Baseline serum cystatin C as a marker of acute kidney injury in patients with acute-on-chronic liver failure

Neutrophil gelatinase-associated lipocalin for predicting acute kidney injury in orthotopic liver transplantation: a systematic review and meta-analysis

Acute kidney injury (AKI) is associated with poor prognosis. New biomarkers, like neutrophil gelatinase-associated lipocalin (NGAL), are helpful for early warning of AKI. This study aims to investigate the accuracy of NGAL in evaluating the perioperative AKI of liver transplantation. The four databases, PubMed, Web of Science, Embase, and Cochrane Library, were searched for relevant studies published from database inception to August 2023. Results were pooled using random-effects models, and heterogeneity was examined. A total of 16 case-control studies with 1271 patients were included. The results showed that both preoperative [standardized mean difference (SMD) = 0.53; 95% confidence interval (CI): 0.15, 0.91; P  < 0.001] and postoperative NGAL levels (SMD = 0.63; 95% CI: 0.24, 1.03; P  < 0.001) were higher in the AKI group compared with the non-AKI group. Subgroup analysis by continents showed higher preoperative NGAL levels in AKI patients in the European population (SMD = 1.63; 95% CI: 0.55, 0.27; P  = 0.003), but no differences in Asian, African, North American, and South American. Subgroup analysis by continents revealed higher postoperative NGAL levels in the European (SMD = 1.63; 95% CI: 0.55, 0.27; P  = 0.002) and Asian populations (SMD = 0.42; 95% CI: 0.04, 0.81; P  = 0.039). Higher postoperative NGAL levels in plasma and urine were observed in AKI patients compared with non-AKI patients [plasma (SMD = 1.29; 95% CI: 0.21, 2.38; P  = 0.011), urine (SMD = 0.88; 95% CI: 0.18, 1.59; P  = 0.035)], while there was no difference in African, North American, South American, and serum NGAL. NGAL level may be an important biomarker for early detection of AKI in the perioperative period of liver transplantation.

Understanding acute kidney injury in cirrhosis: Current perspective

Acute kidney injury (AKI) is present in 30%-40% of hospitalized patients with cirrhosis. Its incidence is higher in patients with severe alcoholic hepatitis, spontaneous bacterial peritonitis, and acute-on-chronic-liver failure (ACLF). Kidney injury is an important landmark event in the natural history of cirrhosis as it is associated with higher mortality. Overwhelming systemic vasodilation, cardiac dysfunction, hypoperfusion, endotoxemia, and direct nephrotoxicity predispose patients with cirrhosis to kidney injury. Infection is present in 25% of patients with decompensated cirrhosis and 35%-40% of patients with ACLF. Advanced cirrhosis with portal hypertension leads to a sluggish portal flow, leading to increased gut congestion, altered gut permeability and bacterial translocations. They drive infection and endotoxemia in such patients. Pathogen-associated molecular patterns activate inflammatory cascades, which leads to further deterioration in hemodynamics and reduced glomerular filtration rate. Infections and pro-inflammatory cytokines like interleukin 6 (IL-6), IL-1, and tumor necrosis factor alpha may directly cause kidney parenchymal injury. The combined effect of dysfunctional albumin and systemic and splanchnic vasodilatation leads to low effective blood volume, activating the renin-angiotensin-aldosterone system. This causes renal vasoconstriction, water retention, and ascites, which progresses to hepatorenal physiology and AKI development. Vasoconstriction and volume expansion effectively improve arterial blood volume and systemic hemodynamics, thereby improving renal blood flow. It is of paramount importance to predict, detect, and treat AKI in its early state, as progressive renal dysfunction is invariably associated with higher mortality in patients with decompensated cirrhosis and ACLF. This comprehensive review will focus on the recent evolving concepts of the pathophysiology, diagnosis, and management of AKI in patients with cirrhosis.

Evaluation of Acute Kidney Injury (AKI) Biomarkers FABP1, NGAL, Cystatin C and IL-18 in an Indian Cohort of Hospitalized Acute-on-chronic Liver Failure (ACLF) Patients

Background/Aims

Acute-on-chronic liver failure (ACLF) is a complication of cirrhosis associated with systemic inflammation and organ dysfunction. In ACLF, the development of acute kidney injury (AKI) is associated with poor outcomes. FABP1, NGAL, Cys C and IL-18 have been shown to correlate with ACLF severity and mortality. Hence, our study aimed to evaluate the association of these biomarkers with organ dysfunctions, particularly AKI, in an Indian ACLF patient cohort.

Methods

151 study participants including ACLF (n = 91; with AKI n = 63, no-AKI n = 28), non-liver AKI (n = 30) and healthy controls (n = 30) were recruited. Serum ELISA was performed for biomarker estimation. Data interpolation and graphical representation were performed using GraphPad Prism and statistical analyses performed using STATA 14.0.

Results

FABP1 and Cys C levels were higher in ACLF-AKI patients compared to ACLF no-AKI (P-value ≤ 0.0005). Serum Cys C levels were significantly increased in non-liver AKI compared to ACLF-AKI (P-value ≤ 0.001). AUROC analysis showed better performance of Cys C (AUC 0.79; 95% CI (0.68-0.89)) compared to serum creatinine (AUC 0.71; 95% CI (0.61-0.82)) in discriminating AKI and no-AKI. Correlation analysis revealed positive correlations of FABP1 with creatinine and urea, Cys C with creatinine, urea and OF-Kidney, NGAL, and IL-18 with general markers of organ dysfunction. Plasma MTs) measured in a subset of ACLF patients were elevated in progression-to-AKI.

Conclusion

Our study showed that in an Indian population of ACLF patients with a high short-term mortality, serum Cys C and FABP1 were elevated in ACLF-AKI, however did not have predictive potential for ACLF-AKI. Cys C levels were significantly higher in non-liver AKI patients vs. ACLF-AKI and correlated with markers of kidney dysfunction whereas NGAL and IL-18 represented higher inflammation and total organ dysfunction. Hence, we conclude that these biomarkers were elevated in ACLF-AKI but did not have predictive potential for AKI in ACLF.

Can Novel Biomarkers Effectively Predict Acute Kidney Injury in Liver or Kidney Transplant Recipients?

Acute kidney injury (AKI) constitutes a common complication associated with liver or kidney transplantation, which may significantly impact the graft condition and perioperative mortality. Current AKI diagnostic criteria based on serum creatinine (sCr) and urine output alterations are widely utilized in routine clinical practice. However, the diagnostic value of sCr may be limited by various confounding factors, including age, sex, reduced or increased muscle mass, and pre-existing chronic kidney disease (CKD). Furthermore, sCr is rather a late indicator of AKI, as its concentration tends to increase only when the severity of the injury is enough to decrease the estimated glomerular filtration rate (eGFR). Recent expertise highlights the need for novel biomarkers in post-transplantation AKI diagnosis, prediction of event-associated mortality, or evaluation of indications for renal replacement treatment (RRT). Over the last decade, the diagnostic performance of various AKI biomarkers has been assessed, among which some showed the potential to outperform sCr in AKI diagnosis. Identifying susceptible individuals, early diagnosis, and prompt intervention are crucial for successful transplantation, undisturbed graft function in long-term follow-up, and decreased mortality. However, the research on AKI biomarkers in transplantation still needs to be explored. The field lacks consistent results, rigorous study designs, and external validation. Considering the rapidly growing prevalence of CKD and cirrhosis that are associated with the transplantation at their end-stage, as well as the existing knowledge gap, the aim of this article was to provide the most up-to-date review of the studies on novel biomarkers in the diagnosis of post-transplantation AKI.

Definitions, Etiologies, and Outcomes of Acute on Chronic Liver Failure: A Systematic Review and Meta-analysis

BACKGROUND & AIMS

Acute-on-chronic liver failure (ACLF) is a major public health concern. We aimed to assess the definitions, etiologic spectrum, organ failure (OF), and outcomes of ACLF globally.

METHODS

Three databases were searched for studies on ACLF from 1990 until September 2022. Information regarding definitions, acute precipitants, underlying chronic liver disease (CLD), OF, and mortality were extracted. Meta-analyses were performed for pooled prevalence rates (95% confidence interval [CI]) using random-effects model for each definition of ACLF.

RESULTS

Of the 11,451 studies identified, 114 articles (142 cohorts encompassing 210,239 patients) met the eligibility criteria. Most studies (53.2%) used the European Association for the Study of the Liver (EASL) definition, followed by Asia-Pacific Association for the Study of the Liver (APASL) (33.3%). Systemic infection was the major acute precipitant, and alcohol use was the major cause of CLD in EASL-defined studies, whereas alcohol was both the major acute precipitant and cause of CLD in APASL-defined studies. Liver failure was the major OF in APASL-based studies, whereas renal failure was predominant in EASL-based studies. Thirty-day mortality varied across definitions: APASL: 38.9%, 95% CI, 31.2%-46.9%; EASL: 47.9%, 95% CI, 42.2%-53.5%; and NACSELD: 52.2%, 95% CI, 51.9%-52.5%. Diagnostic overlap between definitions ranged from 7.7% to 80.2%. Meta-regression suggested that the World Health Organization region influenced 30-day mortality in studies using EASL definition.

CONCLUSIONS

Heterogeneity in the definition of ACLF proposed by different expert societies and regional preferences in its use result in differences in clinical phenotype and outcomes. A uniform definition would enhance the comparability and interpretation of global data.

APASL clinical practice guidelines on the management of acute kidney injury in acute-on-chronic liver failure

Acute-on-chronic liver failure (ACLF) is a syndrome that is characterized by the rapid development of organ failures predisposing these patients to a high risk of short-term early death. The main causes of organ failure in these patients are bacterial infections and systemic inflammation, both of which can be severe. For the majority of these patients, a prompt liver transplant is still the only effective course of treatment. Kidneys are one of the most frequent extrahepatic organs that are affected in patients with ACLF, since acute kidney injury (AKI) is reported in 22.8-34% of patients with ACLF. Approach and management of kidney injury could improve overall outcomes in these patients. Importantly, patients with ACLF more frequently have stage 3 AKI with a low rate of response to the current treatment modalities. The objective of the present position paper is to critically review and analyze the published data on AKI in ACLF, evolve a consensus, and provide recommendations for early diagnosis, pathophysiology, prevention, and management of AKI in patients with ACLF. In the absence of direct evidence, we propose expert opinions for guidance in managing AKI in this very challenging group of patients and focus on areas of future research. This consensus will be of major importance to all hepatologists, liver transplant surgeons, and intensivists across the globe.

Association of serum creatinine to cystatin C to waist circumference ratios and hypertension: evidence from China health and retirement longitudinal study

Background

The objective of this study was to explore the association between the ratio of serum creatinine to cystatin C to waist circumference (CCR/WC) and hypertension.

Methods

The study utilized data extracted from the China Health and Retirement Longitudinal Study. In the cross-sectional analysis, logistic regression analyses were employed to examine the association between the CCR/WC ratio and hypertension. By utilizing restricted cubic splines, potential non-linear associations between the CCR/WC ratio and hypertension were explored. In the longitudinal analysis, the association between CCR/WC quartiles (Q1-Q4) and the risk of new-onset hypertension was evaluated by Cox proportional-hazards models.

Results

In total, 7,253 participants were enrolled. The study unveiled an inverse association with hypertension, demonstrating an odds ratio (OR) of 0.29 (95% confidence interval [CI]: 0.23-0.37, P < 0.001). Among males, an OR of 0.38 (95% CI: 0.25-0.58, P < 0.001) was observed, while among females, an OR of 0.41 (95% CI: 0.28-0.60, P < 0.001) was noted. There was an absence of a nonlinear association between the CCR/WC ratio and hypertension. Cox regression analysis unveiled a reduced risk of hypertension in Q3 (Hazard ratios [HR]: 0.69, 95% CI: 0.58-0.82, P < 0.001) and Q4: (HR: 0.70, 95% CI: 0.59-0.83, P < 0.001) in compared to the Q1 of the CCR/WC ratio, and sex-specific analysis yielded consistent results.

Conclusion

This study emphasizes the potential association between an elevated CCR/WC ratio and a reduced risk of hypertension.

Determination of HMGB1 in hepatitis B virus-related acute-on-chronic liver failure patients with acute kidney injury: Early prediction and prognostic implications

Background: Acute kidney injury (AKI) is a frequent complication in patients with hepatitis B virus-related acute-on-chronic liver failure (HBV-ACLF) and is associated with high rates of mortality. We aimed to estimate serum high mobility group protein 1 (HMGB1) levels in hepatitis B virus-related acute-on-chronic liver failure patients and analyze their clinical value in the development and outcomes of Acute kidney injury. Methods: A total of 251 consecutive patients with hepatitis B virus-related acute-on-chronic liver failure were enrolled in this retrospective study. Using the International Club of Ascites staging criteria of Acute kidney injury, 153 patients developed Acute kidney injury. The clinical data of patients were collected and serum levels of high mobility group protein 1 were measured by ELISA. All patients were followed up until death or for a minimum of 3 months. Early prediction and prognostic implications of high mobility group protein 1 in Hepatitis B Virus-Related Acute-on-Chronic Liver Failure Patients with Acute Kidney Injury were investigated in different cohorts, including a propensity score-matched ACLF cohort. Results: Among all individuals with hepatitis B virus-related acute-on-chronic liver failure, the incidence of Acute kidney injury was 61.0% (153/251). The patients who developed stage 2/3 Acute kidney injury showed the highest high mobility group protein 1 levels, followed by those who developed stage 1 Acute kidney injury, and those without Acute kidney injury showed the lowest high mobility group protein 1 levels. Moreover, high mobility group protein 1 levels were significantly higher in non-survivors than in survivors among hepatitis B virus-related acute-on-chronic liver failure patients with Acute kidney injury. Furthermore, analysis of the area under the receiver operating characteristic curve (AUROC) indicated that serum high mobility group protein 1 levels (pre-matching: AUC = 0.740; post-matching: AUC = 0.661) may be a potential predictive factor for Acute kidney injury development and that high mobility group protein 1 (AUC = 0.727) might be a reliable biomarker for prognosis in patients with Acute kidney injury. Conclusion: In patients with hepatitis B virus-related acute-on-chronic liver failure, Acute kidney injury is universal. Acute kidney injury and its stages negatively influence the 90-day transplant-free mortality rate. Serum high mobility group protein 1 levels can serve as a positive predictor of Acute kidney injury development, and high mobility group protein 1 might also be a prognostic biomarker for Acute kidney injury among hepatitis B virus-related acute-on-chronic liver failure patients.

Novel biomarkers of acute kidney injury in chronic liver disease: Where do we stand after a decade of research?

Acute kidney injury (AKI) is a frequently encountered complication in decompensated chronic liver disease (CLD) with an estimated prevalence of 20%-50% among hospitalized patients. AKI often heralds the onset of a downhill course in the natural history of CLD. Serum creatinine has several limitations as a stand-alone marker of AKI in patients with decompensated CLD. The concept of hepatorenal syndrome, the prototype of AKI in decompensated CLD, has evolved tremendously over recent years. There is emerging evidence of an additional "structural" component in the pathophysiology of hepatorenal syndrome-AKI, which was previously identified as a purely "functional" form of renal impairment. Lacunae in the existent biochemical arsenal for diagnosis and prognosis of AKI have fueled enthusiastic research in the field of novel biomarkers of kidney injury in patients with cirrhosis. The advent of these biomarkers provides a crucial window of opportunity to improve the diagnosis and clinical outcomes of this vulnerable cohort of patients. This review summarizes the dynamic concept of renal dysfunction in CLD and the available literature on the role of novel biomarkers of AKI in assessing renal function, identifying AKI subtypes, and predicting prognosis. There is special emphasis on the renal tubular injury marker, neutrophil gelatinase-associated lipocalin, the most exhaustively studied biomarker of AKI in the CLD population.