Comparison between non-alcoholic fatty liver disease screening guidelines in children and adolescents

Ultrasound screening of paediatric non-alcoholic fatty liver disease (NAFLD): A critical literature review

INTRODUCTION

Paediatric NAFLD is an increasing global health concern, which can be effectively managed with early detection. Screening, using accurate, affordable, and accessible tests is recommended, however, there is currently no consensus on the most appropriate tests. Although ultrasound techniques are widely used, their performance against reference tests have not been fully assessed.

METHODS

A literature search of related databases for peer-reviewed original articles published from January 2010-March 2024 was conducted. Appropriate tools were used to systematise and document the search results and selected studies were quality assessed and critically appraised. Extracted data was subjected to thematic analysis and narrative synthesis.

RESULTS

Eighteen articles met the inclusion criteria. B-mode and Quantitative ultrasound techniques were compared against MR spectroscopy, MRI-PDFF and Liver biopsy.

CONCLUSION

Liver echogenicity and Steato-scores were the B-mode methods used. The former was less effective, with a maximum reported sensitivity of 70%. The latter reached up to 100% sensitivity, and >80% specificity. Ultrasound performed better with moderate-severe steatosis. There was not enough evidence to support steatosis grading, possibly due to small sample sizes and lack of established cut-off values. QUS (Quantitative Ultrasound)) methods including Continuous Attenuation Parameter (CAP), Attenuation Coefficient (AC), Ultrasound derived fat fraction (UDFF), Tissue Scatter Imaging (TSI) Hepato-Renal Index (HRI), Heterogeneity Index (HIA), Computer Assisted Ultrasound (CAUS) and Picture Archiving and Communication System (PACS-based Image analysis performed better than B-mode methods. Although QUS demonstrated excellent performance, with sensitivity and specificity of up to 100%, this will require further verification before implementation in practice.

PRACTICE IMPLICATIONS

Ultrasound techniques can effectively be used for paediatric NAFLD screening, especially in higher-risk subjects. The steato-scores method is currently recommendable for this, with excellent potential for the use of QUS, after cut-off values and validation requirements have been addressed.

An international multidisciplinary consensus on pediatric metabolic dysfunction-associated fatty liver disease

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is highly prevalent in children and adolescents, particularly those with obesity. NAFLD is considered a hepatic manifestation of the metabolic syndrome due to its close associations with abdominal obesity, insulin resistance, and atherogenic dyslipidemia. Experts have proposed an alternative terminology, metabolic dysfunction-associated fatty liver disease (MAFLD), to better reflect its pathophysiology. This study aimed to develop consensus statements and recommendations for pediatric MAFLD through collaboration among international experts.

METHODS

A group of 65 experts from 35 countries and six continents, including pediatricians, hepatologists, and endocrinologists, participated in a consensus development process. The process encompassed various aspects of pediatric MAFLD, including epidemiology, mechanisms, screening, and management.

FINDINGS

In round 1, we received 65 surveys from 35 countries and analyzed these results, which informed us that 73.3% of respondents agreed with 20 draft statements while 23.8% agreed somewhat. The mean percentage of agreement or somewhat agreement increased to 80.85% and 15.75%, respectively, in round 2. The final statements covered a wide range of topics related to epidemiology, pathophysiology, and strategies for screening and managing pediatric MAFLD.

CONCLUSIONS

The consensus statements and recommendations developed by an international expert panel serve to optimize clinical outcomes and improve the quality of life for children and adolescents with MAFLD. These findings emphasize the need for standardized approaches in diagnosing and treating pediatric MAFLD.

FUNDING

This work was funded by the National Natural Science Foundation of China (82070588, 82370577), the National Key R&D Program of China (2023YFA1800801), National High Level Hospital Clinical Research Funding (2022-PUMCH-C-014), the Wuxi Taihu Talent Plan (DJTD202106), and the Medical Key Discipline Program of Wuxi Health Commission (ZDXK2021007).

Evaluation of the ability of insulin resistance and lipid-related indices to predict the presence of NAFLD in obese adolescents

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) has become an important health issue in adolescents. Although several parameters and indices have been investigated for the evaluation of NAFLD in adults, these indices are limited in adolescents. In this study, body mass index, waist circumference, triponderal mass index, HbA1c, homeostatic model assessment insulin resistance (HOMA-IR), triglyceride/high-density lipoprotein (Tg/HDL), the lipid accumulation product (LAP) index, the triglyceride-glucose (TyG) index and the aminotransferase (AT) index were examined together, and their diagnostic values in the clinical treatment of NAFLD were compared.

MATERIALS AND METHODS

Seventynine adolescents (10-19 years old) with obesity who were admitted to a pediatric clinic between January and August 2022 and who were diagnosed with exogenous obesity without any comorbidities were included in the study. The presence of NAFLD was evaluated by liver magnetic resonance imaging. The laboratory findings were obtained retrospectively from system records. Parameters were compared between the NAFLD (+) and NAFLD (-) groups. Logistic regression analysis was used to determine the most effective factors for NAFLD treatment. Receiver operating characteristic (ROC) analysis was performed with significant indices. Sex, HOMA-IR, TyG and AT indices were evaluated together with multivariate analysis to design a diagnostic scale.

RESULTS

HbA1c, HOMA-IR, AT indices and TyG indices were greater in the NAFLD (+) group (P = 0.012; P = 0.001; P = 0.012; P = 0.002, respectively). There was a positive correlation between liver fat percentage and HOMA-IR, the TyG index, the AT index, and Tg/HDL. According to the regression analysis, male sex and elevated HOMA-IR were determined to be significant risk factors for the presence of NAFLD. A probability scale with 4 parameters [sex, HOMA-IR, the TyG index, and alanine aminotransferase (ALT)] was designed with 82.5% specificity and 80% sensitivity.

CONCLUSION

Evaluation of the HOMA-IR and TyG indices, especially in high-risk patients, will support the diagnosis of NAFLD via ultrasonography. A probability scale with ALT, HOMA-IR, TyG, and sex data with a diagnostic accuracy of 80% may aid in the diagnosis of NAFLD in adolescents with obesity.

Missed Opportunities in Guideline-Based Fatty Liver Screening Among 3.5 Million Children

OBJECTIVE

Determine screening rates and examine socio-demographic characteristics of metabolic dysfunction-associated steatotic liver disease (MAFLD) screening in a large population of obese children.

METHODS

We used Explorys (IBM) which contains aggregated population-level electronic health record data from approximately 360 hospitals and 317,000 providers across the United States to determine MAFLD screening rates. In children 10 to 14 years, obesity was determined based on body mass index ≥ 95%, or encounter with an international classification of disease obesity code. We determined screening rates by calculating the percentage of children with obesity who had an alanine aminotransferase tested, further analyzed by gender, race, and insurance.

RESULTS

Of 3,558,420 children, 513,170 (14.4%) were obese. Of obese children, only 9.3% were screened for MAFLD. Females were more likely screened than males (odds ratio (OR) 1.09 (95% confidence intervals (CI): 1.07-1.12)); White children were more likely screened than non-White children (OR 1.21 (95% CI: 1.18-1.23)), and children with Medicaid more likely screened than children with non-Medicaid insurance (OR 1.34 (95% CI: 1.32-1.37)).

CONCLUSIONS

The percentage of obese children receiving screening for MAFLD was low. Female gender, White race, and Medicaid insurance were associated with increased screening rates. These findings highlight the need to increase adherence to MAFLD screening. Reporting screening as a health quality measure may reduce implementation gaps in MAFLD screening.

Nonalcoholic Fatty Liver Disease and Continuous Metabolic Syndrome in Adolescents with Overweight/Obesity

INTRODUCTION

Nonalcoholic fatty liver disease is the leading cause of pediatric chronic liver disease. Although nonalcoholic fatty liver disease is closely associated with obesity, its relationship with metabolic syndrome in children is not fully understood. The main aim of this study was to evaluate the association between nonalcoholic fatty liver disease and a combination of cardiometabolic risk factors in adolescents with overweight/obesity, using a pediatric metabolic syndrome score (PsiMS) to predict metabolic syndrome.

METHODS

A retrospective cohort study was conducted. Subjects with overweight/obesity aged 10 to 17 followed at two clinical centers in Portugal (2018 - 2021) were enrolled. The independent association of nonalcoholic fatty liver disease with PsiMS, and of other potential predictors, was tested through multiple regression analyses. Receiver operator characteristic curve analysis was performed to estimate the optimal cutoff of PsiMS to discriminate metabolic syndrome.

RESULTS

Eighty-four subjects were included (median age at baseline 11.5 years). The prevalence rate of nonalcoholic fatty liver disease was 51% and the prevalence rate of metabolic syndrome was 7%. The mean PsiMS was 2.05 ± 0.48 at the first evaluation, and 2.11 ± 0.52 at the last evaluation (mean follow-up time was 15 months). The nonalcoholic fatty liver disease group had significantly (p < 0.05) higher weight and body mass index z-scores, higher rate of severe obesity and higher waist circumference percentile. PsiMS was highly accurate in predicting metabolic syndrome (area under the curve = 0.96), with an optimal cutoff of 2.46 (sensitivity 100%, specificity 89%). In the univariate analysis, no statistically significant association was observed between nonalcoholic fatty liver disease and PsiMS. In the multiple regression analysis, female sex had a negative association with PsiMS (first and last evaluation). Independent predictors of a higher PsiMS at first evaluation were: ≥ 2 metabolic syndrome criteria, body mass index z-score, insulin resistance and dyslipidemia. At the last evaluation, independent predictors of a higher PsiMS were: nonalcoholic fatty liver disease, baseline PsiMS and body mass index increase from baseline.

CONCLUSION

The results suggest a good performance of the PsiMS to assess metabolic syndrome and that nonalcoholic fatty liver disease is associated with PsiMS at follow-up.

Noninvasive scores are poorly predictive of histological fibrosis in paediatric fatty liver disease

OBJECTIVES

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in children. Roughly a quarter of paediatric patients with NAFLD develop nonalcoholic steatohepatitis and fibrosis. Here, we evaluated the diagnostic accuracy of previously published noninvasive fibrosis scores to predict liver fibrosis in a large European cohort of paediatric patients with NAFLD.

METHODS

The 457 patients with biopsy-proven NAFLD from 10 specialized centers were included. We assessed diagnostic accuracy for the prediction of any (F ≥ 1), moderate (F ≥ 2) or advanced (F ≥ 3) fibrosis for the AST/platelet ratio (APRI), Fibrosis 4 score (FIB-4), paediatric NAFLD fibrosis score (PNFS) and paediatric NAFLD fibrosis index (PNFI).

RESULTS

Patients covered the full spectrum of fibrosis (F0: n = 103; F1: n = 230; F2: n = 78; F3: n = 44; F4: n = 2). None of the scores were able to accurately distinguish the presence of any fibrosis from no fibrosis. For the detection of moderate fibrosis, area under the receiver operating characteristic curve (AUROC) were: APRI: 0.697, FIB-4: 0.663, PNFI: 0.515, PNFS: 0.665, while for detection of advanced fibrosis AUROCs were: APRI: 0.759, FIB-4: 0.611, PNFI: 0.521, PNFS: 0.712. Fibrosis scores showed no diagnostic benefit over using ALT ≤ 50/ > 50 IU/L as a cut-off.

CONCLUSIONS

Established fibrosis scores lack diagnostic accuracy to replace liver biopsy for staging of fibrosis, giving similar results as compared to using ALT alone. New diagnostic tools are needed for Noninvasive risk-stratification in paediatric NAFLD.

The body mass index increases the genetic risk scores' ability to predict risk of hepatic damage in European adolescents: The HELENA study

BACKGROUND

Hepatic disorders are often complex and multifactorial, modulated by genetic and environmental determinants. During the last years, the hepatic disease has been progressively established from early stages in life. The use of genetic risk scores (GRS) to predict the genetic susceptibility to a particular phenotype among youth has gained interest in recent years. Moreover, the alanine aminotransferase (ALT) blood biomarker is often considered as hepatic screening tool, in combination with imaging techniques. The aim of the present study was to develop an ALT-specific GRS to help in the evaluation of hepatic damage risk in European adolescents.

METHODS

A total of 972 adolescents (51.3% females), aged 12.5-17.5 years, from the Healthy Lifestyle in Europe by Nutrition in Adolescence study were included in the analyses. The sample incorporated adolescents in all body mass index (BMI) categories and was divided considering healthy/unhealthy ALT levels, using sex-specific cut-off points. From 1212 a priori ALT-related single nucleotide polymorphisms (SNPs) extracted from candidate gene selection, a first screening of 234 SNPs univariately associated was established, selecting seven significant SNPs (p < .05) in the multivariate model. An unweighted GRS (uGRS) was developed by summing the number of reference alleles, and a weighted GRS (wGRS), by multiplying each allele to its estimated coefficient.

RESULTS

The uGRS and wGRS were significantly associated with ALT (p < .001). The area under curve was obtained integrating BMI as clinical factor, improving the predictive ability for uGRS (.7039) and wGRS (.7035), using 10-fold internal cross-validation.

CONCLUSIONS

Considering BMI status, both GRSs could contribute as complementary tools to help in the early diagnosis of hepatic damage risk in European adolescents.

Analysis of risk factors for non-alcoholic fatty liver disease in hospitalized children with obesity before the late puberty stage

Objective

This study aimed to determine the clinical characteristics of obese pediatric non-alcoholic fatty liver disease (NAFLD) in central China and verify the applicability of some known risk factors for pediatric NAFLD before late puberty.

Methods

This was a retrospective case-control study. A total of 1,029 inpatients at Wuhan Children's Hospital before the late puberty stage were enrolled in the study, including 815 children with obesity (non-NAFLD group) and 214 children with obesity and NAFLD (NAFLD group) diagnosed by liver ultrasound. Subgroup analyses were performed according to sex and puberty. The anthropometric indices and laboratory test data of these 1,029 children were sorted. After intergroup comparison, a logistic regression model was used to determine the risk factors for pediatric NAFLD. Significant risk factors for NAFLD were further tested using receiver operating characteristic (ROC) curves to evaluate their ability to predict an early diagnosis of NAFLD.

Results

The NAFLD group had a mean age of 11.03 ± 1.66, with 11.18 ± 1.66 and 10.27 ± 1.45 years for male and female children, respectively (p < 0.05 and p < 0.01, respectively). Even subdivided by both sex and puberty, raised body mass index (BMI), homeostatic model-insulin resistance, triglycerides, alanine transaminase (ALT), aspartate aminotransferase (AST), and gamma-glutamyl transferase (γ-GT) were still found in the non-NAFLD and NAFLD groups (p < 0.05 and p < 0.01, respectively). The results of logistic regression analysis showed that BMI (odds ratio [OR], 1.468;95% confidence interval [CI], 1.356-1.590; p<0.001) and ALT (OR, 1.073;95%CI, 1.060-1.087; P<0.001) were two most independent risk factors for NAFLD. The maximal OR for BMI was 1.721 (95% CI, 1.336-2.217). In the female group, the maximal OR of ALT was found to be 1.104 (95% CI, 1.061-1.148). Age and thyroid-stimulating hormone (TSH) and γ-GT levels were also risk factors, but they appeared only in some groups. The results of the ROC analysis showed that ALT was a better predictor of pediatric NAFLD than BMI. The maximum area under the ROC curve in six of the nine groups belongs to ALT.

Conclusions

BMI, ALT, and age are risk factors for NAFLD in children with obesity before late puberty. BMI had the greatest exposure risk for NAFLD, and ALT had the highest predictive value for the diagnosis of NAFLD. At the stratified level, for exposure risk, age was specific to the male sex, TSH was specific to the early puberty stage, and γ-GT was specific to the female sex plus the prepuberty stage. On a stratified level, for the female sex, even with age stratification, BMI rather than ALT has a better ability for the diagnosis of NAFLD.

Prevalence of nonalcoholic fatty liver disease increased with type 2 diabetes mellitus in overweight/obese youth with polycystic ovary syndrome

OBJECTIVES

Polycystic ovary syndrome (PCOS) increases non-alcoholic fatty liver disease (NAFLD) risk and severity in adults, but data in adolescents with diverse backgrounds are limited. We evaluated NAFLD prevalence and characterized NAFLD risk factors in overweight/obese adolescents by PCOS status.

METHODS

Retrospective study of overweight (n=52)/obese (n=271) female adolescents (12-18 years old), evaluated clinically 2012-2020, was conducted comparing PCOS patients to age-matched non-PCOS controls. NAFLD was defined as ALT≥44U/L x2 and/or ≥80U/L x1, hepatic steatosis on imaging, or NAFLD on biopsy, in absence of other liver disease. Metabolic comorbidities were captured. Log-binomial regression models estimated prevalence risk ratios (PR).

RESULTS

NAFLD prevalence was 19.1 % in adolescents with PCOS (n=161), similar to those without (n=162) (16.8 %, p=0.6). Adolescents with PCOS were more likely to have insulin resistance, hypercholesterolemia, and higher triglycerides (p<0.05). Those with PCOS and concomitant type 2 diabetes (T2DM) did have increased NAFLD risk (PR 2.5, p=0.04), but those with PCOS without T2DM did not (PR 0.9, p=0.8). Adolescents with PCOS and NAFLD, compared to those with PCOS without NAFLD, had a higher prevalence of metabolic comorbidities including hypercholesterolemia (77 vs. 48 %), T2DM (29 vs. 8 %), and hypertriglyceridemia (65 vs. 37 %) (p<0.01).

CONCLUSIONS

Almost 1 in 5 overweight/obese female adolescents had NAFLD, but PCOS did not increase NAFLD risk in this diverse cohort. Among young women with PCOS, concomitant T2DM did increase the risk for NAFLD. Closer monitoring of obesity comorbidities in adolescents with PCOS is essential for optimizing health and merits updating current guidelines.

Updated upper limits of normal serum alanine aminotrasferase levels for screening metabolic dysfunction-associated fatty liver disease in obese children

BACKGROUND/PURPOSE

Alanine aminotransferase (ALT) is a cost-effective screening test for asymptomatic liver diseases. The aims of this study are to redefine the ULNs of ALT using the 2010-2012 Nutrition and Health Survey in Taiwan (NAHSIT) database and to determine whether the updated ULNs can better screen for metabolic dysfunction-associated fatty liver disease (MAFLD) in obese children.

METHODS

Reference data were obtained from 2895 NAHSIT participants (1442 boys, 1453 girls) aged 6-18 years. Participants with any of MAFLD-related metabolic risk factors, including overweight/obesity, elevated triglyceride, low high-density lipoprotein cholesterol and high fasting glucose, were excluded. This study compared the sensitivities of different ULNs of ALT for detecting MAFLD in our previously established cohort of obese children.

RESULTS

The ULNs of ALT defined as the 95th percentile in metabolically healthy NAHSIT participants were 23 IU/L for boys and 18 IU/L for girls. When using the updated ULNs, the percentages of elevated ALT levels were 13.0% in boys and 7.8% in girls of all NAHSIT participants. When using the updated ULNs of ALT to detect MAFLD in obese children, the sensitivity was 84.0% in boys and 74.3% in girls. In contrast, when using the conventional ALT cutoff (>40 IU/L), the sensitivity decreased to 61.4% in boys and 36.4% in girls.

CONCLUSION

After taking into account MAFLD-related metabolic risk factors, the ULNs of ALT are 23 IU/L for boys and 18 IU/L for girls in Taiwan. The updated ULNs may be better cutoffs for screening MAFLD in obese children.

Nonalcoholic Steatohepatitis in Children

Nonalcoholic fatty liver disease (NAFLD) is the leading cause of chronic liver disease in children. Although environmental factors are major contributors to early onset, children have both shared and unique genetic risk alleles as compared with adults with NAFLD. Treatment relies on reducing environmental risk factors, but many children have persistent diseases. No medications are approved specifically for the treatment of NAFLD, but some anti-obesity or diabetes treatments may be beneficial. Pediatric NAFLD increases the risk of diabetes and other cardiovascular risk factors. Long-term prospective studies are needed to determine the long-term risk of hepatic and non-hepatic morbidity and mortality in adulthood.

Non-Invasive Diagnostic Test for Advanced Fibrosis in Adolescents With Non-Alcoholic Fatty Liver Disease

INTRODUCTION

Non-alcoholic fatty liver disease (NAFLD) is a multifaceted disease that includes a wide spectrum of liver damage. The presence and the degree of fibrosis are considered important factors for the prognosis of NAFLD and in predicting the risk of developing cirrhosis. Our aim was to evaluate the usefulness of four fibrosis scores (aspartate aminotransferase/Platelet Index [APRI], FIB-4, NAFLD Fibrosis Score [NFS], and Hepamet) in predicting different degrees of fibrosis among children with biopsy-proven NAFLD.

METHODS

About 286 adolescents [mean age 14.3 years ± 2.5; 154 (53.6%) males], referred between January 2014 and December 2019, with biopsy-proven NAFLD were enrolled.

RESULTS

About 173 (60.4%) patients presented fibrosis at histological analysis. In particular: 140 (49.3%) patients had F = 1, 31 (10.8%), had F = 2 and 2 (0.66%) had F = 3. APRI (AUROC 0.619, 95% CI 0.556-0.679) and Hepamet (AUROC 0.778, 95% CI 0.722-0.828) scores had significant (p < 0.001) accuracy to distinguish subjects with fibrosis; while NFS and FIB-4 had not. APRI had a positive predictive value (PPV) of 62.77% (95% CI 57.96-67.35) and an negative predictive value (NPV) of 52.01% (95% CI 46.54-57.43); Hepamet a PPV of 63.24% (95% CI 59.95-66.41) and an NPV of 61.29% (52.9-69.01).

CONCLUSIONS

Our study showed that Hepamet and APRI perform better than NFS and FIB-4 for identifying fibrosis in patients with NAFLD, but do not have PPVs so high to be considered diagnostic. Therefore, they cannot be employed, in children, for a certain diagnosis of fibrosis or its progression and cannot replace liver biopsy as the gold diagnostic standard. It is, therefore, necessary to continue to research and develop new markers of exclusive fibrosis.

Possible Hepatoprotective Effect of Tocotrienol-Rich Fraction Vitamin E in Non-alcoholic Fatty Liver Disease in Obese Children and Adolescents

Obesity has become a worldwide health concern among the pediatric population. The prevalence of non-alcoholic fatty liver disease (NAFLD) is growing rapidly, alongside the high prevalence of obesity. NAFLD refers to a multifactorial disorder that includes simple steatosis to non-alcoholic steatohepatitis (NASH) with or devoid of fibrosis. NAFLD is regarded as a systemic disorder that influences glucose, lipid, and energy metabolism with hepatic manifestations. A sedentary lifestyle and poor choice of food remain the major contributors to the disease. Prompt and timely diagnosis of NAFLD among overweight children is crucial to prevent the progression of the condition. Yet, there has been no approved pharmacological treatment for NAFLD in adults or children. As indicated by clinical evidence, lifestyle modification plays a vital role as a primary form of therapy for managing and treating NAFLD. Emphasis is on the significance of caloric restriction, particularly macronutrients (fats, carbohydrates, and proteins) in altering the disease consequences. A growing number of studies are now focusing on establishing a link between vitamins and NAFLD. Different types of vitamin supplements have been shown to be effective in treating NAFLD. In this review, we elaborate on the potential role of vitamin E with a high content of tocotrienol as a therapeutic alternative in treating NAFLD in obese children.

Nonalcoholic Fatty Liver Disease and Estimated Insulin Resistance in Obese Youth: A Mendelian Randomization Analysis

CONTEXT

Nonalcoholic fatty liver disease (NAFLD) is associated with insulin resistance (IR) and predicts type 2 diabetes. Currently, it is uncertain whether NAFLD may directly cause IR or vice versa.

OBJECTIVE

To test the hypothesis that NAFLD is causally related to IR.

DESIGN AND METHODS

We performed a Mendelian randomization (MR) in 904 obese children/adolescents using an NAFLD-related genetic risk score (GRS) as an instrumental variable. We assessed NAFLD by ultrasonography and IR by homeostasis model assessment (HOMA-IR). We also interrogated the MAGIC Consortium dataset of 46 186 adults to assess the association between PNPLA3 rs738409 (ie, the most robust NAFLD-related polymorphism) and HOMA-IR, and we performed a 2-sample MR with 2 large datasets to test reverse causation (HOMA-IR increasing the risk of NAFLD).

RESULTS

Nonalcoholic fatty liver disease prevalence increased by 20% for every increase in the GRS (β-coefficient = 0.20, P < 0.001), and NAFLD was associated with ln-HOMA-IR (β-coefficient = 0.28, P < 0.001). Thus, the expected increase in ln-HOMA-IR for every increase in the GRS (expected β-coefficient) was 0.056 (0.28*0.20) in the case of complete NAFLD-HOMA-IR causal association, and 0.042 in the case of 75% causality. In our cohort, the GRS did not predict ln-HOMA-IR (β-coefficient = 0.007, P = 0.75). In the MAGIC cohort, the PNPLA3 rs738409 did not associate with ln-HOMA-IR. The 2-sample MR failed to show a causal association between ln-HOMA-IR and NAFLD.

CONCLUSIONS

Our study shows that genetically-influenced NAFLD does not increase HOMA-IR, and genetically-influenced HOMA-IR does not increase the risk of NAFLD. Shared pathogenic pathways or NAFLD subtypes not "captured" by our MR design might underpin the association between NAFLD and HOMA-IR.

Noninvasive diagnostic tools for pediatric NAFLD: where are we now?

INTRODUCTION

Nonalcoholic fatty liver disease (NAFLD) is a leading cause of liver disease in the pediatric population. It is a significant liver complication of obesity that also prominently affects children. Over the past decade, several noninvasive methods have been investigated for replacing liver biopsy to identify which children with NAFLD have nonalcoholic steatohepatitis (NASH) and fibrosis. These methods that aim to differentiate the type and extent of liver damage are based on two main different methodologies: a 'biological' approach centered on the quantification of circulating biomarkers; and a 'physical' approach established by analyzing different imaging data.

AREAS COVERED

In this review, we illustrate the state of the art and recent discoveries on noninvasive methods for the diagnosis of NAFLD, NASH, and advanced fibrosis.

EXPERT OPINION

Currently, noninvasive tests cannot diagnose NASH or determine the degree of fibrosis. However, several lines of evidence have suggested that if these tests are used in a complementary way with other laboratory tests and imaging they have the potential to be used to monitor progression of disease and response to therapy in pediatric NAFLD. Future scientific research will focus on combining these methods with multiple potential predictors of genetic susceptibility.

Effects of Dietary and Lifestyle Interventions on Liver, Clinical and Metabolic Parameters in Children and Adolescents with Non-Alcoholic Fatty Liver Disease: A Systematic Review

Non-alcoholic fatty liver disease (NAFLD) affects 5.5–10.3% of children worldwide, while in obese individuals, it increases to almost 34%. Pediatric NAFLD is consistently associated with metabolic syndrome and insulin resistance. As no pharmacological agents exist for the treatment of NAFLD, lifestyle modifications remain the only therapy. However, as not all overweight/obese children have NAFLD, high-quality data, focused exclusively on NAFLD population are needed. Therefore, the present systematic review assessed the efficacy of lifestyle (diet or exercise) based on randomized controlled clinical trials (RCTs) on liver, anthropometric, glucose, and lipid parameters in children, with imaging or biopsy-proven NAFLD. In general, the results were inconclusive and therefore no specific recommendations could be drawn. In most studies, differences were derived from within group comparisons, which are known to be highly misleading. However, both low-carbohydrate and low-fat diets could benefit liver outcomes, as long as weight loss is achieved, but not necessary glucose and lipid parameters. No RCTs were found on exercise alone, as compared to no intervention on pediatric NAFLD. Concerning diet plus exercise interventions, all studies led to improvements in liver outcomes accompanied with weight loss. Resolution of NAFLD was found in considerably high percentages, while improvements were also seen in glucose but were modest in lipid parameters.

Nonalcoholic Fatty Liver Disease Is Associated With Low Skeletal Muscle Mass in Overweight/Obese Youths

Background: Recent studies in adult non-elderly and elderly individuals have reported a link between nonalcoholic fatty liver disease (NAFLD) and sarcopenia. Nonetheless, whether this relationship would be found outside these populations it is still unknown. Hence, we evaluated the relationship between NAFLD and skeletal muscle mass in children and adolescents with overweight/obesity. Methods: Two-hundred and thirty-four overweight/obese youths were enrolled. NAFLD was diagnosed by ultrasononography, after exclusion of infectious and metabolic disorders. Forty of the patients with NAFLD had also liver biopsy. Total and regional lean body mass and total fat mass measurements were obtained by dual-energy X-ray absorptiometry. The relative muscle mass (RMM) was defined as the percent of muscle mass (kg) relative to the sum of muscle and fat (kg) mass. Appendicular skeletal muscle mass (ASM) was calculated by the sum of muscle masses of the four limbs (kg), and expressed as percent of body weight. Results: Subjects were stratified according to tertiles of RMM. The prevalence of abdominal obesity, dyslipidemia, insulin resistance, metabolic syndrome, NAFLD as well as biopsy-proven nonalcoholic steatohepatitis (NASH) was significantly increased in the lowest tertile of RMM. After controlling for age, sex and Tanner stage, children in the lowest tertile of RMM had an increased risk for NAFLD (OR= 2.80, 95% CI=1.57-5.02) compared to those in the other two tertiles. This association persisted after additional adjustments for clinical and metabolic variables. Similarly, the risk of NAFLD in the lowest tertile of ASM/weight index was significantly higher compared to those in the other two tertiles after adjustment for the above confounders. Conclusions: This is the first study to establish an independent association between low muscle mass and NAFLD/NASH in overweight/obese youths. Considering the worldwide increase of pediatric obesity, measurements of muscle mass may serve as useful method of identifying among obese children those at high metabolic risk who may need intensive lifestyle interventions to prevent NAFLD and its progression.