Relations of liver fat with prevalent and incident chronic kidney disease in the Framingham Heart Study: A secondary analysis

Longitudinal Outcomes Associated With Metabolic Dysfunction-Associated Steatotic Liver Disease: A Meta-analysis of 129 Studies

BACKGROUND & AIMS

The progression of metabolic dysfunction-associated steatotic liver disease (MASLD) has been found to manifest in a series of hepatic and extrahepatic complications. A comprehensive meta-analysis of the longitudinal outcomes associated with MASLD has yet to be conducted.

METHODS

To investigate the longitudinal outcomes associated with MASLD, Medline and Embase databases were searched to identify original studies that evaluated the longitudinal risks of incident clinical outcomes among MASLD patients compared with non-MASLD individuals. DerSimonian Laird random-effects meta-analysis was performed. Pooled effect estimates were calculated, and heterogeneity among studies was evaluated.

RESULTS

One hundred twenty-nine studies were included in the meta-analysis. Meta-analysis revealed a significant increase in the risk of cardiovascular outcomes (hazard ratio [HR], 1.43; 95% confidence interval [CI], 1.27-1.60; P < .01), various metabolic outcomes such as incident hypertension (HR, 1.75; 95% CI, 1.46-2.08; P < .01), diabetes (HR, 2.56; 95% CI, 2.10-3.13; P < .01), pre-diabetes (HR, 1.69; 95% CI, 1.22-2.35; P < .01), metabolic syndrome (HR, 2.57; 95% CI, 1.13-5.85; P = .02), chronic kidney disease (HR, 1.38; 95% CI, 1.27-1.50; P < .01), as well as all cancers (HR, 1.54; 95% CI, 1.35-1.76; P < .01) among MASLD patients compared with non-MASLD individuals. By subgroup analysis, MASLD patients with advanced liver disease (HR, 3.60; 95% CI, 2.10-6.18; P < .01) were also found to be associated with a significantly greater risk (P = .02) of incident diabetes than those with less severe MASLD (HR, 1.63; 95% CI, 1.0-2.45; P = .02) when compared with non-MASLD.

CONCLUSIONS

The present study emphasizes the association between MASLD and its clinical outcomes including cardiovascular, metabolic, oncologic, and other outcomes. The multisystemic nature of MASLD found in this analysis requires treatment targets to reduce systemic events and end organ complications.

Shifting perspectives in liver diseases after kidney transplantation

Liver diseases after kidney transplantation range from mild biochemical abnormalities to severe hepatitis or cirrhosis. The causes are diverse and mainly associated with hepatotropic viruses, drug toxicity and metabolic disorders. Over the past decade, the aetiology of liver disease in kidney recipients has changed significantly. These relates to the use of direct-acting antiviral agents against hepatitis C virus, the increasing availability of vaccination against hepatitis B and a better understanding of drug-induced hepatotoxicity. In addition, the emergence of the severe acute respiratory syndrome coronavirus 2 pandemic has brought new challenges to kidney recipients. This review aims to provide healthcare professionals with a comprehensive understanding of recent advances in the management of liver complications in kidney recipients and to enable them to make informed decisions regarding the risks and impact of liver disease in this population.

The liver-kidney axis: Is serum leptin a potential link in non-alcoholic fatty liver disease-associated chronic kidney disease?

BACKGROUND AND STUDY AIMS

Non-alcoholic fatty liver disease (NAFLD) is an independent risk factor for chronic kidney disease (CKD). Previous studies argued that leptin levels increase significantly with the progression of CKD. But the association between leptin and CKD has not been investigated in patients with NAFLD. Therefore, we conducted this study to establish whether increased leptin level is associated with CKD in NAFLD patients.

PATIENTS AND METHODS

In our prospective study with a follow up period of six months thirty-five teetotaller biopsy-proven NAFLD patients were divided as groups with mild, versus advanced, fibrosis. Liver fibrosis was also assessed with Fibroscan. Serum leptin levels were measured by radioimmunoassay. For insulin resistance we used the homeostasis model assessment method (HOMA-IR). For the kidney function, we used the abbreviated formula Modification of Diet in Renal Disease (MDRD) formula, which estimates GFR. For statistical analysis, Student's-t test, Mann-Whitney test, linear regression-binary logistic regression analyses and the ROC curve analysis were used.

RESULTS

Advanced fibrosis and increased HOMA-IR were risk factors for decreased eGFR. Leptin correlated inversely with advanced fibrosis (p: 0.03) and low leptin was a risk factor for CKD (p: 0.02). In ROC curve analysis, advanced fibrosis and low leptin were risk factors for decreased eGFR (p: 0.007 and 0.004, respectively). Low leptin level was dependently associated with decreased eGFR.

CONCLUSION

Advanced fibrosis in NAFLD patients is a risk factor for CKD. Leptin correlated inversely with advanced fibrosis. Unlike the previous studies, which were not performed in NAFLD patients, we found decreased leptin in NAFLD patients with decreased eGFR. Low leptin level was found to be a dependent predictor for differentiating NAFLD patients with high risk for CKD.

Association between the fatty liver index and chronic kidney disease: the population-based KORA study

BACKGROUND

We aimed to evaluate the relationship of fatty liver, estimated by fatty liver index (FLI), with kidney function and chronic kidney disease (CKD) in a German cohort study, given the lack of prospective evidence in Europeans.

METHODS

We included 2920 participants (51.6% women, mean age 56.1 years) from the KORA study, of which 1991 were followed up for an average of 6.4 (± 0.3) years. Kidney function was assessed using the glomerular filtration rate estimated by creatinine (eGFR-cr) or cystatin C (eGFR-cc). We used multiple logistic or linear regressions to evaluate the associations between FLI, kidney function and CKD (eGFR < 60 ml/min per 1.73 m2), and mediation analysis to explore the mediation effects of metabolic factors.

RESULTS

The prevalence of FLI ≥ 60 and CKD were 40.4% and 5.6% at baseline, and 182 participants developed CKD during the follow-up. Cross-sectionally, FLI was significantly inversely associated with eGFR-cc [β, 95%CI: -1.14 (-1.81, -0.47)] and prevalent CKD based on eGFR-cc [OR, 95%CI: 1.28 (1.01, 1.61)], but not with other markers. After adjusting for lifestyle factors, we found a positive association between FLI and incident CKD defined by eGFR-cc or/eGFR-cr, which was attenuated after controlling for metabolic risk factors. Mediation analysis showed that the association was completely mediated by inflammation, diabetes and hypertension jointly.

CONCLUSIONS

The positive association between FLI and CKD incidence was fully mediated by the joint effect of metabolic risk factors. Future longitudinal studies need to explore the chronological interplay between fatty liver, cardiometabolic risk factors and kidney function with repeated measurements.

Influence of Nonalcoholic Fatty Liver Disease on the Occurrence and Severity of Chronic Kidney Disease

Nonalcoholic fatty liver disease (NAFLD) is reported to affect 20-30% of adults and is accompanied by various metabolic comorbidities, where the economic and clinical burden of NAFLD is attributed to the progression of liver disease as well as the presence of extrahepatic diseases. Chronic kidney disease (CKD), which has a high incidence rate, high morbidity and mortality rates, and high medical costs, has been linked to NAFLD. CKD is associated with some metabolism-related risk factors that overlap with metabolic comorbidities of NAFLD. Therefore, to investigate the potential factors that influence CKD occurrence, the association between NAFLD and CKD should be clarified. Some studies have confirmed that NAFLD influences the occurrence and severity of CKD, whereas some studies have indicated that there is no correlation. In this review, the results of a few studies have been discussed, the potential risk factors for CKD in NAFLD are explored, and the respective biological mechanisms are elaborated to help clinicians identify CKD in patients much earlier than it is diagnosed now and thus help in reducing the incidence of liver and kidney transplants.

A clinical overview of non-alcoholic fatty liver disease: A guide to diagnosis, the clinical features, and complications-What the non-specialist needs to know

Non-alcoholic fatty liver disease (NAFLD) has a rapidly rising prevalence worldwide and is the most common cause of liver disease in developed countries. In this article, we discuss the spectrum of disease of NAFLD with a focus on the earlier spectrum of the disease that is commonly encountered by non-specialists, as well as the hepatic and extra-hepatic associations of the disease. We discuss in detail the two common presentations of NAFLD, incidentally detected hepatic steatosis and asymptomatic raised liver enzymes, and provide an algorithm for management and continued to follow up for these patients. Considerations for the management of cardiovascular comorbidities in these patients are also discussed. Finally, we cover the topic of screening for NAFLD in high-risk populations.

Non-alcoholic fatty liver disease and risk of incident chronic kidney disease: an updated meta-analysis

OBJECTIVE

Studies reported a significant association between non-alcoholic fatty liver disease (NAFLD) and increased risk of chronic kidney disease (CKD). However, whether this risk changes with increasing severity of NAFLD remains uncertain. We performed a meta-analysis of observational studies to quantify the magnitude of the association between NAFLD and risk of incident CKD.

DESIGN

We systematically searched PubMed, Web of Science and Scopus from January 2000 to August 2020 using predefined keywords to identify observational studies with a follow-up duration of ≥1 year, in which NAFLD was diagnosed by blood biomarkers/scores, International Classification of Diseases codes, imaging techniques or biopsy. Data from selected studies were extracted, and meta-analysis was performed using random-effects modelling.

RESULTS

13 studies with 1 222 032 individuals (28.1% with NAFLD) and 33 840 cases of incident CKD stage ≥3 (defined as estimated glomerular filtration rate <60 mL/min/1.73 m², with or without accompanying overt proteinuria) over a median follow-up of 9.7 years were included. NAFLD was associated with a moderately increased risk of incident CKD (n=10 studies; random-effects HR 1.43, 95% CI 1.33 to 1.54; I² =60.7%). All risks were independent of age, sex, obesity, hypertension, diabetes and other conventional CKD risk factors. Sensitivity analyses did not alter these findings. Funnel plot did not reveal any significant publication bias.

CONCLUSION

This large and updated meta-analysis indicates that NAFLD is significantly associated with a~1.45-fold increased long-term risk of incident CKD stage ≥3. Further studies are needed to examine the association between the severity of NAFLD and risk of incident CKD.

NAFLD and renal function in children: is there a genetic link?

Introduction: Over the past decades, a large amount of both adult and pediatric data has shown relationship between Nonalcoholic Fatty Liver Disease (NAFLD) and chronic kidney disease (CKD), resulting in an overall increased cardiometabolic burden. In view of the remarkable role of the genetic background in the NAFLD pathophysiology, a potential influence of the major NAFLD polymorphisms (e.g. the I148M variant of the Patatin-like phospholipase containing domain 3 (PNPLA3) gene, the E167K allele of the Transmembrane 6 superfamily member 2 (TM6SF2), the hydroxysteroid 17-beta dehydrogenase 13 (HSD17B13), and the Membrane bound O-acyltransferase domain containing 7-transmembrane channel-like 4 (MBOAT7-TMC4) genes) on renal function has been supposed. A shared metabolic and proinflammatory pathogenesis has been hypothesized, but the exact mechanism is still unknown.Areas covered: We provide a comprehensive review of the potential genetic link between NAFLD and CKD in children. Convincing both adult and pediatric evidence supports this association, but there is some dispute especially in childhood.Expert opinion: Evidence supporting a potential genetic link between NAFLD and CKD represents an intriguing aspect with a major clinical implication because of its putative role in improving strategy programs to counteract the higher cardiometabolic risk of these patients.

Non-alcoholic fatty liver disease is associated with increased risk of chronic kidney disease

Background and Aims

Whether non-alcoholic fatty liver disease (NAFLD) is associated with an increased risk of incident chronic kidney disease (CKD) independent of established cardio-renal risk factors remains controversial. We aimed to provide a quantitative estimate of the association and strength between NAFLD and risk of CKD after adjustment for multiple cardio-renal risk factors.

Methods

We searched electronic databases (PubMed, Embase, and Google Scholar) for studies published from database inception until 30 November 2020. Analysis included cohort studies that reported multivariable-adjusted risk ratios [including odds ratios, relative risks (RRs), or hazard ratios] and 95% confidence intervals (CIs) for CKD of NAFLD compared with individuals without NAFLD.

Results

A total of 11 cohort studies were included comprising 1,198,242 participants (46.3% women) for analysis. The median follow-up duration was 3.7 years, with 31,922 cases of incident CKD. Compared with individuals without NAFLD, unadjusted models showed that NAFLD was associated with a higher risk of CKD (RR 1.54, 95% CI 1.38-1.71). After adjusting for multiple cardio-renal risk factors, the CKD risk was still significantly increased in patients with NAFLD (RR 1.39, 95% CI 1.27-1.52). Compared with individuals without NAFLD, the adjusted absolute risk increase in NAFLD for CKD was 5.1 (95% CI 3.5-6.8) per 1000 person-years.

Conclusion

NAFLD is associated with an increased risk of incident CKD independent of established cardio-renal risk factors.

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.

Importance of non-invasive liver fibrosis scores for mortality and complications development in individuals with type 2 diabetes

AIMS

To evaluate the non-alcoholic fatty liver disease (NAFLD) fibrosis score (NFS) and Fibrosis-4 score (FIB4) as predictors of complications development and mortality in a cohort of type 2 diabetes.

METHODS

554 type 2 diabetic subjects had NFS and FIB4 calculated at baseline. Multivariate Cox and Poisson analyses evaluated the associations between fibrosis scores and the occurrence of microvascular and cardiovascular complications, and all-cause mortality.

RESULTS

According to recommended cut-offs of NFS, 12.8% had advanced fibrosis and 45.9% had absence of advanced fibrosis and of FIB4, 3.8% and 86.1%, respectively. During a median follow-up of 11 years, 217subjects died, 172 had cardiovascular events (CVEs), 184 had renal events, and 139 had retinopathy and 185 neuropathy events. As continuous variables, both scores predicted all-cause mortality: NFS, HR: 1.30 (p = 0.032) and FIB4, HR: 1.24 (p = 0.021); an increased NFS implied in a significant 90% excess risk of mortality, whereas a higher FIB4 in a borderline 69% higher risk. The scores were mainly predictors of mortality in women and for non-cardiovascular deaths. The NFS was a predictor of renal events, mainly for renal function deterioration.

CONCLUSIONS

The NFS and FIB4 predicted all-cause mortality, particularly in women and for non-cardiovascular causes. The NFS predicted adverse renal outcomes. These liver fibrosis scores may improve stratification risk in individuals with diabetes and NAFLD.

Early Kidney Dysfunction in Metabolic-Associated Fatty Liver Disease: Is Transient Elastography Useful as a Screening Method?

INTRODUCTION

Increasing evidence suggests an association between metabolic-associated fatty liver disease (MAFLD) and CKD. Timely prediction of early kidney dysfunction (EKD) is thus essential in this population although a screening method is not stablished. We aimed to evaluate the role of transient elastography (TE) in predicting EKD in patients with MAFLD.

MATERIALS AND METHODS

A prospective cohort study that included patients with MAFLD scheduled for evaluation was performed between May 2019 and January 2020. Demographic, clinical, and laboratory data and TE parameters were prospectively obtained. EKD was defined as microalbuminuria (urinary albumin-to-Cr ratio 30-300 mg/g) and estimated glomerular filtration rate ≥60 mL/min/1.73 m2. Significant liver fibrosis was defined as liver stiffness measurement (LSM) ≥8.2 kPa.

RESULTS

Of the included 45 patients with MALFD, 53.3% were of female gender with mean age of 53.5 ± 10.9 years. EKD was found in 17.8% of patients. MAFLD patients with EKD were significantly more obese (BMI ≥30) (75.0 vs. 32.4%, p = 0.045) and had significantly higher LSM (8.5 ± 4.1 vs. 5.8 ± 2.2 kPa, p = 0.01). After adjustment of potential confounders for EKD, the presence of liver fibrosis remained a significant predictor of EKD, being associated with a 14.3-fold increased risk of EKD (p = 0.04). The optimal cutoff value of LSM to predict EKD was 6.1 kPa (sensitivity: 85.7%; specificity: 67.6%).

CONCLUSION

Significant liver fibrosis is associated with a significant increased risk of EKD in patients with MAFLD, regardless of other comorbidities. Higher levels of LSM, particularly >6.1 kPa, alert for timely identification of EKD and associated comorbidities, as well as their control, in order to prevent the development of CKD in the long term.

Association between NAFLD and risk of prevalent chronic kidney disease: why there is a difference between east and west?

Backgrounds

There is a discrepancy between west and east on the relationship between non-alcoholic fatty liver disease (NAFLD) and chronic kidney disease (CKD). This study aimed to find out the possible reason for this and to clarify the association between NAFLD and CKD by analyzing two population-based datasets from the US and China.

Methods

Two health examination datasets from China and the US were used. CKD was defined as an estimated glomerular filtration rate (eGFR) < 60 ml/min/1.73m² or and/or abnormal albuminuria and/or overt proteinuria. Binary logistic regression was used to examine the association between NAFLD and CKD.

Results

A total of 60,965 participants were analyzed, including 11,844 from the US and 51,229 from China. The prevalence of NAFLD was 27.12% in the Chinese population and 36.08% in the US population (p < 0.001). The proportions of CKD and late stage CKD (stages 3–5) were higher in the US population than the Chinese one. NAFLD was independently associated with an increased risk of CKD in Chinese population, whereas in the US population, the NAFLD was not an independent risk factor of CKD. In subgroup analyses which excluded late stages CKD (stages 3–5), the risks of mild renal function decline became consistent: NAFLD was associated with early stages of CKD but not the late stages of CKD in both populations.

Conclusion

NAFLD increased the risk of early stages of CKD in both Chinese and the US population. The conflicting results reported by previous studies might result from the different proportion of late stages of CKD.

Risk of Kidney Dysfunction IN Nafld

Background:

The timely identification of traditional and non-traditional precursors and risk factors for chronic kidney disease (CKD) (a common systemic disease defined as a decreased kidney function documented by reduced glomerular filtration rate, or markers of kidney damage, or both) is relevant in clinical practice, as CKD increases the risk of end-stage renal disease and other serious comorbidities. A possible relationship between non-alcoholic fatty liver disease (NAFLD) (which is to date the most common chronic disease worldwide) and CKD has recently gained significant attention of researchers.

Methods :

A systematic literature search using appropriate keywords was made in order to identify relevant articles that have investigated the association between NAFLD and CKD.

Results:

Several observational studies and meta-analyses have reported the existence of an independent association between NAFLD and risk of CKD in patients with and without diabetes. However, whilst the association between NAFLD and risk of prevalent CKD is strong across various patient populations, whether NAFLD is independently associated with the development and progression of CKD is still debatable. Moreover, emerging evidence now suggests a potential association between patatin-like phospholipase domain-containing protein-3 (PNPLA3) rs738409 genotype (the most important genetic variant associated to NAFLD) and decreasing kidney function, independent of NAFLD.

Conclusions :

Convincing evidence now indicates that CKD is increased among patients with NAFLD. For this reason, patients with NAFLD should be regularly monitored for renal function and, on the other hand , NAFLD should be considered in all patients with CKD, especially if they are obese or have type 2 diabetes.

NAFLD as a driver of chronic kidney disease

Non-alcoholic fatty liver disease (NAFLD) and chronic kidney disease (CKD) are worldwide public health problems, affecting up to 25-30% (NAFLD), and up to 10-15% (CKD) of the general population. Recently, it has also been established that there is a strong association between NAFLD and CKD, regardless of the presence of potential confounding diseases such as obesity, hypertension and type 2 diabetes. Since NAFLD and CKD are both common diseases that often occur alongside other metabolic conditions, such as type 2 diabetes or metabolic syndrome, elucidating the relative impact of NAFLD on the risk of incident CKD presents a substantial challenge for investigators working in this research field. A growing body of epidemiological evidence suggests that NAFLD is an independent risk factor for CKD and recent evidence also suggests that associated factors such as metabolic syndrome, dysbiosis, unhealthy diets, platelet activation and processes associated with ageing could also contribute mechanisms linking NAFLD and CKD. This narrative review provides an overview of the literature on: a) the evidence for an association and causal link between NAFLD and CKD and b) the underlying mechanisms by which NAFLD (and factors strongly linked with NAFLD) may increase the risk of developing CKD.

PNPLA3 gene and kidney disease

Chronic kidney disease (CKD) is a disease regularly seen in clinical practice. At present, CKD is described as a change of kidney structure and/or function and it is classified in relation to cause, values of glomerular filtration rate and albuminuria category. Seeing that CKD is closely linked to the development of end-stage renal disease and other comorbidities, the determination of additional independent predictors for CKD is clinically necessary. At present, there is evidence associating non-alcoholic fatty liver disease (NAFLD) with CKD, thereby suggesting that NAFLD patients may require intensive surveillance to reduce their risk of CKD. In 2008, genome-wide association studies documented an association between the variant rs738409 (C > G p.I148M) in the patatin-like phospholipase domain containing 3 (PNPLA3) gene (mainly implicated in the lipid regulation) and the entire spectrum of NAFLD (i.e., liver steatosis, non-alcoholic steatohepatitis, fibrosis, and hepatocellular carcinoma). In the last years, accumulating epidemiological evidence suggests the existence of a relationship between PNPLA3 rs738409 and risk of CKD, indicating that rs738409 may also contribute to the kidney injury. This is of particular scientific interest, as such association may explain, at least in part, the epidemiological association between liver and kidney disease. In this narrative review, we will discuss the accumulating evidence regarding the association between PNPLA3 rs738409 and risk of CKD, the putative biological mechanisms underpinning such relationship, and the possible future perspective.

Sex specificity of kidney markers to assess prognosis in cirrhotic patients with TIPS

BACKGROUND & AIMS

Renal function assessed by creatinine is a key prognostic factor in cirrhotic patients. However, creatinine is influenced by several factors, rendering interpretation difficult in some situations. This is especially important in early stages of renal dysfunction where renal impairment might not be accompanied by an increase in creatinine. Other parameters, such as cystatin C (CysC) and beta-trace protein (BTP), have been evaluated to fill this gap. However, none of these studies have considered the role of the patient's sex. The present study analysed CysC and BTP to evaluate their prognostic value and differentiate them according to sex.

PATIENTS AND METHODS

CysC and BTP were measured in 173 transjugular intrahepatic portosystemic shunt (TIPS)-patients from the NEPTUN-STUDY(NCT03628807) and analysed their relationship with mortality and sex. Propensity score for age, MELD, etiology and TIPS indication was used.

RESULTS

Cystatin C and BTP showed excellent correlations with creatinine values at baseline and follow-up. CysC was an independent predictor of overall mortality (HR = 1.66(1.33-2.06)) with an AUC of 0.75 and identified a cut-off of 1.55 mg/L in the whole cohort. Interestingly, CysC was significantly lower in females, also after propensity score matching. In males, the only independent predictor was the creatinine level (HR = 1.54(1.25-1.58)), while in females CysC levels independently predicted mortality (HR = 3.17(1.34-7.52)).

CONCLUSION

This study demonstrates for the first time that in TIPS-patients creatinine predicts mortality in males better than in females, whereas CysC is a better predictor of mortality in females. These results may influence future clinical decisions on therapeutic options for example, allocation for liver transplantation in TIPS-patients.