The fatty liver index as a predictor of incident chronic kidney disease in a 10-year prospective cohort study

Comparative effectiveness of sodium-glucose cotransporter-2 inhibitors and dipeptidyl peptidase-4 inhibitors in improvement of fatty liver index in patients with type 2 diabetes mellitus and metabolic dysfunction-associated steatotic liver disease: A retrospective nationwide claims database study in Japan

AIM

To date, there are limited clinical studies and real-world evidence investigating whether sodium-glucose cotransporter-2 inhibitors (SGLT2i) are associated with improved hepatic steatosis. This study aimed to evaluate the effectiveness of SGLT2i compared with that of dipeptidyl peptidase-4 inhibitors (DPP4i) in improving the fatty liver index (FLI) in patients with type 2 diabetes mellitus (T2DM) and metabolic dysfunction-associated steatotic liver disease (MASLD).

MATERIALS AND METHODS

This retrospective cohort study included new users of SGLT2i or DPP4i with T2DM and MASLD from a large claims database (JMDC Claims Database). The primary outcome was the incidence of improvement of the FLI. Cox proportional hazard models, weighted using propensity scores for predicting the initiation of treatment, were fitted to estimate hazard ratios with 95% confidence intervals (CIs). Time-course changes in the FLI values were also assessed.

RESULTS

This study included 9127 SGLT2i and 12 286 DPP4i initiators. SGLT2i showed a higher incidence of improvement in the FLI (≥30%, ≥40% and ≥50% reduction from baseline FLI) compared with DPP4i, and the weighted hazard ratios were 1.27 (95% CI 1.18-1.38), 1.24 (95% CI 1.13-1.37) and 1.19 (95% CI 1.05-1.33), respectively. SGLT2i indicated a greater decreased in FLI values compared with DPP4i at up to 3 years of the follow-up period.

CONCLUSION

SGLT2is use appeared to be associated with a greater improvement of the FLI than DPP4i use in patients with T2DM and MASLD. In the absence of direct head-to-head comparisons from clinical studies, our study, using real-world data, may support physicians' decision-making in clinical practice.

Prediction and Validation of Metabolic Dysfunction-Associated Fatty Liver Disease Using Fatty Liver-Related Indices in a Japanese Population

Background: Recently, metabolic dysfunction-associated fatty liver disease (MAFLD) has been proposed. It is uncertain how indices that predict fatty liver are associated with MAFLD in Japanese. Methods: Among subjects who underwent a health examination at our hospital, 1257 (men: 787, women: 474) subjects participated in fatty liver evaluation of the fatty liver index (FLI) and fatty liver predicting index (FLPI) were included in this cross-sectional study. The discriminatory ability of each index for MAFLD was tested using receiver operating characteristic curve analysis. The association between FLI, FLPI, and MAFLD was investigated using multiple logistic regression analysis. Results: FLI and FLPI had good discriminatory ability for identifying MAFLD in both men and women, with specific cutoff values. Both FLI and FLPI were significantly higher in subjects with MAFLD, and the odds of MAFLD were higher among those in the highest tertile relative to the lowest tertile in both men and women. FLI and FLPI were higher in subjects who met the criteria for both MAFLD and metabolic syndrome (MetS) compared to those who had MAFLD or MetS alone, and most of the examined parameters in subjects with both conditions indicated a high metabolic risk profile. Conclusions: The study suggests that FLI and FLPI are valuable tools for predicting MAFLD and are similarly correlated with the disease. Furthermore, the highest values of these indices were observed in subjects who met the criteria for both MAFLD and MetS, emphasizing the importance of considering both conditions when assessing metabolic risk.

Fatty liver index (FLI): more than a marker of hepatic steatosis

Fatty liver index (FLI) was developed as a simple and accurate marker of hepatic steatosis. FLI is derived from an algorithm based on body mass index, waist circumference, and levels of triglycerides and gamma-glutamyltransferase, and it is widely used in clinical and epidemiological studies as a screening tool for discriminating between healthy and nonalcoholic fatty liver disease (NAFLD) subjects. However, a systematic review of the literature regarding FLI revealed that this index has more extensive relationships with biochemical and physiological parameters. FLI is associated with key parameters of lipid, protein and carbohydrate metabolism, hormones, vitamins and markers of inflammation, or oxidative stress. FLI can be a predictor or risk factor for a number of metabolic and nonmetabolic diseases and mortality. FLI is also used as an indicator for determining the effects of health-related prevention interventions, medications, and toxic substances on humans. Although in most cases, the exact mechanisms underlying these associations have not been fully elucidated, they are most often assumed to be mediated by insulin resistance, inflammation, and oxidative stress. Thus, FLI may be a promising marker of metabolic health due to its multiple associations with parameters of physiological and pathological processes. In this context, the present review summarizes the data from currently available literature on the associations between FLI and biochemical variables and physiological functions. We believe that this review will be of interest to researchers working in this area and can provide new perspectives and directions for future studies on FLI.

The Intersection of Genetic Factors, Aberrant Nutrient Metabolism and Oxidative Stress in the Progression of Cardiometabolic Disease

Cardiometabolic disease (CMD), which encompasses metabolic-associated fatty liver disease (MAFLD), chronic kidney disease (CKD) and cardiovascular disease (CVD), has been increasing considerably in the past 50 years. CMD is a complex disease that can be influenced by genetics and environmental factors such as diet. With the increased reliance on processed foods containing saturated fats, fructose and cholesterol, a mechanistic understanding of how these molecules cause metabolic disease is required. A major pathway by which excessive nutrients contribute to CMD is through oxidative stress. In this review, we discuss how oxidative stress can drive CMD and the role of aberrant nutrient metabolism and genetic risk factors and how they potentially interact to promote progression of MAFLD, CVD and CKD. This review will focus on genetic mutations that are known to alter nutrient metabolism. We discuss the major genetic risk factors for MAFLD, which include Patatin-like phospholipase domain-containing protein 3 (PNPLA3), Membrane Bound O-Acyltransferase Domain Containing 7 (MBOAT7) and Transmembrane 6 Superfamily Member 2 (TM6SF2). In addition, mutations that prevent nutrient uptake cause hypercholesterolemia that contributes to CVD. We also discuss the mechanisms by which MAFLD, CKD and CVD are mutually associated with one another. In addition, some of the genetic risk factors which are associated with MAFLD and CVD are also associated with CKD, while some genetic risk factors seem to dissociate one disease from the other. Through a better understanding of the causative effect of genetic mutations in CMD and how aberrant nutrient metabolism intersects with our genetics, novel therapies and precision approaches can be developed for treating CMD.

Fatty Liver Index as a proxy for non-alcoholic fatty liver disease and the risk of stroke and coronary heart disease: The Suita Study

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in developed countries, but its role in predicting cardiovascular disease (CVD) needs further investigation. Herein, we studied the association between NAFLD and the risk of CVD, stroke, and coronary heart disease (CHD) among Japanese people.

METHODS

This prospective cohort study analyzed data from 2,517 men and 3,958 women, aged 30-84 years, who were registered in the Suita Study. NAFLD was defined as Fatty Liver Index (FLI) ≥ 60. Cox proportional hazard models were applied to calculate the hazard ratios (HRs) and 95% confidence intervals (95% CIs) of incident CVD, stroke, and CHD events by baseline FLI. The results were adjusted for age, smoking, alcohol consumption, hypertension, diabetes, lipid profile, chronic kidney disease, and cardiac murmur or valvular diseases.

RESULTS

Within 16.6 years of median follow-up, 590 participants developed CVD (346 stroke events and 244 CHD events). Women with NAFLD (FLI ≥ 60) showed a higher risk of CVD and stroke: HRs (95% CIs) = 1.69 (1.16, 2.46) and 2.06 (1.31, 3.24), respectively. Besides, women in the fourth and fifth (highest) FLI quintiles showed a higher risk of CVD and stroke than those in the third (middle) quintile: HRs (95% CIs) = 1.60 (1.08, 2.36) and 1.67 (1.13, 2.45) for CVD and 1.73 (1.07, 2.79) and 1.90 (1.18, 3.05) for stroke, respectively. No corresponding associations were detected in men. NAFLD was not associated with CHD risk in either sex.

CONCLUSIONS

NAFLD, diagnosed by FLI, was associated with a higher risk of CVD and stroke in Japanese women. From a preventive perspective, women with NAFLD should be targeted for CVD screenings and interventions.

Fatty Liver Index (FLI) Identifies Not Only Individuals with Liver Steatosis but Also at High Cardiometabolic Risk

A fatty liver index (FLI) greater than sixty (FLI ≥ 60) is an established score for metabolic dysfunction-associated steatotic liver disease (MASLD), which carries a high risk for diabetes and cardiovascular disease, while a FLI ≤ 20 rules out the presence of steatosis. Thus, we investigated whether FLI was associated with cardiometabolic risk factors, i.e., visceral (VAT), subcutaneous (SC), epicardial (EPI), extrapericardial (PERI), and total cardiac (CARD-AT) adipose tissue, hepatic fat ((by magnetic resonance imaging, MRI, and spectroscopy, MRS), and insulin resistance (IR, HOMA-IR and OGIS-index), and components of metabolic syndrome. All individuals with FLI ≥ 60 had MASLD, while none with FLI ≤ 20 had steatosis (by MRS). Subjects with FLI ≥ 60 had a higher BMI and visceral and cardiac fat (VAT > 1.7 kg, CARD-AT > 0.2 kg). FLI was positively associated with increased cardiac and visceral fat and components of metabolic syndrome. FLI, VAT, and CARD-AT were all associated with IR, increased blood pressure, cholesterol, and reduced HDL. For FLI ≥ 60, the cut-off values for fat depots and laboratory measures were estimated. In conclusion, FLI ≥ 60 identified not only subjects with steatosis but also those with IR, abdominal and cardiac fat accumulation, increased blood pressure, and hyperlipidemia, i.e., those at higher risk of cardiometabolic diseases. Targeted reduction of FLI components would help reduce cardiometabolic risk.

Non-alcoholic fatty liver disease fibrosis score is a useful index for predicting all-cause mortality in patients with antineutrophil cytoplasmic antibody-associated vasculitis

Background

This study investigated whether the non-alcoholic fatty liver disease fibrosis score (NFS) could predict all-cause mortality during follow-up among patients with antineutrophil cytoplasmic antibody-associated vasculitis (AAV).

Methods

The medical records of 256 AAV patients were retrospectively reviewed. AAV patients with clinically critical chronic liver diseases were excluded. NFS was calculated using the following equation: NFS = -1.675 + 0.037 - age + 0.094 - body mass index +1.13 × impaired fasting glucose/diabetes mellitus +0.99 × aspartate aminotransferase/alanine aminotransferase ratio - 0.013 × platelet count - 0.66 × serum albumin.

Results

The median age was 59.0 years, and 35.2% of the patients were male. The median Birmingham Vasculitis Activity Score (BVAS), five-factor score (FFS), and NFS were 12.0, 1.0, and - 4.7, respectively. Of the 256 patients, 33 (12.9%) died. Using the receiver operating characteristic curve, the optimal cut-off of NFS for all-cause mortality was obtained as-3.97. AAV patients with NFS at diagnosis ≥ - 3.97 exhibited a lower cumulative patients' survival rate than those with NFS at diagnosis <-3.97. The multivariable Cox analysis revealed that NFS at diagnosis ≥ - 3.97 (HR 2.232, 95% CI 1.011, 4.925) was independently associated with all-cause mortality in AAV patients.

Conclusion

This study was the first to demonstrate that NFS at AAV diagnosis was clinically useful in predicting all-cause mortality during follow-up, regardless of both the degree of liver fibrosis and abnormal or normal liver function results.

Metabolic-associated fatty liver disease increases the risk of end-stage renal disease in patients with biopsy-confirmed diabetic nephropathy: a propensity-matched cohort study

AIMS

To investigate the relationship between metabolic-associated fatty liver disease (MAFLD) and end-stage renal disease (ESRD) in patients with biopsy-confirmed diabetic nephropathy (DN).

METHODS

A total of 316 participants with biopsy-confirmed DN between January 2008 and December 2019 were retrospectively assessed. Kaplan-Meier curve and Cox proportional hazard models were used to compare the risk of incident ESRD in 50 patients with MAFLD and 50 patients without MAFLD, after using propensity score matching (PSM) to address the imbalances of sex, age, baseline-estimated glomerular filtration rate, serum albumin, 24-h urine protein, hemoglobin and systolic blood pressure.

RESULTS

During the median follow-up period of 3 years, there were 19 ESRD outcome events (19%) in PSM cohort. Kaplan-Meier curve analysis suggested that renal survival significantly deteriorated in patients with MAFLD versus those without MAFLD (p = 0.021). Additionally, the hazard ratios (95% confidence interval) of MAFLD were 3.12 (1.09-8.95, p = 0.035), 3.36 (1.09-10.43, p = 0.036), 3.66 (1.22-10.98, p = 0.021), 4.25 (1.34-13.45, p = 0.014), 3.11 (1.08-8.96, p = 0.035) and 5.84 (1.94-18.5, p = 0.003) after adjustment for six models, including demographic, clinical and pathological characteristics as well as medication use at the time of renal biopsy, respectively. Besides, patients with higher liver fibrosis score had a greater possibility of ESRD, comparing to those with lower liver fibrosis score (p = 0.002).

CONCLUSIONS

MAFLD increases the risk of incident ESRD in patients with biopsy-proven DN. Further research is needed to determine whether treatment targeting MAFLD improves the prognosis of DN.

Liver steatosis and fibrosis markers' association with cardiovascular and renal damage in Japanese adults: the TMM BirThree cohort study

INTRODUCTION AND OBJECTIVES

Patients with non-alcoholic fatty liver disease (NAFLD) are at risk for cardiovascular and chronic kidney diseases. Liver steatosis and fibrosis were assessed using the fatty liver index and fibrosis-4 index, respectively. This study aimed to examine the association between these two parameters in patients with atherosclerosis and chronic kidney disease.

MATERIALS AND METHODS

The two parameters were calculated for 11,867 adults who participated in the Tohoku Medical Megabank Project Birth and Three-Generation Cohort Study. Intima-media thickness and estimated glomerular filtration rate were also measured. Logistic regression models were used to estimate the odds ratios (OR).

RESULTS

Overall, 4257 (35.9%) and 4733 (39.9%) participants had a higher probability of liver steatosis and fibrosis, respectively. The adjusted OR of higher fatty liver index compared to lower fatty liver index for atherosclerosis and chronic kidney disease were 0.98 (95% confidence interval [CI], 0.77-1.24) and 1.79 (95% CI, 1.19-2.69), and those of higher FIB-4 compared to lower FIB-4 were 1.03 (95% CI, 0.82-1.30) and 0.79 (95% CI, 0.52-1.19) for atherosclerosis and chronic kidney disease, respectively.

CONCLUSIONS

A higher FLI was associated with CKD independent of other risk factors. Further research is required to identify the causal relationship between liver fat accumulation and CKD.

2019 Global NAFLD Prevalence: A Systematic Review and Meta-analysis

BACKGROUND & AIMS

The increasing rates of obesity and type 2 diabetes mellitus may lead to increased prevalence of nonalcoholic fatty liver disease (NAFLD). We aimed to determine the current and recent trends on the global and regional prevalence of NAFLD.

METHODS

Systematic search from inception to March 26, 2020 was performed without language restrictions. Two authors independently performed screening and data extraction. We performed meta-regression to determine trends in NAFLD prevalence.

RESULTS

We identified 17,244 articles from literature search and included 245 eligible studies involving 5,399,254 individuals. The pooled global prevalence of NAFLD was 29.8% (95% confidence interval [CI], 28.6%-31.1%); of these, 82.5% of included articles used ultrasound to diagnose NAFLD, with prevalence of 30.6% (95% CI, 29.2%-32.0%). South America (3 studies, 5716 individuals) and North America (4 studies, 18,236 individuals) had the highest NAFLD prevalence at 35.7% (95% CI, 34.0%-37.5%) and 35.3% (95% CI, 25.4%-45.9%), respectively. From 1991 to 2019, trend analysis showed NAFLD increased from 21.9% to 37.3% (yearly increase of 0.7%, P < .0001), with South America showing the most rapid change of 2.7% per year, followed by Europe at 1.1%.

CONCLUSIONS

Despite regional variation, the global prevalence of NAFLD is increasing overall. Policy makers must work toward reversing the current trends by increasing awareness of NAFLD and promoting healthy lifestyle environments.

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.

Non-alcoholic fatty liver disease and sarcopenia is associated with the risk of albuminuria independent of insulin resistance, and obesity

BACKGROUND

Although non-alcoholic fatty liver disease (NAFLD) is associated with metabolic disorders, its influence on albuminuria has not been determined. The aim of this study was to identify the relationship between NAFLD and albuminuria in the general Korean population.

METHODS

Data from the Korea National Health and Nutrition Examination Surveys (KNHANES) of 2008-2011 were analyzed (n = 1795). Albuminuria was defined as an albumin-to-creatinine ratio of ≥30 mg/g in random spot urine samples. NAFLD was defined as a fatty liver index (FLI) ≥60 or NAFLD liver fat score (LFS) > -0.64.

RESULTS

A total of 289 (16.1 %) subjects were classified as having albuminuria. Subjects with NAFLD exhibited a higher rate of albuminuria than subjects without NAFLD (crude odds ratios [ORs] = 2.60-2.95, all P < 0.001). Regardless of hypertension, insulin resistance, or obesity, the risk for albuminuria was higher in the NAFLD group than in the group without NAFLD (measured by either FLI or LFS; all P < 0.001). When subjects with NAFLD had sarcopenia, the risk of albuminuria further increased (OR = 4.33-4.64, all P < 0.001). Multiple logistic regression analyses also demonstrated that NAFLD was independently associated with albuminuria (OR = 2.58, 95 % confidence interval [CI] = 1.66-4.02, P < 0.001 for FLI, OR = 1.87, 95 % CI = 1.28-2.75, P = 0.001 for LFS).

CONCLUSIONS

NAFLD was associated with an increased risk of albuminuria in the general Korean population. This association was independent of hypertension, insulin resistance, chronic kidney disease, diabetes and obesity, and stronger in subjects with sarcopenia.

High fatty liver index is an independent predictor of ischemic heart disease during a 10-year period in a Japanese population

AIM

Fatty liver index (FLI), which is calculated by using body mass index, waist circumference and levels of γ-glutamyl transferase and triglycerides, is a validated surrogate marker of nonalcoholic fatty liver disease. We retrospectively investigated the relationship between FLI and the development of ischemic heart disease (IHD) during a 10-year period.

METHODS

Among subjects who received annual health checkups (n = 28 990), a total of 18 851 subjects (men/women: 11 659/7192) were enrolled after exclusion of subjects with missing data and those with IHD at baseline.

RESULTS

FLI at baseline was significantly higher in men than in women. During the 10-year period, 450 men (3.9%) and 123 women (1.7%) had new onset of IHD determined by a self-reported questionnaire survey. Multivariable Cox proportional hazard models with a restricted cubic spline showed that hazard risk (HR) for the development of IHD increased with a higher FLI at baseline after adjustment of age, sex, current smoking habit, family history of IHD and diagnosis of diabetes mellitus, hypertension, dyslipidemia and chronic kidney disease at baseline. There was no significant interaction between FLI and sex for the adjusted HR. When divided by tertiles of FLI at baseline (T1∼T3), the adjusted risk for development of IHD in the T3 group (HR [95% confidence interval]: 1.34 [1.05-1.71]) was significantly higher than that in the T1 group as the reference. The addition of FLI into traditional risk factors for IHD significantly improved the discriminatory capability.

CONCLUSIONS

A high level of FLI is an independent predictor of new onset of IHD during a 10-year period.

Crosstalk between kidney and liver in non-alcoholic fatty liver disease: mechanisms and therapeutic approaches

Liver and kidney are vital organs that maintain homeostasis and injury to either of them triggers pathogenic pathways affecting the other. For example, non-alcoholic fatty liver disease (NAFLD) promotes the progression of chronic kidney disease (CKD), vice versa acute kidney injury (AKI) endorses the induction and progression of liver dysfunction. Progress in clinical and basic research suggest a role of excessive fructose intake, insulin resistance, inflammatory cytokines production, activation of the renin-angiotensin system, redox imbalance, and their impact on epigenetic regulation of gene expression in this context. Recent developments in experimental and clinical research have identified several biochemical and molecular pathways for AKI-liver interaction, including altered liver enzymes profile, metabolic acidosis, oxidative stress, activation of inflammatory and regulated cell death pathways. This review focuses on the current preclinical and clinical findings on kidney-liver crosstalk in NAFLD-CKD and AKI-liver dysfunction settings and highlights potential molecular mechanisms and therapeutic targets.

Prediction and validation of nonalcoholic fatty liver disease by fatty liver index in a Japanese population

Fatty liver index (FLI) calculated by using body mass index (BMI), waist circumference and levels of γ-glutamyl transferase and triglycerides is a non-invasive predictor of nonalcoholic fatty liver disease (NAFLD). The original study in Italy showed that the cutoff level for prediction of NAFLD was FLI ≥60. However, the sex difference in FLI was not taken into consideration, and it is unclear whether the cutoff value can be applied to other races. We investigated the cutoff value of FLI for prediction of NAFLD determined by abdominal ultrasonography using receiver operating characteristic curve analyses in 14,471 Japanese subjects (men/women: 9,240/5,231; mean age: 48 ± 9 years). There was a significant interaction between sex and FLI for detection of NAFLD (p < 0.001). The cutoff values of FLI in men and women were 35.1 (area under the curve [AUC]: 0.82) and 15.6 (AUC: 0.91), respectively. When the subjects were divided by the absence and presence of obesity (BMI ≥25), there was a significant interaction between FLI and obesity for detection of NAFLD in women (p < 0.001) but not in men (p = 0.679). The cutoff values of FLI in non-obese/obese men and women were 22.6/52.6 and 11.2/33.2, respectively. In conclusion, the cutoff value of FLI for prediction of NAFLD in Japanese individuals was lower than that in the original study, and there is a significant sex difference. The simple and useful cutoff values in Japanese men and women are FLI ≥35 (non-obese/obese: 23/53) and FLI ≥16 (non-obese/obese: 11/33), respectively.

Prognosis of Chronic Kidney Disease in Patients with Non-Alcoholic Fatty Liver Disease: a Northeastern Taiwan Community Medicine Research Cohort

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is associated with incident chronic kidney disease (CKD). We aimed to investigate outcomes and risk factors of CKD progression and regression.

METHODS

This is a longitudinal community-based cohort study of patients with NAFLD. Exclusion criteria included alcoholic liver diseases, sero-positive for hepatitis B surface antigen, sero-positive for hepatitis C virus antibodies, fatty liver index < 60, individuals with only one year of data, missing data for fibrosis-4 score and NAFLD fibrosis score, and advanced CKD at baseline. Main outcomes were stratified according to eGFR and albuminuria categories as state 1 (low risk), state 2 (moderately increased risk), and state 3 (high-risk/very-high risk of progression). The multi-state Markov model was used for outcome analysis.

RESULTS

This study included 1,628 patients with NAFLD with a median follow-up of 3.4 years. State 2 CKD was found in 9.3% of patients at 5 years (95% CI, 8.1%-10.6%). Most patients with state 2 CKD recovered to state 1 (69%; 95% CI, 63.7%-74%), while 17.6% progressed to state 3 (95% CI, 13.4%- 22.7%). Advanced liver fibrosis was found to be associated with the risk of transitioning from state 1 to state 2 (Fibrosis-4 score ≥1.3; hazard ratio [HR], 1.42; 95% CI, 1.02-2.00), and reduced recovery from state 2 to state 1 (NAFLD fibrosis score; NFS≥-1.455; HR, 0.56; 95% CI, 0.34-0.91).

CONCLUSIONS

NAFLD severity is associated with CKD, which may be reversible before becoming high-risk. Controlling metabolic risk factors and preventing advanced liver fibrosis are recommended.

Association between the fatty liver index and the risk of severe complications in COVID-19 patients: a nationwide retrospective cohort study

Background

Research on the association of non-alcoholic fatty liver disease (NAFLD) with prognosis in COVID-19 has been limited. We investigated the association between the fatty liver index (FLI), a non-invasive and simple marker of NAFLD, and the severe complications of COVID-19 patients in South Korea.

Methods

We included 3122 COVID-19-positive patients from the nationwide COVID-19 cohort dataset in South Korea between January and June 2020. The FLI was calculated using triglyceride, body mass index, glutamyl transpeptidase, and waist circumference, which were obtained from the national health screening program data. Severe complications related to COVID-19 were defined as the composite of mechanical ventilation, intensive care unit treatment, high-oxygen flow therapy, and death within 2 months after a COVID-19 infection. We performed a multivariate logistic regression analysis for the development of severe complications in COVID-19 patients.

Results

The mean ± standard deviation of FLI were 25.01 ± 22.64. Severe complications from COVID-19 occurred in 223 (7.14%) patients, including mechanical ventilation in 82 (2.63%) patients, ICU admission in 126 (4.04%), high-flow oxygen therapy in 75 (2.40%), and death in 94 (3.01%) patients, respectively. The multivariate analysis indicated that the highest tertile (T3) of FLI was positively associated with severe complications from COVID-19 (adjusted odds ratio (OR): 1.77, 95% confidence interval (CI) (1.11–2.82), P = 0.017) compared with the lowest tertile (T1).

Conclusions

Our study demonstrated that FLI, which represents NAFLD, was positively associated with an increased risk of severe complications from COVID-19. FLI might be used as a prognostic marker for the severity of COVID-19.

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.

Non-alcoholic Fatty Liver Disease and the Risk of Incident Atrial Fibrillation in Young Adults: A Nationwide Population-Based Cohort Study

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is a multisystem disease including cardiovascular. However, the association between NAFLD and the risk of incident atrial fibrillation (AF), especially in young adults, remains unclear. We aimed to evaluate the association between NAFLD as assessed by the fatty liver index (FLI) and the risk of AF in young adults.

METHODS

We identified individuals aged 20-39 years who underwent health examinations conducted by the Korean National Health Insurance Corporation between January 2009 and December 2012. Individuals with significant liver disease, heavy alcohol consumption, or prevalent AF were excluded. We categorized based on FLI: <30, 30 to <60, and ≥60. Incident AF was evaluated as the primary outcome.

RESULTS

We included 5,333,907 subjects (mean age, 31 ± 5 years; men, 57%). During a mean follow-up of 7.4 ± 1.1 years, 12,096 patients had newly diagnosed AF (incidence rate 0.31 per 1,000 person-years). After adjustment, subjects with FLI 30 to <60 and FLI ≥60 showed a higher risk of AF compared to those with FLI <30 (hazard ratio [HR] 1.21, 95% confidence interval [CI, 1.15-1.27] and HR 1.47, 95% CI [1.39-1.55], p < 0.001, respectively). In women, the increased AF risk was accentuated in the higher FLI group than in the individuals with FLI <30, compared with men (p-for-interaction = 0.023). A higher incident AF risk in the higher FLI groups was consistently observed in various subgroups.

CONCLUSION

Among young adults, NAFLD assessed using FLI was positively correlated with the AF risk. These findings support the evidence of AF screening in young adults with high FLI scores.

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.

Independent Association of Fatty Liver Index With Left Ventricular Diastolic Dysfunction in Subjects Without Medication

Nonalcoholic fatty liver disease has been reported to be potentially linked to cardiovascular disease. Fatty liver index (FLI) is a noninvasive and simple predictor of nonalcoholic fatty liver disease. However, little is known about the relationship between FLI and cardiac function, especially in a general population. We investigated the relationships of FLI with echocardiographic parameters in 185 subjects (men/women: 79/106) of the Tanno-Sobetsu Study, a population-based cohort, who were not being treated with any medication and who underwent echocardiography. FLI was negatively correlated with high-density lipoprotein cholesterol and peak myocardial velocity during early diastole (e'; r = -0.342, p <0.001), an index of left ventricular (LV) diastolic function, and ratio of peak mitral velocities during early and late diastole (E/A) and was positively correlated with age, systolic and diastolic blood pressures, creatinine, uric acid, homeostasis model assessment of insulin resistance, high-sensitivity C-reactive protein, ratio of mitral to myocardial early diastolic peak velocity (E/e'), left atrial volume index and LV mass index. No significant correlation was found between FLI and LV ejection fraction. Stepwise multivariable regression analysis showed that FLI was independently and negatively associated with e' after adjustment of age, gender, high-density lipoprotein cholesterol, homeostasis model assessment of insulin resistance, and high-sensitivity C-reactive protein. Conversely, e' was independently and negatively associated with FLI after adjustment of age, gender, systolic blood pressure, and LV ejection fraction. In conclusion, elevated FLI is independently associated with LV diastolic dysfunction in a general population without medication. FLI would be a novel marker of LV diastolic dysfunction as an early sign of myocardial injury.

Nonalcoholic Fatty Liver Disease and the Kidney: A Review

Nonalcoholic fatty liver disease (NAFLD) is associated with several extrahepatic manifestations such as cardiovascular disease and sleep apnea. Furthermore, NAFLD is reported to be associated with an increased risk of incident chronic kidney disease (CKD). Inflammation and oxidative stress are suggested to be the key factors involved in the inflammatory mechanisms and pathways linking NAFLD to CKD and are responsible for both the pathogenesis and the progression of CKD in NAFLD patients. This review aims to provide a more comprehensive overview of the association between CKD and NAFLD, also considering the effect of increasing severity of NAFLD. A PubMed search was conducted using the terms "non-alcoholic fatty liver disease AND kidney". In total, 537 articles were retrieved in the last five years and 12 articles were included in the qualitative analysis. Our results showed that CKD developed more frequently in NAFLD patients compared to those without NAFLD. This association persisted after adjustment for traditional risk factors and according to the severity of NAFLD. Therefore, patients with NAFLD should be considered at high risk of CKD. Intensive multidisciplinary surveillance over time is needed, where hepatologists and nephrologists must act together for better and earlier treatment of NAFLD patients.

Circulating PCSK7 Level is Independently Associated with Obesity, Triglycerides Level and Fatty Liver Index in a General Population without Medication

AIM

Dyslipidemia and altered iron metabolism are typical features of non-alcoholic fatty liver disease (NAFLD). Proprotein convertase subtilisin/kexin type 7 (PCSK7), a transmembrane-anchored endonuclease, is associated with triglycerides level and processing of transferrin receptor 1. However, the significance of circulating PCSK7 has not been fully addressed, though prosegment PCSK7 is secreted from cells. We investigated the associations of plasma PCSK7 level with several parameters.

METHODS

Plasma PCSK7 concentration was measured in 282 subjects (male/female: 126/156) without medication of the Tanno-Sobetsu Study, a population-based cohort study.

RESULTS

There was no significant sex difference in PCSK7 level. Current smoking habit, but not alcohol drinking habit, was associated with increased PCSK7 level. PCSK7 concentration was negatively correlated with age and blood urea nitrogen and was positively correlated with body mass index (BMI) and levels of γ-glutamyl transpeptidase (γGTP), triglycerides and fatty liver index (FLI), which is calculated by BMI, waist circumference and levels of γGTP and triglycerides, as a noninvasive and simple predictor of NAFLD. There were no significant correlations of PCSK7 level with levels of iron and plasma PCSK9, a secreted PCSK family member and a regulator of low-density lipoprotein cholesterol level. Multivariable regression analyses after adjustment of age, sex and current smoking habit showed that PCSK7 concentration was independently associated with BMI (β=0.130, P=0.035), triglycerides (β=0.141, P=0.027) or FLI (β=0.139, P=0.030).

CONCLUSIONS

Plasma PCSK7 concentration is independently associated with chronic liver disease including obesity and elevated triglycerides level in a general population of individuals who had not regularly taken any medications.

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.

Non-alcoholic fatty liver and chronic kidney disease: Retrospect, introspect, and prospect

With the growing prevalence of obesity and diabetes in the United States and across the world, a rise in the overall incidence and prevalence of non-alcoholic fatty liver disease (NAFLD) is expected. The risk factors for NAFLD are also associated with the development of chronic kidney disease (CKD). We review the epidemiology, risk factors, genetics, implications of gut dysbiosis, and specific pathogenic mechanisms linking NAFLD to CKD. Mechanisms such as ectopic lipid accumulation, cellular signaling abnormalities, and the interplay between fructose consumption and uric acid accumulation have led to the emergence of potential therapeutic implications for this patient population. Transplant evaluation in the setting of both NAFLD and CKD is also reviewed. Potential strategies for surveillance and management include the monitoring of comorbidities, the use of non-invasive fibrosis scoring systems, and the measurement of laboratory markers. Lastly, we discuss the management of patients with NAFLD and CKD, from preventative measures to experimental interventions.

Advances in the Management of Renal Dysfunction in Patients With Cirrhosis

Renal dysfunction frequently develops in patients with advanced liver disease. Renal dysfunction in this setting is associated with adverse outcomes and an unfavorable prognosis. Hepatorenal syndrome (HRS), defined as worsening renal function in patients with advanced cirrhosis that can present either acutely (<3 months) or more indolently in the absence of other etiologies, remains a common cause of acute kidney injury. If reversal is not promptly achieved, rapid decline to mortality is common. Volume expansion and vasoconstrictors are the mainstays of therapy. Terlipressin, a vasopressin analogue licensed in several countries but not in the United States, is currently used for the treatment of HRS. Timely liver transplantation remains the only effective therapeutic option for a large group of patients with persistent renal dysfunction despite pharmacotherapy. In patients with underlying chronic renal dysfunction, simultaneous liver-kidney transplantation should be considered. The aim of this article is to present an overview of renal dysfunction in patients with cirrhosis, including diagnosis and management.

Performance of Fatty Liver Index in Identifying Non-Alcoholic Fatty Liver Disease in Population Studies. A Meta-Analysis

Background. Fatty liver index (FLI) is a non-invasive tool used to stratify the risk of non-alcoholic fatty liver disease (NAFLD) in population studies; whether it can be used to exclude or diagnose this disorder is unclear. We conducted a meta-analysis to assess the prevalence of NAFLD in each FLI class and the performance of FLI in detecting NAFLD. Methods. Four databases were searched until January 2021 (CRD42021231367). Original articles included were those reporting the performance of FLI and adopting ultrasound, computed tomography, or magnetic resonance as a reference standard. The numbers of subjects with NAFLD in FLI classes <30, 30–60, and ≥60, and the numbers of subjects classified as true/false positive/negative when adopting 30 and 60 as cut-offs were extracted. A random-effects model was used for pooling data. Results. Ten studies were included, evaluating 27,221 subjects without secondary causes of fatty liver disease. The prevalence of NAFLD in the three FLI classes was 14%, 42%, and 67%. Sensitivity, specificity, positive predictive value, negative predictive value, likelihood ratio for positive results, likelihood ratio for negative results, and diagnostic odds ratio were 81%, 65%, 53%, 84%, 2.3, 0.3, and 7.8 for the lower cut-off and 44%, 90%, 67%, 76%, 4.3, 0.6, and 7.3 for the higher cut-off, respectively. A similar performance was generally found in studies adopting ultrasound versus other imaging modalities. Conclusions. FLI showed an adequate performance in stratifying the risk of NAFLD. However, it showed only weak evidence of a discriminatory performance in excluding or diagnosing this disorder.

Fatty liver index is independently associated with deterioration of renal function during a 10-year period in healthy subjects

A potential link between chronic kidney disease (CKD) and non-alcoholic fatty liver disease (NAFLD) has been suggested. We investigated the relationship between fatty liver index (FLI), a noninvasive and simple predictor of NAFLD, and the development of CKD defined as estimated glomerular filtration rate < 60 mL/min/1.73 m² or positive for urinary protein during a 10-year follow-up period in subjects who received annual health examinations (n = 28,890). After exclusion of CKD at baseline, a total of 14,163 subjects (male/female: 9077/5086) were recruited. During the 10-year period, 1458 males (16.1%) and 737 females (14.5%) had new onset of CKD. Multivariable Cox proportional hazard models with a restricted cubic spline showed that hazard ratios (HRs) of CKD development increased with a higher FLI at baseline in both males and females after adjustment of confounders. When divided by tertiles of FLI level at baseline (T1 ~ T3), the adjusted risk of CKD development in the T3 group (HR [95% confidence interval], male/female: 1.33 [1.16–1.54]/1.33 [1.08–1.63]) was significantly higher than that in both sexes in the T1 group as the reference. The addition of FLI into traditional risk factors significantly improved the discriminatory capability for predicting CKD. In conclusion, a high level of FLI predicts the development of CKD in both sexes in a general population.

Effect of body shape on the development of cardiovascular disease in individuals with metabolically healthy obesity

Studies about the effects of metabolically healthy obesity on cardiovascular disease (CVD) have yielded conflicting results. These heterogeneous results could be due to the limited usefulness of BMI in measuring general adiposity, as body mass index (BMI) does not accurately reflect body composition. This study aimed to evaluate the effect of body shape on CVD outcomes across different obesity phenotypes, and to provide an explanation for the heterogeneous effects of metabolically healthy obese (MHO) phenotype on CVD.We analyzed data from the Korean Genome and Epidemiology Study, a population-based cohort study conducted between 2001 and 2012. We divided the participants into 4 groups: metabolically healthy non-obese (MHNO), MHO, metabolically unhealthy non-obese (MUNO), and metabolically unhealthy obese (MUO). To assess body shape, we calculated the z-score of the log-transformed a body shape index (LBSIZ). We computed Pearson correlation coefficients to examine the association of LBSIZ with muscle mass index, percentage of total fat mass (%Total FM), and percentage of abdominal fat mass (%Abdominal FM). We also used Cox proportional hazards regression to evaluate the effect of LBSIZ on CVD events according to the obesity phenotypes.A total of 9460 participants were assessed in this study. The incidence of CVD was 8.53 cases per 1000 person-year. LBSIZ showed strong positive correlation with %Total FM and %Abdominal FM, but negative correlation with muscle mass index. In Cox regression, MHO individuals did not show increased risk of CVD compared with MHNO individuals (hazard ratio [HR], 1.29; 95% confidence interval [CI], 0.96-1.73). However, MHO individuals in the 3rd (HR, 2.40; 95% CI, 1.28-4.51) and 4th (HR, 3.67; 95% CI, 1.99-6.74) quarters of LBSIZ showed significantly higher risk of CVD compared with MHNO individuals in the 1st quarter of LBSIZ. Moreover, LBSIZ showed a linear relationship with CVD among MHO individuals.While the MHO individuals showed similar CVD risk to the MHNO individuals, CVD risk increases with LBSIZ among the MHO individuals. LBSIZ appears to be a useful measure for CVD risk assessment in clinical practice and epidemiologic studies, especially for MHO patients.

Association between Non-Alcoholic Fatty Liver Disease and Chronic Kidney Disease: A Cross-Sectional Study

It is unclear whether the link between non-alcoholic fatty liver disease (NAFLD) and chronic kidney disease (CKD) is mediated by common risk factors. We aimed to elucidate the association between NAFLD and CKD using propensity score (PS)-matched analysis. We assessed 3725 Japanese individuals, excluding those with hepatitis B or C infection and men and women who consumed >30 and >20 g/day of alcohol, respectively. Of these, we enrolled 1097 Japanese subjects with NAFLD diagnosed by ultrasonography and 1097 PS-matched subjects without NAFLD. The prevalence of CKD was higher in subjects with NAFLD than in those without NAFLD before PS matching, but there was no significant difference between these groups in terms of CKD prevalence after PS matching. There was no difference in the prevalence of CKD between those with and without NAFLD in the subgroup analyses. Logistic regression analysis demonstrated that obesity, hypertension, and hyperuricemia were independent predictors of CKD, but NAFLD was not independently associated with CKD. In subjects with NAFLD, obesity, hypertension, and hyperuricemia were independent predictors of CKD. Thus, the link between NAFLD and CKD may be mediated by common risk factors. We recommend screening for CKD when patients with NAFLD have the aforementioned comorbidities.

Fatty liver index and development of cardiovascular disease in Koreans without pre-existing myocardial infarction and ischemic stroke: a large population-based study

BACKGROUND

Despite the known association between non-alcoholic fatty liver disease (NAFLD) and cardiovascular disease (CVD), whether NAFLD predicts future CVD events, especially CVD mortality, remains uncertain. We evaluated the relationship between fatty liver index (FLI), a validated marker of NAFLD, and risk of major adverse cardiac events (MACEs) in a large population-based study.

METHODS

We identified 3011,588 subjects in the Korean National Health Insurance System cohort without a history of CVD who underwent health examinations from 2009 to 2011. The primary endpoint was a composite of cardiovascular deaths, non-fatal myocardial infarction (MI), and ischemic stroke. A Cox proportional hazards regression analysis was performed to assess association between the FLI and the primary endpoint.

RESULTS

During the median follow-up period of 6 years, there were 46,010 cases of MACEs (7148 cases of cardiovascular death, 16,574 of non-fatal MI, and 22,288 of ischemic stroke). There was a linear association between higher FLI values and higher incidence of the primary endpoint. In the multivariable models adjusted for factors, such as body weight and cholesterol levels, the hazard ratio for the primary endpoint comparing the highest vs. lowest quartiles of the FLI was 1.99 (95% confidence interval [CIs], 1.91-2.07). The corresponding hazard ratios (95% CIs) for cardiovascular death, non-fetal MI, and ischemic stroke were 1.98 (1.9-2.06), 2.16 (2.01-2.31), and 2.01 (1.90-2.13), respectively (p < 0.001). The results were similar when we performed stratified analyses by age, sex, use of dyslipidemia medication, obesity, diabetes, and hypertension.

CONCLUSIONS

Our findings indicate that the FLI, which is a surrogate marker of NAFLD, has prognostic value for detecting individuals at higher risk for cardiovascular events.

PNPLA3 I148M gene variant and chronic kidney disease in type 2 diabetic patients with NAFLD: Clinical and experimental findings

BACKGROUND AND AIMS

Emerging evidence suggests an association between patatin-like phospholipase domain-containing protein-3 (PNPLA3) rs738409 (I148M protein variant) and risk of chronic kidney disease (CKD), but the mechanisms underpinning this association are poorly understood.

METHODS

We studied 157 patients with type 2 diabetes (T2DM) who underwent ultrasonography and vibration-controlled transient elastography for diagnosing nonalcoholic fatty liver disease (NAFLD). CKD was defined as estimated glomerular filtration rate (e-GFR) <60 mL/min/1.73 m² and/or abnormal albuminuria. We surveyed PNPLA3 mRNA expression in human tissues, using the liver as a positive control, and also measured PNPLA3 mRNA and protein expression levels in human cell lines represented in the kidney and the liver.

RESULTS

In all, 112 patients had NAFLD and 43 had CKD. Patients homozygous for the I148M variant (n = 11) had lower e-GFR levels (60.6 ± 11.7 vs 77.8 ± 15.9 vs 83.5 ± 16.5 mL/min/1.73 m² , P = .0001) and higher prevalence of CKD (63.6% vs 24.2% vs 25.0%, P = .028), compared to those with I/M (n = 66) and I/I (n = 80) PNPLA3 genotype. The association of I148M homozygosity with lower e-GFR levels (P < .0001) and higher risk of CKD (adjusted-odds ratio 6.65; 95% CI 1.65-26.8, P = .008) was independent of liver disease severity (as detected by liver stiffness ≥7kPa) and other risk factors. PNPLA3 mRNA expression was greatest in liver and renal cortex, and podocytes showed high PNPLA3 mRNA and protein levels, comparable to that of hepatocytes and hepatic stellate cells respectively.

CONCLUSIONS

The PNPLA3 I148M variant was associated with CKD, independently of common renal risk factors and severity of NAFLD PNPLA3 expression levels were particularly high in renal podocytes.

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.

Combined effects of lifestyle risk factors on fatty liver index

Background

Factors of lifestyle may have a major impact on liver-related morbidity and mortality.

We examined independent and joint effects of lifestyle risk factors on fatty liver index (FLI), a biomarker of hepatic steatosis, in a population-based cross-sectional national health survey.

Methods

The study included 12,368 participants (5784 men, 6584 women) aged 25–74 years. Quantitative estimates of alcohol use, smoking, adiposity and physical activity were used to establish a total score of risk factors, with higher scores indicating an unhealthier lifestyle. FLI was calculated based on an algorithm including body mass index, waist circumference, serum gamma-glutamyltransferase and triglycerides.

Results

The occurrence of FLI ≥ 60% indicating fatty liver increased from 2.4% in men with zero risk factors to 81.9% in those with a total risk score of 7–8 (p <  0.0005 for linear trend) and in women from 0 to 73.5% (p <  0.0005). The most striking individual impacts on the likelihood for FLI above 60% were observed for physical inactivity (p <  0.0005 for both genders) and alcohol consumption (p <  0.0005 for men). Interestingly, coffee consumption was also found to increase with increasing risk factor scores (p <  0.0005 for linear trend in both genders).

Conclusions

The data indicates that unfavorable combinations of lifestyle risk factors lead to a high likelihood of hepatic steatosis. Use of FLI as a diagnostic tool may benefit the assessment of interventions aimed at maintaining a healthy lifestyle and prevention of liver-related morbidity.

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.

Diagnosis and management of renal dysfunction in patients with cirrhosis

Introduction: Renal dysfunction commonly occurs in patients with cirrhosis and is typically associated with poor prognosis. Several pathophysiologic mechanisms are responsible for renal disease in these patients, prompt identification permits individualized management.Areas covered: Pathophysiology, evaluation and differential diagnosis, management and prognosis of renal disease in patients with cirrhosis. Special focus on management of hepatorenal syndrome and indications for simultaneous liver-kidney transplantation.Literature search methodology: a detailed literature search was performed using PubMed without date restrictions. Published guidelines and position papers were also used and cross-referenced to identify additional studies.Expert opinion: The prognostic significance of renal dysfunction in patients with cirrhosis is highlighted by the inclusion of serum creatinine in the model for end-stage liver disease (MELD). Both acute and chronic renal dysfunction result in increased mortality in patients with cirrhosis, although there are marked differences related to the etiology of renal disease. Early recognition and prompt intervention determined by the most likely etiology are key in the management of these patients. Simultaneous liver-kidney transplantation improves patient survival compared to isolated liver transplantation in patients with cirrhosis and persistent renal impairment; however, selection of candidates must be judicious and individualized due to the ongoing shortage of donor kidneys.

Higher NAFLD fibrosis score is associated with impaired eGFR

BACKGROUND/PURPOSE

Chronic kidney disease (CKD) has become a worldwide health problem, leading to high morbidity and mortality, and non-alcoholic fatty liver disease (NAFLD) is considered a risk factor for CKD. The aim of this study was to explore the relationship between NAFLD fibrosis score (NFS) and the estimated glomerular filtration rate (eGFR), and identify possible risk factors related to the NFS among Taiwanese subjects.

METHODS

Subjects were enrolled from the database of the Department of Preventive Medicine of Kaohsiung Municipal Hsiao-Kang Hospital. The eGFR was calculated according to the Taiwanese Modification of Diet in Renal Disease (TMDRD) equation, and the NFS was employed to evaluate the fibrotic level.

RESULTS

In total, 11,376 subjects were enrolled in this study, with a mean age of 52.0 ± 6.81 years, including 4529 (39.8%) males. A fasting sugar level ≥100 mg/dL (OR = 1.70, 95% CI = 1.52-1.87) and an abnormal waist circumference (OR = 1.81, 95% CI = 1.65-1.99) were significant factors associated with NFS (p < 0.05). Trends of a decreasing TMDRD score and an increasing NFS with increasing age were noted (p < 0.05). The NFS was significantly negatively correlated with the TMDRD score (standard coefficients: -0.067, p < 0.001).

CONCLUSION

A higher NFS is associated with an impaired eGFR in Taiwanese subjects. Controlling risk factors, especially fasting sugar level and waist circumference, may be useful in preventing NFS deterioration, which is negatively correlated with the eGFR.

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

BACKGROUND & AIMS

Prior studies demonstrated an association between non-alcoholic fatty liver disease and chronic kidney disease (CKD), though data are conflicting. We examined the association between liver fat and prevalent and incident CKD in the Framingham Heart Study (FHS).

METHODS

We included FHS participants who underwent computed tomography (CT) from 2002 to 2005 (n = 1315). After excluding heavy alcohol use (n = 211) and missing covariates (n = 117), the final sample included 987 participants. For the incident CKD analysis, we excluded 73 participants with prevalent CKD. Liver fat was measured by the average liver attenuation on CT. Estimated glomerular filtration rate (eGFR) was obtained using the CKD Epidemiology Collaboration Creatinine-Cystatin C equation, and CKD was defined as eGFR < 60 ml/min/1.73 m² . Microalbuminuria was defined by sex-specific urinary albumin-creatinine ratio cut-offs. Multivariable-adjusted regression models were performed to determine the association between liver fat and CKD.

RESULTS

The prevalence of hepatic steatosis and CKD were 19% and 14% respectively (55.9% women, mean age 60 ± 9 years). After adjusting for covariates, we observed no significant associations between liver fat and CKD, microalbuminuria or eGFR in cross-sectional analyses. We observed positive associations between liver fat, incident microalbuminuria and reduced eGFR in age- and sex-adjusted models; these relationships were not significant in multivariable-adjusted models.

CONCLUSIONS

In this community-based cohort study, we did not observe significant associations between liver fat and prevalent or incident CKD with a median follow-up time of 12.5 years. The association between NAFLD and CKD may be accounted for by shared risk factors; confirmatory studies are needed.

Fatty liver index (FLI) and prediction of new cases of non-alcoholic fatty liver disease: A population-based study of northern Iran

BACKGROUND AND AIMS

Non-alcoholic fatty liver disease is considered a major public health concern. The prediction of individuals who can acquire this disease would be valuable. The fatty liver index (FLI) is a non-invasive approach that has shown a good capability for discriminating individuals with non-alcoholic fatty liver disease (NAFLD) from those without it. Thus, this study evaluated the ability of the FLI to predict new cases of NAFLD following a 7-year follow up.

MATERIALS AND METHODS

This study was based on the results of follow-up on individuals who did not have NAFLD in 2009-2010, but acquired the disease by 2016-2017. A total of 2241 people who did not have NAFLD in 2009-2010 were evaluated 7 years later by ultrasound so as to diagnose new cases of NAFLD. The FLI was calculated based on data from phase 1 (performed in 2009-2010) of the cohort study. ROC analyses were performed to estimate the predictive ability of the FLI in the diagnosis of new cases of NAFLD. Logistic regression analysis was performed, in which the FLI was considered the predictor and new cases of NAFLD was the outcome.

RESULTS

The related AUCs for the FLI in men and women were 0.712 (95% CI = 0.675-0.749) and 0.721 (95% CI = 0.683-0.759), respectively. Based on the current findings, the FLI showed a significant association with NAFLD in multiple logistic regression analyses in both men and women (OR (95% CI) = 1.038 (1.029-1.047), p-value <0.001 in men and OR (95% CI) = 1.032 (1.023-1.041), p-value <0.001 in women in multiple logistic analyses).

CONCLUSION

In this study, the FLI was shown to have an acceptable capability of predicting the occurrence of new cases of NAFLD.

Comparison of laboratory indices of non-alcoholic fatty liver disease for the detection of incipient kidney dysfunction

Non-alcoholic fatty liver disease (NAFLD) is closely linked to insulin resistance and related adverse health outcomes. We investigated the non-invasive index of NAFLD that has the best performance in estimating the renal manifestations of metabolic disturbances. This nation-wide, cross-sectional study included 11,836 subjects, using various non-invasive assessments comprising routinely measured clinical and laboratory variables. The subjects were native Koreans aged 20 years or older and had no diabetes, history of liver or kidney disease. All participants were divided into quintiles according to their fibrosis-4 (FIB-4) results. Participants in the highest quintile were more hypertensive and obese with greater glycemic exposure, poor lipid profiles, and impaired kidney function, than those in the other quintiles. Multiple logistic regression, adjusted for age, sex, smoking, systolic blood pressure, white blood cell, platelet, fasting plasma glucose, and triglyceride, demonstrated that FIB-4, the hepatic steatosis index, the aspartate aminotransferase/alanine aminotransferase (AST/ALT) ratio, Gholam’s model for non-alcoholic steatohepatitis, and the BARD score were independently associated with kidney dysfunction. ROC curve analysis revealed that FIB-4 (AUC = 0.6227, 95% CI [0.5929–0.6526], p = 0.0258) was the most precise in predicting kidney dysfunction. Our findings suggest that FIB-4 may be a favorable screening tool for the renal manifestation of hepatic metabolic disturbances.

Renal dysfunction in patients with nonalcoholic fatty liver disease and risk factors

AIM

To assess the renal function in patients with nonalcoholic fatty liver disease (NAFLD) and to identify the risk factors for renal dysfunction.

METHODS

A total of 856 volunteers who underwent health examination were initially enrolled in this study to identify those with NAFLD. The biochemical indexes of patients with NAFLD and healthy volunteers were statistically analyzed, and the renal function with estimated glomerular filtration rate was calculated. In addition, the risk factors for renal damage were identified.

RESULTS

A total of 253 patients with NAFLD were identified, and the remaining 603 cases were used as a control group. There was no significant difference in serum BUN between the two groups (t = 1.678, P = 0.062), while other biochemical indexes differed significantly (P < 0.05). The prevalence of renal function impairment was higher in individuals with NAFLD compared to those without (28.8% vs 17.5%, P < 0.0001). Logistic regression analysis showed that NAFLD was associated with renal function impairment, even after adjustment for demographics and components of metabolic syndrome (OR = 2.85, 95%CI: 1.93-4.21, P = 0.000).

CONCLUSION

The biochemical indexes of NAFLD patients are significantly abnormal, and renal function impairment is associated with NAFLD. Patients with NAFLD should be regularly assessed for renal function to avoid progressing into chronic kidney disease and increasing the medical burden.

Nonalcoholic fatty liver disease increases risk of incident chronic kidney disease: A systematic review and meta-analysis

BACKGROUND

Recent studies examined the prognostic impact of nonalcoholic fatty liver disease (NAFLD) on the risk of incident chronic kidney disease (CKD). However, the extent to which NAFLD may confer risk of incident CKD is uncertain. We performed a meta-analysis of relevant studies to quantify the magnitude of the association between NAFLD and risk of incident CKD.

METHODS

We searched PubMed, Scopus and Web of Science from January 1, 2000 to August 31, 2017 using pre-defined keywords to identify large observational cohort studies with a follow-up duration of at least 1year, in which NAFLD was diagnosed by biochemistry, fatty liver index or ultrasonography. No studies with biopsy-proven NAFLD were available for the analysis. Data from selected studies were extracted, and meta-analysis was performed using random-effects modeling.

RESULTS

A total of 9 observational studies with 96,595 adult individuals (34.1% with NAFLD) of predominantly Asian descent, and 4653 cases of incident CKD stage ≥3 (i.e., defined as occurrence of estimated glomerular filtration rate<60ml/min/1.73m², with or without accompanying overt proteinuria) over a median period of 5.2years were included in the final analysis. Patients with NAFLD had a significantly higher risk of incident CKD than those without NAFLD (random-effects hazard ratio [HR] 1.37, 95% CI 1.20-1.53; I²=33.5%). Patients with more 'severe' NAFLD (according to ultrasonography and non-invasive fibrosis markers) were also more likely to develop incident CKD (n=2 studies; random-effects HR 1.50, 95% CI 1.25-1.74; I²=0%); this risk appeared to be even greater among those with ultrasound-diagnosed NAFLD and a high-intermediate NAFLD fibrosis score (n=1 study; random-effects HR 1.59, 95% CI 1.31-1.93). Sensitivity analyses did not alter these findings. Funnel plot and Egger's test did not reveal significant publication bias.

CONCLUSIONS

This largest and most updated meta-analysis to date shows that NAFLD (detected by biochemistry, fatty liver index or ultrasonography) is associated with a nearly 40% increase in the long-term risk of incident CKD. However, the observational nature of the eligible studies does not allow for proving causality. Our findings pave the way for future large, prospective, histologically-based studies.