male) were evaluated; 61 (42%) Child A, 67 (46%) Child B and 18 (12%) Child C. Median MELD-Na was 14 (9-15). The agreement between eGFR and mGFR was poor: TDI averaged was of 73% (90% of the estimations ranged from ±73% of mGFR); CCC averaged was 0.7 indicating low concordance and CP averaged 22% indicating that 78% of the estimations have an error > 10%. Specific formulas showed also poor agreement: TDI was 82%, 70% and 37% for the GRAIL, RFHC and Mindikoglu equations, respectively.

CONCLUSIONS

Overall, formulas poorly estimated renal function in cirrhotic patients. Specific formulas designed for cirrhosis did not outperform classic equations. eGFR must be considered with caution in cirrhotic patients.

Management of Diabetes in Candidates for Liver Transplantation and in Transplant Recipients

Diabetes is common in patients waitlisted for liver transplantation because of end-stage liver disease or hepatocellular cancer as well as in posttransplant phase (posttransplantation diabetes mellitus). In both conditions, the presence of diabetes severely affects disease burden and long-term clinical outcomes; careful monitoring and appropriate treatment are pivotal to reduce cardiovascular events and graft and recipients' death. We thoroughly reviewed the epidemiology of diabetes in the transplant setting and the different therapeutic options, from lifestyle intervention to antidiabetic drug use-including the most recent drug classes available-and to the inclusion of bariatric surgery in the treatment cascade. In waitlisted patients, the old paradigm that insulin should be the treatment of choice in the presence of severe liver dysfunction is no longer valid; novel antidiabetic agents may provide adequate glucose control without the risk of hypoglycemia, also offering cardiovascular protection. The same evidence applies to the posttransplant phase, where oral or injectable noninsulin agents should be considered to treat patients to target, limiting the impact of disease on daily living, without interaction with immunosuppressive regimens. The increasing prevalence of liver disease of metabolic origin (nonalcoholic fatty liver) among liver transplant candidates, also having a higher risk of noncirrhotic hepatocellular cancer, is likely to accelerate the acceptance of new drugs and invasive procedures, as suggested by international guidelines. Intensive lifestyle intervention programs remain however mandatory, both before and after transplantation. Achievement of adequate control is mandatory to increase candidacy, to prevent delisting, and to improve long-term outcomes.

Clinical application and pharmacological mechanism of Wuling powder in the treatment of ascites: A systematic review and network pharmacological analysis

Ascites is one of the common complications in patients with decompensated liver cirrhosis and liver cancer. Wuling powder (WLP) is a classic prescription for the treatment of water retention caused by bladder gasification. It is also widely used in the treatment of ascites. This systematic review aimed to evaluate the clinical efficacy of WLP and determine its effective chemical components based on a large number of related pieces of literature. The pharmacological effects and chemical constituents of WLP were summarized. Besides, the clinical research status of WLP in the treatment of ascites caused by liver cancer and cirrhosis was analyzed. The key targets and pathways of WLP in the treatment of ascites based on network pharmacology analysis were also discussed. Furthermore, the core components and core targets of WLP in the treatment of ascites using molecular docking were verified and the interaction sites were predicted, to provide a theoretical and scientific basis for the clinical application of WLP.

Estimating Glomerular Filtration Rate in Cirrhosis Using Creatinine-Based and Cystatin C-Based Equations: Systematic Review and Meta-Analysis

Accurate estimation of kidney function in cirrhosis is crucial for prognosis and decisions regarding dual-organ transplantation. We performed a systematic review/meta-analysis to assess the performance of creatinine-based and cystatin C (CysC)-based eGFR equations compared with measured GFR (mGFR) in patients with cirrhosis. A total of 25 studies (n = 4565, 52.0 years, 37.0% women) comprising 18 equations met the inclusion criteria. In all GFR equations, the creatinine-based equations overestimated GFR (standardized mean difference, SMD, 0.51; 95% confidence interval [CI], 0.31-0.71) and CysC-based equations underestimated GFR (SMD, -0.3; 95% CI, -0.60 to -0.02). Equations based on both creatinine and CysC were the least biased (SMD, -0.14; 95% CI, -0.46 to 0.18). Chronic kidney disease-Epi-serum creatinine-CysC (CESC) was the least biased but had low precision and underestimated GFR by -3.6 mL/minute/1.73 m² (95% CI, -17.4 to 10.3). All equations significantly overestimated GFR (+21.7 mL/minute/1.73 m² ; 95% CI, 17.7-25.7) at GFR <60 mL/minute/1.73 m² ; of these, chronic kidney disease-Epi-CysC (10.3 mL/minute/1.73 m² ; 95% CI, 2.1-18.4) and GFR Assessment in Liver Disease (12.6 mL/minute/1.73 m² ; 95% CI, 7.2-18.0) were the least biased followed by Royal Free Hospital (15 mL/minute/1.73 m² ; 95% CI, 5.5-24.6) and Modification of Diet in Renal Disease 6 (15.7 mL/minute/1.73 m² ; 95% CI, 10.6-20.8); however, there was an overlap in the precision of estimates, and the studies were limited. In ascites, overestimation of GFR was common (+8.3 mL/minute/1.73 m² ; 95% CI, -3.1 to 19.7). However, overestimation of GFR by 10 to 20 mL/minute/1.73m² is common in patients with cirrhosis with most equations in ascites and/or kidney dysfunction. A tailored approach is required especially for decisions regarding dual-organ transplantation.

Post-Liver Transplant Acute Kidney Injury

Acute kidney injury (AKI) is a common condition following liver transplantation (LT). It negatively impacts patient outcomes by increasing the chances of developing chronic kidney disease and reducing graft and patient survival rates. Multiple definitions of AKI have been proposed and used throughout the years, with the International Club of Ascites definition being the most widely now used for patients with cirrhosis. Multiple factors are associated with the development of post-LT AKI and can be categorized into pre-LT comorbidities, donor and recipient characteristics, operative factors, and post-LT factors. Many of these factors can be optimized in an attempt to minimize the risk of AKI occurring and to improve renal function if AKI is already present. A special consideration during the post-LT phase is needed for immunosuppression as certain immunosuppressive medications can be nephrotoxic. The calcineurin inhibitor tacrolimus (TAC) is the mainstay of immunosuppression but can result in AKI. Several strategies including use of the monoclonoal antibody basilixamab to allow for delayed initiation of tacrolimus therapy and minimization through combination and minimization or elimination of TAC through combination with mycophenolate mofetil or mammalian target of rapamycin inhibitors have been implemented to reverse and avoid AKI in the post-LT setting. Renal replacement therapy may ultimately be required to support patients until recovery of AKI after LT. Overall, by improving renal function in post-LT patients with AKI, outcomes can be improved.

Current knowledge about biomarkers of acute kidney injury in liver cirrhosis

Acute kidney injury (AKI) is common in advanced cirrhosis. Prerenal azotemia, hepatorenal syndrome, and acute tubular necrosis are the main causes of AKI in patients with cirrhosis. Evaluation of renal function and differentiation between functional and structural kidney injury are important issues in the management of cirrhosis. However, AKI in cirrhosis exists as a complex clinical spectrum rather than concrete clinical entity. Based on current evidence, changes in serum creatinine (Cr) levels remain the most appropriate standard for defining AKI in cirrhosis. However, serum Cr has a limited role in assessing renal function in this population. This review examines previous studies that investigated the ability of recent biomarkers for AKI in cirrhosis from the perspective of earlier and accurate diagnosis, classification of AKI phenotype, and prediction of clinical outcomes. Serum cystatin C and urine neutrophil gelatinase-associated lipocalin have been extensively studied in cirrhosis, and have facilitated improved diagnosis and prognosis prediction in patients with AKI. In addition, urine N-acetyl-β-D-glucosaminidase, interleukin 18, and kidney injury molecule 1 are other promising biomarkers for advanced cirrhosis. However, the clinical significance of these markers remains unclear because there are no cut-off values defining the normal range and differentiating phenotypes of AKI. In addition, AKI has been defined in terms of serum Cr, and renal biopsy-the gold standard-has not been carried out in most studies. Further discovery of innovate biomarkers and incorporation of various markers could improve the diagnosis and prognosis prediction of AKI, and will translate into meaningful improvements in patient outcomes.

Assessment of kidney function: clinical indications for measured GFR

In the vast majority of cases, glomerular filtration rate (GFR) is estimated using serum creatinine, which is highly influenced by age, sex, muscle mass, body composition, severe chronic illness and many other factors. This often leads to misclassification of patients or potentially puts patients at risk for inappropriate clinical decisions. Possible solutions are the use of cystatin C as an alternative endogenous marker or performing direct measurement of GFR using an exogenous marker such as iohexol. The purpose of this review is to highlight clinical scenarios and conditions such as extreme body composition, Black race, disagreement between creatinine- and cystatin C-based estimated GFR (eGFR), drug dosing, liver cirrhosis, advanced chronic kidney disease and the transition to kidney replacement therapy, non-kidney solid organ transplant recipients and living kidney donors where creatinine-based GFR estimation may be invalid. In contrast to the majority of literature on measured GFR (mGFR), this review does not include aspects of mGFR for research or public health settings but aims to reach practicing clinicians and raise their understanding of the substantial limitations of creatinine. While including cystatin C as a renal biomarker in GFR estimating equations has been shown to increase the accuracy of the GFR estimate, there are also limitations to eGFR based on cystatin C alone or the combination of creatinine and cystatin C in the clinical scenarios described above that can be overcome by measuring GFR with an exogenous marker. We acknowledge that mGFR is not readily available in many centres but hope that this review will highlight and promote the expansion of kidney function diagnostics using standardized mGFR procedures as an important milestone towards more accurate and personalized medicine.

Advances in management of hepatorenal syndrome

PURPOSE OF REVIEW

Hepatorenal syndrome (HRS) is encountered frequently in patients with end-stage liver disease and remains an important cause of morbidity and mortality in this patient population. This review will focus and provide updates on pathophysiology, assessment of kidney function, new definitions, and treatment and prevention of HRS.

RECENT FINDINGS

Pathophysiology of HRS has been elucidated more recently and in addition to hemodynamic changes, the role of systemic inflammatory response contributes significantly to this process. Assessment of kidney function in patients with liver cirrhosis remains challenging. Novel glomerular filtration rate equations have been developed in patients with liver disease to better estimate kidney function and changes made in the definition of acute kidney injury (AKI), which are more aligned with KDIGO criteria for AKI. Vasoconstrictors, especially terlipressin, along with albumin remain the mainstay of pharmacological treatment of HRS-AKI. Biomarkers have been useful in differentiating ATN from HRS at an early stage.

SUMMARY

HRS remains a significant cause of morbidity and mortality for patients with end-stage liver disease. Newer understanding of mechanisms in development and pathophysiology of HRS have helped with elucidation of the disease process.

Management of the major complications of cirrhosis: Beyond guidelines

Along with a growing understanding of the pathophysiology of cirrhosis and its complications, new therapies and management strategies have emerged in recent years. Many of these advances have helped inform the current EASL clinical practice guidelines¹ on the management of some of the key complications of cirrhosis, such as ascites, variceal bleeding and infection. However, there are still some aspects of management where the evidence base is less clear, and/or where opinions amongst practitioners remain divided. Some of these more controversial areas are explored in this section, wherein we present evidence culminating in a suggested management approach based on expert opinion and extending beyond the current guidelines.

Position paper on liver and kidney diseases from the Italian Association for the Study of Liver (AISF), in collaboration with the Italian Society of Nephrology (SIN)

Liver and kidney are strictly connected in a reciprocal manner, in both the physiological and pathological condition. The Italian Association for the Study of Liver, in collaboration with the Italian Society of Nephrology, with this position paper aims to provide an up-to-date overview on the principal relationships between these two important organs. A panel of well-recognized international expert hepatologists and nephrologists identified five relevant topics: 1) The diagnosis of kidney damage in patients with chronic liver disease; 2) Acute kidney injury in liver cirrhosis; 3) Association between chronic liver disease and chronic kidney disease; 4) Kidney damage according to different etiology of liver disease; 5) Polycystic kidney and liver disease. The discussion process started with a review of the literature relating to each of the five major topics and clinical questions and related statements were subsequently formulated. The quality of evidence and strength of recommendations were graded according to the GRADE system. The statements presented here highlight the importance of strong collaboration between hepatologists and nephrologists for the management of critically ill patients, such as those with combined liver and kidney impairment.

Silymarin mitigates bile duct obstruction-induced cholemic nephropathy

Bile duct obstruction or cholestasis can occur by several diseases or xenobiotics. Cholestasis and the accumulation of the bile constituents in the liver primarily damage this organ. On the other hand, extrahepatic organs are also affected by cholestasis. The kidney is the most affected tissue during cholestatic liver injury. Cholestasis-associated renal injury is known as cholemic nephropathy (CN). Several lines of evidence specify the involvement of oxidative stress and mitochondrial impairment in the pathogenesis of CN. The current study aimed to assess the role of silymarin as a potent antioxidant on CN-induced oxidative stress and mitochondrial dysfunction in the kidney. Bile duct ligated (BDL) rats were treated with silymarin (10 and 100 mg/kg, oral) for seven consecutive days. A significant increase in reactive oxygen species (ROS), lipid peroxidation, protein carbonylation, and oxidized glutathione (GSSG) levels were evident in the kidney of BDL animals. Moreover, reduced glutathione (GSH) content and total antioxidant capacity were significantly decreased in the kidney of cholestatic rats. Mitochondrial depolarization, decreased mitochondrial dehydrogenases activity, mitochondrial permeabilization, and depleted ATP stores were detected in the kidney mitochondria isolated from BDL animals. Kidney histopathological alterations, as well as serum and urine levels of renal injury biomarkers, were also significantly different in the BDL group. It was found that silymarin treatment significantly ameliorated CN-induced renal injury. The antioxidant effects of silymarin and its positive impact on mitochondrial indices seem to play a significant role in its renoprotective effects during cholestasis.

Nonalcoholic Fatty Liver Disease and Diabetes Mellitus Are Associated With Post-Transjugular Intrahepatic Portosystemic Shunt Renal Dysfunction: An Advancing Liver Therapeutic Approaches Group Study

Transjugular intrahepatic portosystemic shunt (TIPS) is an effective intervention for portal hypertensive complications, but its effect on renal function is not well characterized. Here we describe renal function and characteristics associated with renal dysfunction at 30 days post-TIPS. Adults with cirrhosis who underwent TIPS at 9 hospitals in the United States from 2010 to 2015 were included. We defined "post-TIPS renal dysfunction" as a change in estimated glomerular filtration rate (ΔeGFR) ≤-15 and eGFR ≤ 60 mL/min/1.73 m² or new renal replacement therapy (RRT) at day 30. We identified the characteristics associated with post-TIPS renal dysfunction by logistic regression and evaluated survival using adjusted competing risk regressions. Of the 673 patients, the median age was 57 years, 38% of the patients were female, 26% had diabetes mellitus, and the median MELD-Na was 17. After 30 days post-TIPS, 66 (10%) had renal dysfunction, of which 23 (35%) required new RRT. Patients with post-TIPS renal dysfunction, compared with those with stable renal function, were more likely to have nonalcoholic fatty liver disease (NAFLD; 33% versus 17%; P = 0.01) and comorbid diabetes mellitus (42% versus 24%; P = 0.001). Multivariate logistic regressions showed NAFLD (odds ratio [OR], 2.04; 95% confidence interval [CI], 1.00-4.17; P = 0.05), serum sodium (Na; OR, 1.06 per mEq/L; 95% CI, 1.01-1.12; P = 0.03), and diabetes mellitus (OR, 2.04; 95% CI, 1.16-3.61; P = 0.01) were associated with post-TIPS renal dysfunction. Competing risk regressions showed that those with post-TIPS renal dysfunction were at a higher subhazard of death (subhazard ratio, 1.74; 95% CI, 1.18-2.56; P = 0.01). In this large, multicenter cohort, we found NAFLD, diabetes mellitus, and baseline Na associated with post-TIPS renal dysfunction. This study suggests that patients with NAFLD and diabetes mellitus undergoing TIPS evaluation may require additional attention to cardiac and renal comorbidities before proceeding with the procedure.

Hepatorenal Syndrome

Development of acute kidney injury in patients with chronic liver disease is common and portends a poor prognosis. Diagnosis remains challenging, as traditional markers, such as serum creatinine, are not reliable. Recent development of novel biomarkers may assist with this. Pathophysiology of this condition is multifactorial, relating to physiologic changes associated with portal hypertension, kidney factors, and systemic inflammatory response. Mainstay of treatment remains use of vasoconstrictors along with albumin. Recent guidelines streamline the selection of patients that will require simultaneous liver and kidney transplantation. Posttransplant kidney injury is common relating to multiple factors.

[Acute kidney injury following acute pancreatitis (AP-AKI): Definition, Pathophysiology, Diagnosis and Therapy]

Acute pancreatitis (AP) is the most frequent gastrointestinal cause for hospitalization and one of the leading causes of in-hospital deaths. Severe acute pancreatitis is often associated with multiorgan failure and especially with acute kidney injury (AKI). AKI can develop early or late in the course of the disease and is a strong determinator of outcome. The mortality in the case of dialysis-dependent AKI and acute pancreatitis raises exponentially in the affected patients. AP-induced AKI (AP-AKI) shows many similarities but also distinct differences to other causes of AKI occurring in the intensive care unit setting. The knowledge of the exact pathophysiology can help to adjust, control and improve therapeutic approaches to the disease. Unfortunately, there are only a few studies dealing with AP and AKI.In this review, we discuss recent data about pathogenesis, causes and management of AP-AKI in patients with severe acute pancreatitis and exploit in this regard the diagnostic and prognostic potential of respective newer serum and urine markers.

Serum Cystatin C Concentrations in Patients with Graves' Ophthalmopathy

Purpose

To evaluate the concentration of serum cystatin C (CysC) in patients with Graves’ ophthalmopathy (GO) and the usability of the serum CysC concentrations in the follow-up of the disease.

Methods

Thirty patients with GO and 30 healthy age-matched volunteers were included in this cross-sectional study. GO was diagnosed based on the European Group on Graves’ Orbitopathy consensus. Serum thyroid-stimulating hormone, free triiodothyronine, free thyroxine, and CysC concentrations were measured in the participants. The serum CysC concentrations were compared between patients with GO and controls. Patients with GO were subdivided into hyperthyroid and euthyroid patients, and their serum CysC concentrations were compared. In addition, the CysC concentrations in hyperthyroid and euthyroid patients with GO were compared separately with those of healthy subjects. Kruskal-Wallis test and Student’s t-test were used for statistical evaluation.

Results

The mean serum CysC concentrations in GO patients and controls were 1.04 ± 0.36 and 0.74 ± 0.09 mg/L, respectively. There was a statistically significant difference in the serum CysC concentrations between patients with GO and control subjects (p < 0.001). Fifteen patients had hyperthyroid status, and 15 patients had euthyroid status. The mean serum CysC concentrations in hyperthyroid and euthyroid patients with GO were 1.35 ± 0.22 and 0.72 ± 0.13 mg/L, respectively. Serum CysC concentrations were significantly higher in hyperthyroid patients than in euthyroid patients (p = 0.001). In addition, hyperthyroid patients had significantly higher serum CysC concentrations than healthy subjects. Among patients with GO, 21 and nine had mild and moderate-to-severe GO, respectively. Active and inactive GO were observed in eight and 22 patients, respectively.

Conclusions

The serum CysC concentrations in hyperthyroid patients were higher than those in healthy subjects. Moreover, hyperthyroid patients had higher serum CysC concentrations than euthyroid patients. Further studies with a larger sample size are needed to confirm these results.

Prediction of Liver Prognosis from Pre-Transplant Renal Function Adjusted by Diuretics and Urinary Abnormalities in Adult-to-Adult Living Donor Liver Transplantation

BACKGROUND Renal function is strongly associated with patient survival after liver transplantation. However, the estimated glomerular filtration rate (eGFR) after liver transplantation changes, especially in patients who receive diuretics or have urinary abnormalities. We aimed to elucidate how adjusting for these factors affecting eGFR predicted liver graft prognosis. MATERIAL AND METHODS This retrospective study included patients who underwent adult-to-adult living donor liver transplantation (LDLT) between 2000 and 2017. The factors affecting eGFR were assessed, and the association between eGFR and prognosis was investigated using Cox regression models after adjusting for factors affecting renal function. RESULTS We enrolled 244 patients. The median observation period was 4.6 years, and 88 patients reached graft loss or death with a functioning graft. One year after transplantation, 193 patients were living, and one-third of these showed improved eGFR; most of the patients with improved eGFR had taken diuretics before transplantation. A Cox regression model adjusted for the classical risk factors showed that donor age (P<0.001) and lower eGFR (P=0.02) were the independent risk factors associated with poor prognosis. After adjusting for diuretics and urinary abnormalities, eGFR was more strongly associated with liver graft prognosis (P=0.003). CONCLUSIONS Pre-transplant eGFR was associated with prognosis following LDLT and had a stronger effect on prognosis after adjusting for factors affecting eGFR.

Discovery and Validation of a Biomarker Model (PRESERVE) Predictive of Renal Outcomes After Liver Transplantation

BACKGROUND AND AIMS

A high proportion of patients develop chronic kidney disease (CKD) after liver transplantation (LT). We aimed to develop clinical/protein models to predict future glomerular filtration rate (GFR) deterioration in this population.

APPROACH AND RESULTS

In independent multicenter discovery (CTOT14) and single-center validation (BUMC) cohorts, we analyzed kidney injury proteins in serum/plasma samples at month 3 after LT in recipients with preserved GFR who demonstrated subsequent GFR deterioration versus preservation by year 1 and year 5 in the BUMC cohort. In CTOT14, we also examined correlations between serial protein levels and GFR over the first year. A month 3 predictive model was constructed from clinical and protein level variables using the CTOT14 cohort (n = 60). Levels of β-2 microglobulin and CD40 antigen and presence of hepatitis C virus (HCV) infection predicted early (year 1) GFR deterioration (area under the curve [AUC], 0.814). We observed excellent validation of this model (AUC, 0.801) in the BUMC cohort (n = 50) who had both early and late (year 5) GFR deterioration. At an optimal threshold, the model had the following performance characteristics in CTOT14 and BUMC, respectively: accuracy (0.75, 0.8), sensitivity (0.71, 0.67), specificity (0.78, 0.88), positive predictive value (0.74, 0.75), and negative predictive value (0.76, 0.82). In the serial CTOT14 analysis, several proteins, including β-2 microglobulin and CD40, correlated with GFR changes over the first year.

CONCLUSIONS

We have validated a clinical/protein model (PRESERVE) that early after LT can predict future renal deterioration versus preservation with high accuracy. This model may help select recipients at higher risk for subsequent CKD for early, proactive renal sparing strategies.

Chronic Kidney Disease in Liver Transplant Candidates: A Rising Burden Impacting Post-Liver Transplant Outcomes

The burden of chronic kidney disease (CKD) is rising among patients with cirrhosis, though it is not known what impact this has had on outcomes after liver transplantation (LT). All patients listed for LT in the United States between 2002 and 2017 were analyzed, excluding those listed with Model for End-Stage Liver Disease (MELD) exceptions. The primary outcome was post-LT mortality. We defined pre-LT CKD as an estimated glomerular filtration rate <60 mL/minute for 90 days or ≥42 days of hemodialysis. Cox regression determined the association between pre-LT CKD and post-LT mortality. Of 78,640 LT candidates, the proportion with CKD among LT recipients increased from 7.8% in 2002 to 14.6% in 2017 (test for trend, P < 0.001). Among the 39,719 LT recipients, pre-LT CKD was significantly associated with post-LT mortality (hazard ratio [HR], 1.16; P < 0.001) even after adjusting for donor risk index (DRI), age, MELD, etiology, hepatic encephalopathy, simultaneous liver-kidney transplantation (SLKT), and diabetes. There was no mediating influence of SLKT on the effect of pre-LT CKD on post-LT survival (P > 0.05). Therefore, pre-LT CKD has a deleterious impact on post-LT outcomes, which is an impact that is not mediated through SLKT. These findings highlight the need for the identification of CKD when preventative measures are possible.

Hepatorenal Syndrome Type 1: Current Challenges And Future Prospects

Renal dysfunction represents a dreadful complication of advanced liver cirrhosis. In addition to the traditional types of acute kidney injury (AKI) that can occur in the general population, cirrhotics might experience a different kind of renal dysfunction, called hepatorenal syndrome (HRS). The exact definition of HRS is a functional renal dysfunction caused by overactivity of the endogenous vasoactive systems (in particular intrarenal circulation) which lead to reduced renal perfusion. Type I HRS (HRS-1) is characterized by an abrupt deterioration in renal function (in less than 2 weeks), defined by a doubling of baseline sCr to >2.5 mg/dL or a 50% reduction in the initial 24 hrs creatinine clearance to <20 mL/min. Frequent precipitating events leading to HRS-1 are bacterial infections, gastrointestinal hemorrhage, or large-volume paracentesis without adequate albumin administration as well as massive diuretic use. In 2015, the international club of ascites (ICA) revised the definitions and recommendations concerning HRS. The revised definition allows to adopt effective pharmacological therapy based on albumin and vasoconstrictors in an earlier stage thus not influenced anymore by a rigid sCr cut-off value as by the previous definition of HRS-1. The aim of this article was to provide an updated overview of the latest advancements in the field of hepatorenal syndrome and of the recent amendments of the previous definitions of kidney injury in cirrhotic patients.

Changes in Simultaneous Liver-kidney Transplant Allocation Policy May Impact Postliver Transplant Outcomes

BACKGROUND

Previous simultaneous liver-kidney (SLK) transplant allocation was based on serum creatinine, a metric that disadvantaged women relative to men. A recent SLK transplant policy change uses estimated glomerular filtration rate (eGFR), which accounts for sex-based differences in creatinine.

METHODS

To understand the impact of this new policy, we analyzed nonstatus 1 adults listed for liver transplantation (LT) from May 2007 to July 2014, excluding those with exceptions. We defined patients who met the new SLK policy as having an eGFR <60 mL/min for 90 days, with a final eGFR <30 mL/min.

RESULTS

Of 40979 candidates, 1683 would have met only the new criteria (N-SLK), 2452 would have met only the old criteria (O-SLK), and 1878 would have met both criteria (B-SLK). Compared to those in the B-SLK or O-SLK groups, those in the N-SLK group were significantly more likely to be female (52% versus 36% versus 39%, P < 0.001). Cox-regression analysis demonstrated that in adjusted analysis those in the N-SLK group were significantly less likely to die postliver transplant (hazard ratio [HR], 0.0; P < 0.001). Further, in Cox regression subgroup analyses, both in women (HR 0.04; P < 0.001) and in men (HR, 0.02, P < 0.001) those in the N-SLK group who underwent liver transplant were significantly less likely to die postliver transplant, even after adjustment for confounders.

CONCLUSIONS

We anticipate that implementation of the new SLK policy will increase the proportion of women and decrease the proportion of men who are listed for SLK but may not improve posttransplant survival. Our data highlight the need for monitoring of SLK outcomes after implementation of the new policy.

Association Between Renal Function Pattern and Mortality in Patients With Cirrhosis

BACKGROUND & AIMS

Renal dysfunction increases risk of death for patients with cirrhosis. We investigated whether mortality differs significantly among patients with acute kidney injury (AKI), chronic kidney disease (CKD), and both.

METHODS

We performed a retrospective analysis of all non-status 1 adults on the waitlist for liver transplantation for at least 90 days, collected from the Organ Procurement and Transplantation Network registry from July 1, 2007 through July 1, 2014. We assigned patients to groups of AKI (an increase of ≥0.3 mg/dL or ≥50% in serum creatinine in the last 7 days or fewer than 72 days of hemodialysis), CKD (an estimated glomerular filtration rate <60 ml/min/1.73 m² for 90 days with a final rate ≥30 ml/min/1.73 m² or ≥72 days of hemodialysis), AKI and CKD (meet both definitions), or normal (meet neither definition). We performed competing risk analyses to associate patterns of renal dysfunction with waitlist mortality, accounting for liver transplantation, with renal pattern as a time-dependent covariate. Logistic regression for 6-month mortality determined the added benefit of including renal function pattern in the assessment.

RESULTS

There were 22,680 patients in the cohort; they spent a median 1.6 years (range, 0.7-3.1 years) on the waitlist and a median 5 years (range, 2-9 years) undergoing assessments of renal function. In competing risk analysis, even after adjusting for confounders including final model for end-stage liver disease sodium (MELD-Na) scores, the pattern of renal function was significantly associated with waitlist mortality: AKI and CKD (subhazard ratio [SHR], 2.86; 95% CI, 2.65-3.10), AKI (SHR, 2.42; 95% CI 2.22-2.64), CKD (SHR, 1.56; 95% CI, 1.45-1.67) compared with normal. The area under the curve values, based on MELD-Na score at time of placement on the waitlist, were 0.80 with renal function pattern and 0.71 without (P < .001).

CONCLUSION

In competing risk analysis, even after adjusting for confounders including final MELD-Na score, we found the pattern of renal dysfunction to associate with mortality in patients with cirrhosis. Including information on type of renal dysfunction could improve risk analysis.

Pretransplant renal function evaluated by serum cystatin C was associated with mortality after liver transplantation: a single-center experience

Background

In the model for end-stage liver disease (MELD) score, renal function was well thought to be associated with the prognosis of liver recipients. Serum cystatin C (CystC)-based equations were considered more accurate for calculating estimated glomerular filtration rate (eGFR) than creatinine (Pcr) based equations. Thus, we aimed to assess the association between eGFR estimated by chronic kidney disease epidemiology collaboration (CKD-EPI)-CystC equation and post-transplantation mortality.

Methods

From January 2015 to January 2018, prior to liver transplantation (LT) and other clinical parameters, CystC was collected in all 307 consecutive patients who underwent LT at our center. Patients were divided into four groups according to the Kidney Disease Outcomes Quality Initiative (KDOQI) classification.

Results

Based on CKD-EPI-CystC and the KDOQI classification, 117 patients (38.1%) were stage I, 76 (24.8%) were stage II, 85 (27.7%) were stage III, and 29 (9.4%) were stage IV-V. After univariate and multivariate analysis, MELD score [hazard ratio (HR) =1.035; 95% confidence interval (CI), 1.006-1.066; P=0.018], associated HCC (HR =2.314; 95% CI, 1.253-4.273; P=0.007), and KDOQI stage III (HR =1.850; 95% CI, 1.001-3.419; P=0.049), and stage IV-V (HR =3.915; 95% CI, 1.843-8.316; P<0.001) according to CKD-EPI-CystC equation were confirmed to be independent prognostic factors for post-LT survival.

Conclusions

The pretransplant renal function evaluated by serum CystC was associated with mortality after LT and could be used for predicting post-transplant survival.

A Model for Glomerular Filtration Rate Assessment in Liver Disease (GRAIL) in the Presence of Renal Dysfunction

Estimation of glomerular filtration rate (eGFR) in patients with liver disease is suboptimal in the presence of renal dysfunction. We developed a model for GFR assessment in liver disease (GRAIL) before and after liver transplantation (LT). GRAIL was derived using objective variables (creatinine, blood urea nitrogen, age, gender, race, and albumin) to estimate GFR based on timing of measurement relative to LT and degree of renal dysfunction (www.bswh.md/grail). The measured GFR (mGFR) by iothalamate clearance (n = 12,122, 1985-2015) at protocol time points before/after LT was used as reference. GRAIL was compared with the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) and Modification of Diet in Renal Disease (MDRD-4, MDRD-6) equations for mGFR < 30 mL/min/1.73 m² . Prediction of development of chronic kidney disease (mGFR < 20 mL/min/1.73 m² , initiation of chronic dialysis) and listing or receipt of kidney transplantation within 5 years was examined in internal cohort (n = 785) and external validation (n = 68,217, 2001-2015). GRAIL had less bias and was more accurate and precise as compared with CKD-EPI, MDRD-4, and MDRD-6 at time points before/after LT for low GFR. For mGFR < 30 mL/min/1.73 m² , the median difference (eGFR-mGFR) was GRAIL: 5.24 (9.65) mL/min/1.73 m² as compared with CKD-EPI: 8.70 (18.24) mL/min/1.73 m² , MDRD-4: 8.82 (17.38) mL/min/1.73 m² , and MDRD-6: 6.53 (14.42) mL/min/1.73 m² . Before LT, GRAIL correctly classified 75% as having mGFR < 30 mL/min/1.73 m² versus 36.1% (CKD-EPI), 36.1% (MDRD-4), and 52.8% (MDRD-6) (P < 0.01). An eGFR < 30 mL/min/1.73 m² by GRAIL predicted development of CKD (26.9% versus 4.6% CKD-EPI, 5.9% MDRD-4, and 10.5% MDRD-6) in center data and needing kidney after LT (48.3% versus 22.0% CKD-EPI versus 23.1% MDRD-4 versus 48.3% MDRD-6, P < 0.01) in national data within 5 years after LT. Conclusion: GRAIL may serve as an alternative model to estimate GFR among patients with liver disease before and after LT at low GFR.

Comparing Simultaneous Liver-Kidney Transplant Strategies: A Modified Cost-Effectiveness Analysis

BACKGROUND

The proportion of patients with kidney failure at time of liver transplantation is at a historic high in the United States. The optimal timing of kidney transplantation with respect to the liver transplant is unknown.

METHODS

We used a modified cost-effectiveness analysis to compare 4 strategies: the old system ("pre-OPTN"), the new Organ Procurement Transplant Network (OPTN) system since August 10, 2017 ("OPTN"), and 2 strategies which restrict simultaneous liver-kidney transplants ("safety net" and "stringent"). We measured "cost" by deployment of deceased donor kidneys (DDKs) to liver transplant recipients and effectiveness by life years (LYs) and quality-adjusted life years (QALYs) in liver transplant recipients. We validated our model against Scientific Registry for Transplant Recipients data.

RESULTS

The OPTN, safety net and stringent strategies were on the efficiency frontier. By rank order, OPTN > safety net > stringent strategy in terms of LY, QALY, and DDK deployment. The pre-OPTN system was dominated, or outperformed, by all alternative strategies. The incremental LY per DDK between the strategies ranged from 1.30 to 1.85. The incremental QALY per DDK ranged from 1.11 to 2.03.

CONCLUSIONS

These estimates quantify the "organ"-effectiveness of various kidney allocation strategies for liver transplant candidates. The OPTN system will likely deliver better liver transplant outcomes at the expense of more frequent deployment of DDKs to liver transplant recipients.

Chronic kidney disease in liver transplantation: Evaluation of kidney function

Chronic kidney disease is one of the main comorbidities affecting liver transplant recipients. Most of those patients have some degree of acute or chronic kidney dysfunction at the time of transplantation, moreover they can also develop de novo chronic kidney disease once transplanted. An important increase in the incidence of chronic kidney disease in the «MELD era» has been observed. This phenomenon has partially been attributed to the weight that kidney function carries for organ allocation. In addition, the generalized use of calcineurin inhibitors has also been a contributing factor. It is of the utmost importance for us to be familiar with the current methods for evaluating kidney function before and after a liver transplantation. The two main biomarkers available today for that purpose are serum creatinine and cystatin C. Several equations have been derived from those biomarkers and have been tested in that context with mixed results, due to their biologic variability and the lack of standardization in their measurement. The gold standard continues to be the direct determination of the glomerular filtration rate through different methods; however, that is only done for research purposes. It is also essential to know the current classification of acute kidney injury and chronic kidney disease in order to make early diagnosis. The present review focuses on the recognition, diagnosis, and classification of chronic kidney disease and acute kidney injury in liver transplantation recipients.

Pretransplantation Cystatin C, but not Creatinine, Predicts 30-day Cardiovascular Events and Mortality in Liver Transplant Recipients With Normal Serum Creatinine Levels

BACKGROUND

The connection between renal dysfunction and cardiovascular dysfunction has been consistently shown. In patients with liver cirrhosis, renal dysfunction shows a tight correlation with prognosis after liver transplantation (LT); therefore, precise renal assessment is mandatory. Cystatin C, a sensitive biomarker for assessing renal function, has shown superiority in detecting mild renal dysfunction compared to classical biomarker creatinine. In this study, we aimed to compare cystatin C and creatinine in predicting 30-day major cardiovascular events (MACE) and all-cause mortality in LT recipients with normal serum creatinine levels.

PATIENTS AND METHODS

Between May 2010 and October 2015, 1181 LT recipients (mean Model for End-stage Liver Disease score 12.1) with pretransplantation creatinine level ≤1.4 mg/dL were divided into tertiles according to each renal biomarker. The 30-day MACE was a composite of troponin I >0.2 ng/mL, arrhythmia, congestive heart failure, death, and cerebrovascular events.

RESULTS

The highest tertile of cystatin C (≥0.95 mg/L) was associated with a higher risk for a 30-day MACE event (odds ratio: 1.62; 95% confidence interval: 1.07 to 2.48) and higher risk of death (hazard ratio: 1.96; 95% confidence interval: 1.04 to 3.67) than the lowest tertile (<0.74 mg/L) after multivariate adjustments. However, the highest tertile of creatinine level showed neither increasing MACE event rate nor worse survival rate compared with the lowest tertile (both insignificant after multivariate adjustment).

CONCLUSIONS

Pretransplantation cystatin C is superior in risk prediction of MACE and all-cause mortality in LT recipients with normal creatinine, compared to creatinine. It would assist further risk stratification which may not be detected with creatinine.

Key roles of hepatologists in successful liver transplantation

Liver transplantation (LT) has been carried out for acute liver failure, end-stage liver disease, and congenital metabolic disease in more than 7000 cases in Japan. Liver transplantation has been established as a treatment option, and survival rates have improved. In 2016, a new registration/allocation policy and a new scoring system for deceased donor LT were established. The management of perioperative patients and preoperative therapy for liver failure, nutrition, and preventing infection were upgraded. Moreover, methods for preventing disease recurrence, and treating hepatitis C and B have been developed and are particularly crucial for good outcomes in LT. Treatment of the complications of obesity, lifestyle-related diseases, and malignancy is also required post-LT. Managing patients after LT contributes to better survival and quality of life. The role of hepatologists is becoming broader and more important.

Renal Impairment in Chronic Hepatitis B: A Review

The liver plays a key role in the metabolism of proteins. Liver dysfunction affects many organs because it communicates with the spleen and all digestive organs through the portal vein. Additionally, the kidney is an organ that is closely related to the liver and is involved in liver diseases. Glomerulonephritis is an important extrahepatic manifestation of chronic hepatitis B virus (HBV) infection. Nucleos(t)ide analog (NA) therapy effectively suppresses HBV replication by inhibiting HBV polymerase, thus decreasing the levels of serum HBV-DNA and delaying the progression of cirrhosis. Although NA therapy is recommended for all patients with chronic HBV infection, regardless of the level of renal dysfunction, there is limited information on NA use in patients with chronic kidney disease. In addition, in patients with end-stage liver cirrhosis, hepatorenal syndrome can be fatal. Hence, we should take into account the stage of impaired renal function in patients with cirrhosis. The aims of this article are to review the epidemiology, clinical presentation, treatment, and prevention of HBV-associated nephropathy.

Serum cystatin C level: An excellent predictor of mortality in patients with cirrhotic ascites

BACKGROUND AND AIM

Although serum cystatin C level is considered a more accurate marker of renal function in patients with liver cirrhosis, its prognostic efficacy remains uncertain. This study aimed to evaluate the prognostic efficacy of serum cystatin C level in patients with cirrhotic ascites.

METHODS

Patients with cirrhotic ascites from 15 hospitals were prospectively enrolled between September 2009 and March 2013. Cox regression analyses were performed to identify independent predictive factors of mortality and development of type 1 hepatorenal syndrome (HRS-1).

RESULTS

In total, 350 patients were enrolled in this study. The mean age was 55.4 ± 10.8 years, and 267 patients (76.3%) were men. The leading cause of liver cirrhosis was alcoholic liver disease (64.3%), followed by chronic viral hepatitis (29.7%). Serum creatinine and cystatin C levels were 0.9 ± 0.4 mg/dL and 1.1 ± 0.5 mg/L, respectively. Multivariate analyses revealed that international normalized ratio and serum bilirubin, sodium, and cystatin C levels were independent predictors of mortality and international normalized ratio and serum sodium and cystatin C levels were independent predictors of the development of HRS-1. Serum creatinine level was not significantly associated with mortality and development of HRS-1 on multivariate analysis.

CONCLUSION

Serum cystatin C level was an independent predictor of mortality and development of HRS-1 in patients with cirrhotic ascites, while serum creatinine level was not. Predictive models based on serum cystatin C level instead of serum creatinine level would be more helpful in the assessment of the condition and prognosis of patients with cirrhotic ascites.

Cystatin C predicts acute kidney injury and mortality in cirrhotics: A prospective cohort study

BACKGROUND & AIMS

Acute kidney injury is a frequent and ominous complication in cirrhosis. An episode of AKI damages the functional nephron mass, compromising the renal functional reserve. We aimed to study the incidence of AKI, probability of subsequent episodes, whether AKI itself predisposes to future AKI and the reliability of serum cystatin C(sCyC) as a biomarker in a prospective cohort of cirrhotics.

PATIENTS AND METHODS

Five hundred and thirty-one cirrhotics without ongoing AKI were followed for development/resolution of AKI. Predictive models for AKI and mortality were developed and validated (Gr. A, Derivative cohort [n = 273], Gr. B, Validation Cohort [n = 258]).

RESULTS

365 episodes of AKI occurred in 233 patients; yielding a mean of 1.56 episodes of AKI per patient. In Gr. A and B, 97 (35.5%) and 78 (30%) patients had prior AKI episodes and were predisposed to further attacks (Gr. A, HR 3.9, 95% CI 2.7-5.6, Gr. B, HR 3.6, 95% CI 2.5-5.4). AKI was thus an independent predictor of the development of new AKI(P < .05) and this risk increased significantly with increase in the number of AKI episodes (P < .001). S.CysC but not s.Cr was an independent predictor of new AKI on multivariate analysis. "AKI-Score" incorporating CysC; and the addition of Cyst into components of MELD, that is the "MELD-Cystatin" score predicted the development of AKI and mortality, respectively, and performed significantly better than the MELD and CTP scores.

CONCLUSIONS

An episode of AKI itself predisposes to subsequent attacks of AKI in cirrhotics. Scores incorporating CysC can accurately predict the development of AKI and mortality in these patients.