acNASH index to diagnose nonalcoholic steatohepatitis: a prospective derivation and global validation study

Diagnostic accuracy of exhaled nitric oxide for the non-invasive identification of patients with fibrotic metabolic dysfunction-associated steatohepatitis

BACKGROUND

Fibrotic metabolic dysfunction-associated steatohepatitis (MASH) is a condition at risk of progressing to advanced liver disease. We examined whether an innovative exhaled nitric oxide (eNO) breath test (BT) can accurately diagnose fibrotic MASH without requiring blood tests.

METHODS

One hundred and forty-seven patients with MASH were recruited, and all tests were undertaken within 1 week of recruitment. With fibrotic MASH (NAS ≥ 4 and fibrosis stage ≥ 2) as the main outcome indicator, the diagnostic efficacy of eNO in identifying fibrotic MASH was compared to other validated models for advanced fibrosis requiring venesection, namely FAST, Agile 3+, and FIB-4 scores.

RESULTS

The mean age was 40.36 ± 12.28 years, 73.5% were men. Mean body mass index was 28.83 ± 4.31 kg/m2. The proportion of fibrotic MASH was 29.25%. The area under the receiver operating curve for eNO in diagnosing fibrotic MASH was 0.737 [95% CI 0.650-0.823], which was comparable to FAST (0.751 [0.656-0.846]), Agile 3+ (0.764 [0.670-0.858]), and FIB-4 (0.721 [0.620-0.821]) (all DeLong test p > 0.05). A cut-off of eNO <8.5 ppb gave a sensitivity of 86.0% and a negative predictive value of 88.5% for ruling-out fibrotic MASH. A cut-off of eNO >13.5 ppb provided a specificity of 91.3% and a positive predictive value of 65.4% for ruling-in fibrotic MASH. Sensitivity analyses demonstrated that the diagnostic efficacy of eNO was similar across characteristics such as age. Moreover, adding vibration-controlled transient elastography-LSM (liver stiffness measurement) reduced the uncertainty interval from 46.9% to 39.5%.

CONCLUSIONS

The eNO-BT is a promising simple test for non-invasively identifying fibrotic MASH, and its performance is further improved by adding LSM measurement.

Diagnosis and non-invasive assessment of MASLD in type 2 diabetes and obesity

BACKGROUND

Metabolic dysfunction-associated steatotic liver disease (MASLD) is currently the most common chronic liver disease and an important cause of cirrhosis and hepatocellular carcinoma. It is strongly associated with type 2 diabetes and obesity. Because of the huge number of patients at risk of MASLD, it is imperative to use non-invasive tests appropriately.

AIMS

To provide a narrative review on the performance and limitations of non-invasive tests, with a special emphasis on the impact of diabetes and obesity.

METHODS

We searched PubMed and Cochrane databases for articles published from 1990 to August 2023.

RESULTS

Abdominal ultrasonography remains the primary method to diagnose hepatic steatosis, while magnetic resonance imaging proton density fat fraction is currently the gold standard to quantify steatosis. Simple fibrosis scores such as the Fibrosis-4 index are well suited as initial assessment in primary care and non-hepatology settings to rule out advanced fibrosis and future risk of liver-related complications. However, because of its low positive predictive value, an abnormal test should be followed by specific blood (e.g. Enhanced Liver Fibrosis score) or imaging biomarkers (e.g. vibration-controlled transient elastography and magnetic resonance elastography) of fibrosis. Some non-invasive tests of fibrosis appear to be less accurate in patients with diabetes. Obesity also affects the performance of abdominal ultrasonography and transient elastography, whereas magnetic resonance imaging may not be feasible in some patients with severe obesity.

CONCLUSIONS

This article highlights issues surrounding the clinical application of non-invasive tests for MASLD in patients with type 2 diabetes and obesity.

Non-invasive diagnosis of non-alcoholic fatty liver disease: Current status and future perspective

Non-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease throughout the world. Hepatocellular carcinoma (HCC) and liver cirrhosis can result from nonalcoholic steatohepatitis (NASH), the severe stage of NAFLD progression. By some estimates, NAFLD affects almost one-third of the world's population, which is completely new and serious public health issue. Unfortunately, NAFLD is diagnosed by exclusion, and the gold standard for identifying NAFLD/NASH and reliably measuring liver fibrosis remains liver biopsy, which is an invasive, costly, time-consuming procedure and involves variable inter-observer diagnosis. With the progress of omics and imaging techniques, numerous non-invasive serological assays have been generated and developed. On the basis of these developments, non-invasive biomarkers and imaging techniques have been combined to increase diagnostic accuracy. This review provides information for the diagnosis and assessment of NAFLD/NASH in clinical practice going forward and may assist the clinician in making an early and accurate diagnosis and in proposing a cost-effective patient surveillance. We discuss newly identified and validated non-invasive diagnostic methods from biopsy-confirmed NAFLD patient studies and their implementation in clinical practice, encompassing NAFLD/NASH diagnosis and differentiation, fibrosis assessment, and disease progression monitoring. A series of tests, including 20-carboxy arachidonic acid (20-COOH AA) and 13,14-dihydro-15-keto prostaglandin D2 (dhk PGD2), were found to be potentially the most accurate non-invasive tests for diagnosing NAFLD. Additionally, the Three-dimensional magnetic resonance imaging (3D-MRE), combination of the FM-fibro index and Liver stiffness measurement (FM-fibro LSM index) and the machine learning algorithm (MLA) tests are more accurate than other tests in assessing liver fibrosis. However, it is essential to use bigger cohort studies to corroborate a number of non-invasive diagnostic tests with extremely elevated diagnostic values.

Non-invasive tools for liver steatosis and steatohepatitis predict incidence of diabetes, cardiovascular disease and mortality 20 years later: The ATTICA cohort study (2002-2022)

BACKGROUND & AIMS

Non-alcoholic fatty liver disease (NAFLD) or, as recently renamed, metabolic dysfunction-associated steatotic liver disease (MASLD), has common metabolic pathways with diabetes and cardiovascular disease (CVD). Non-invasive tools (NITs) for liver steatosis and steatohepatitis (MASH) were studied as potential predictors of diabetes, cardiovascular disease (CVD) and mortality over a 20-year period.

METHODS

In 2001-02, 3042 individuals from the Attica region of Greece were recruited randomly, and were stratified by subgroups of sex, age and region to reflect the general urban population in Athens, Greece. Validated NITs for hepatic steatosis (Hepatic Steatosis Index (HIS), Fatty Liver Index (FLI), Lipid Accumulation Product (LAP), NAFLD liver fat score (NAFLD-LFS)) and steatohepatitis (Index of non-alcoholic steatohepatitis (ION), aminotransferase-creatinine-clearance non-alcoholic steatohepatitis (acNASH)) were calculated. Incidence of diabetes, CVD and mortality were recorded 5, 10 and 20 years later.

RESULTS

Within a 20-year observation period, the diabetes and CVD incidence was 26.3% and 36.1%, respectively. All hepatic steatosis and steatohepatitis NITs were independently associated with diabetes incidence. ION and acNASH presented independent association with CVD incidence [(Hazard Ratio (HR)per 1 standard deviation (SD) = 1.33, 95% Confidence Interval (95% CI) (1.07, 1.99)) and (HRper 1 SD = 1.77, 95% CI (1.05, 2.59)), respectively]. NAFLD-LFS which is a steatosis NIT indicating features of steatohepatitis, was linked with increased CVD mortality (HRper 1 SD = 1.35, 95% CI (1.00, 2.30)) and all-cause mortality (HRper 1 SD = 1.43, 95% CI (1.08, 2.01)). Overall, steatohepatitis NITs (i.e., ION and acNASH) presented stronger associations with the outcomes of interest compared with steatosis NITs. Clinically important trends were observed in relation to diabetes and CVD incidence progressively over time, i.e. 5, 10 and 20 years after baseline.

CONCLUSIONS

Easily applicable and low-cost NITs representing steatohepatitis may be early predictors of diabetes and CVD onset. More importantly, these NITs increased the attributable risk conveyed by conventional CVD risk factors by 10%. Thus, their potential inclusion in clinical practice and guidelines should be studied further.

A Novel Score Based on Controlled Attenuation Parameter Accurately Predicts Hepatic Steatosis in Individuals With Metabolic Dysfunction Associated Steatotic Liver Disease: A Derivation and Independent Validation Study

INTRODUCTION

In metabolic dysfunction-associated steatotic liver disease, the diagnostic efficacy of controlled attenuation parameter (CAP) was not very accurate in evaluating liver fat content. The aim of this study was to develop a score, based on CAP and conventional clinical parameters, to improve the diagnostic performance of CAP regarding liver fat content.

METHODS

A total of 373 participants from 2 independent Chinese cohorts were included and divided into derivation (n = 191), internal validation (n = 75), and external validation (n = 107) cohorts. Based on the significant difference index between the 2 groups defined by the magnetic resonance imaging-proton density fat fraction (MRI-PDFF) in derivation cohort, the optimal model (CAP-BMI-AST score [CBST]) was screened by the number of parameters and the area under the receiver operating characteristic curve (AUROC). In the internal and external validation cohorts, the AUROC and corresponding 95% confidence intervals (CIs) were used to compare the diagnostic performance of CBST with that of CAP.

RESULTS

We constructed the CBST = -14.27962 + 0.05431 × CAP - 0.14266 × body mass index + 0.01715 × aspartate aminotransferase. When MRI-PDFF was ≥20%, ≥10%, and ≥5%, the AUROC for CBST was 0.77 (95% CI 0.70-0.83), 0.89 (95% CI 0.83-0.94), and 0.93 (95% CI 0.88-0.98), which was higher than that for CAP respectively. In the internal validation cohort, the AUROC for CBST was 0.80 (95% CI 0.70-0.90), 0.95 (95% CI 0.91-1.00), and 0.98 (95% CI 0.94-1.00). The optimal thresholds of CBST were -0.5345, -1.7404, and -1.9959 for detecting MRI-PDFF ≥20%, ≥10%, and ≥5%, respectively.

DISCUSSION

The CBST score can accurately evaluate liver steatosis and is superior to the CAP.

Problems and Challenges Associated with Renaming Non-alcoholic Fatty Liver Disease to Metabolic Associated Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) has become the world’s largest chronic liver disease in the 21st century, affecting 20%–30% of the world’s population. As the epidemiology, etiology, and pathogenesis of NAFLD have been studied in-depth, it has been gradually recognized that most patients with NAFLD have one or more combined metabolic abnormalities known as metabolic syndrome. In 2020, the international expert group changed the name of NAFLD to metabolic-associated fatty liver disease (MAFLD) and proposed new diagnostic criteria for MAFLD and MAFLD-related liver cirrhosis, as well as the conceptual framework of other cause-related fatty liver diseases to avoid diagnosis based on the exclusion of other causes and better reflect its pathogenesis. However, there are still many ambiguities in the term, and changing the name does not address the unmet key needs in the field. The change from NAFLD to MAFLD was not just a change of definition. The problems and challenges are summarized as follows: epidemiology, children, rationality of “metabolism,” diagnostic criteria, double/multiple causes, drug discovery, clinical trials, and awareness raising. Metabolic-associated fatty liver disease has complex disease characteristics, and there are still some problems that need to be solved.

Leucine aminopeptidase 3:a promising serum biomarker candidate for nonalcoholic steatohepatitis diagnosis

BACKGROUND & AIMS

Nonalcoholic steatohepatitis (NASH) is a highly prevalent liver disease that lacks targeted therapeutic drugs and non-invasive diagnostic methods. Increasing evidence demonstrated that aberrant expression of leucine aminopeptidase 3 (LAP3) is involved in NASH. Herein, we aimed to investigate whether LAP3 can be a promising serum biomarker for NASH diagnosis.

METHODS

Liver tissues and serum from NASH rats, serum from NASH patients, and liver biopsies from chronic hepatitis B (CHB) patients combined with NASH (CHB+NASH) were obtained to evaluate the LAP3 level. Correlation analysis was conducted to evaluate the association between LAP3 expression and clinical indexes in CHB patients and CHB+NASH patients. ROC curve analysis of LAP3 in the serum and liver was applied to assess whether LAP3 can be a promising biomarker for NASH diagnosis.

RESULTS

LAP3 was significantly upregulated in serum and hepatocytes of NASH rats and patients with NASH. Correlation analysis revealed that LAP3 in the liver of CHB patients and CHB+NASH patients showed a strong positive correlation with lipidome indicators total cholesterol (TC) and triglyceride (TG), and liver fibrosis indicator hyaluronic acid (HA), which showed a negative correlation with the international normalized ratio of prothrombin coagulation (INR) and liver injury indicator aspartate aminotransferase (AST). For NASH, the diagnostic accuracy of ALT > LAP3 > AST, the sensitivity LAP3 (0.87) > ALT (0.5957) > AST (0.2941), the specificity AST (0.975) > ALT (0.9) > LAP3 (0.5).

CONCLUSION

Our data urge that LAP3 can serve as a promising serum biomarker candidate for NASH diagnosis.

Hepatocyte apoptosis fragment product cytokeratin-18 M30 level and non-alcoholic steatohepatitis risk diagnosis: an international registry study

BACKGROUND

Liver biopsy for the diagnosis of non-alcoholic steatohepatitis (NASH) is limited by its inherent invasiveness and possible sampling errors. Some studies have shown that cytokeratin-18 (CK-18) concentrations may be useful in diagnosing NASH, but results across studies have been inconsistent. We aimed to identify the utility of CK-18 M30 concentrations as an alternative to liver biopsy for non-invasive identification of NASH.

METHODS

Individual data were collected from 14 registry centers on patients with biopsy-proven non-alcoholic fatty liver disease (NAFLD), and in all patients, circulating CK-18 M30 levels were measured. Individuals with a NAFLD activity score (NAS) ≥5 with a score of ≥1 for each of steatosis, ballooning, and lobular inflammation were diagnosed as having definite NASH; individuals with a NAS ≤2 and no fibrosis were diagnosed as having non-alcoholic fatty liver (NAFL).

RESULTS

A total of 2571 participants were screened, and 1008 (153 with NAFL and 855 with NASH) were finally enrolled. Median CK-18 M30 levels were higher in patients with NASH than in those with NAFL (mean difference 177 U/L; standardized mean difference [SMD]: 0.87 [0.69-1.04]). There was an interaction between CK-18 M30 levels and serum alanine aminotransferase, body mass index (BMI), and hypertension ( P  < 0.001, P  = 0.026 and P  = 0.049, respectively). CK-18 M30 levels were positively associated with histological NAS in most centers. The area under the receiver operating characteristics (AUROC) for NASH was 0.750 (95% confidence intervals: 0.714-0.787), and CK-18 M30 at Youden's index maximum was 275.7 U/L. Both sensitivity (55% [52%-59%]) and positive predictive value (59%) were not ideal.

CONCLUSION

This large multicenter registry study shows that CK-18 M30 measurement in isolation is of limited value for non-invasively diagnosing NASH.

N-terminal propeptide of type 3 collagen-based sequential algorithm can identify high-risk steatohepatitis and fibrosis in MAFLD

BACKGROUND AND AIMS

With metabolic dysfunction-associated fatty liver disease (MAFLD) incidence and prevalence sharply increasing globally, there is an urgent need for non-invasive diagnostic tests to accurately screen high-risk MAFLD patients for liver inflammation and fibrosis. We aimed to develop a novel sequential algorithm based on N-terminal propeptide of type 3 collagen (PRO-C3) for disease risk stratification in patients with MAFLD.

METHODS

A derivation and independent validation cohort of 327 and 142 patients with biopsy-confirmed MAFLD were studied. We compared the diagnostic performances of various non-invasive scores in different disease states, and a novel sequential algorithm was constructed by combining the best performing non-invasive scores.

RESULTS

For patients with high-risk progressive steatohepatitis (i.e., steatohepatitis + NAFLD activity score ≥ 4 + F ≥ 2), the AUROC of FAST score was 0.801 (95% confidence interval (CI): 0.739-0.863), and the negative predictive value (NPV) was 0.951. For advanced fibrosis (≥ F3) and cirrhosis (F4), the AUROCs of ADAPT and Agile 4 were 0.879 (95%CI 0.825-0.933) and 0.943 (95%CI 0.892-0.994), and the NPV were 0.972 and 0.992. Sequential algorithm of ADAPT + Agile 4 combination was better than other combinations for risk stratification of patients with severe fibrosis (AUROC = 0.88), with similar results in the validation cohort. Meanwhile, in all subgroup analyses (stratifying by sex, age, diabetes, NAS, BMI and ALT), ADAPT + Agile 4 had a good diagnostic performance.

CONCLUSIONS

The new sequential algorithm reliably identifies liver inflammation and fibrosis in MAFLD, making it easier to exclude low-risk patients and recommending high-risk MAFLD patients for clinical trials and emerging pharmacotherapies.

Dissecting the multifaceted impact of statin use on fatty liver disease: a multidimensional study

BACKGROUND

Statin use could benefit patients with non-alcoholic fatty liver disease (NAFLD), but the evidence is segmented and inconclusive. This multidimensional study comprehensively investigated the potential benefits and mechanism-of-action of statins in NAFLD.

METHODS

A cross-sectional investigation was performed within the Rotterdam Study (general population; n = 4.576) and the PERSONS cohort (biopsy-proven NAFLD patients; n = 569). Exclusion criteria were secondary causes for steatosis and insufficient data on alcohol, dyslipidemia or statin use. Associations of statin use with NAFLD (among entire general population), fibrosis and NASH (among NAFLD individuals and patients) were quantified. These results were pooled with available literature in meta-analysis. Last, we assessed statins' anti-lipid and anti-inflammatory effects in 3D cultured human liver organoids and THP-1 macrophages, respectively.

FINDINGS

Statin use was inversely associated with NAFLD in the Rotterdam study compared to participants with untreated dyslipidemia. In the PERSONS cohort, statin use was inversely associated with NASH, but not with fibrosis. The meta-analysis included 7 studies and indicated a not significant inverse association for statin use with NAFLD (pooled-Odds Ratio: 0.69, 95% Confidence Interval: 0.46-1.01) and significant inverse associations with NASH (pooled-OR: 0.59, 95% CI: 0.44-0.79) and fibrosis (pooled-OR: 0.48, 95% CI: 0.33-0.70). In vitro, statins significantly reduced lipid droplet accumulation in human liver organoids and downregulated expression of pro-inflammatory cytokines in macrophages.

INTERPRETATION

Pooled results demonstrated that statin use was associated with a lower prevalence of NASH and fibrosis and might prevent NAFLD. This may be partially attributed to the anti-lipid and anti-inflammatory characteristics of statins. Given their under-prescription, adequate prescription of statins may limit the disease burden of NAFLD.

FUNDING

ZonMw, KWF, NWO, SLO, DGXII, RIDE, National and regional government, Erasmus MC and Erasmus University.

Noninvasive biochemical markers and surrogate scores in evaluating nonalcoholic steatohepatitis

The histological features of nonalcoholic steatohepatitis (NASH) are the presence of hepatic steatosis with concomitant inflammation, ballooned hepatocytes, and potential fibrosis, which can lead to liver cirrhosis. To reduce the need for liver biopsy, that is still the gold standard for diagnosing NASH, various noninvasive biomarkers have been investigated. This narrative review summarizes the current knowledge about noninvasive diagnostic biomarkers and scores proposed for patients with NASH. A search was performed in the main medical literature databases. The following search terms were used: NASH, noninvasive biomarkers or NASH scores and panels. We focused only on studies assessing NASH diagnosis or predictive values for biomarkers, panels and scores. Data on their accuracy in predicting NASH were collected. Several panels such as NAFLD Fibrosis Score (NFS), Fibrosis-4 (FIB-4), and FibroMeter presented good predictive values of NASH, with novel proteomics panels such as the NAFLD Fibrosis Protein Panel (NFPP) using mainly the adisintegrin and metalloproteinase with thrombospondin motifs like 2 (ADAMTSL2) that showed an advantage in predicting NASH compared to NFS and FIB-4. Another novel panel, Index of NASH (ION) performed better than cytokeratin 18 (CK-18) in excluding severe fibrosis, but the overall accuracy of ION and CK-18 was modest compared to NFS and FIB-4 as it did not provide any significant advantage. Noninvasive biomarkers are currently unable to replace liver biopsy and histological assessment. However, they may play a key and vital role in triaging patients for liver biopsy, lowering the related financial burden. Future studies are needed to verify the predictive values of the newly emerging tests and panels as well as to find more affordable and reliable noninvasive early diagnostic tools.

A Novel Non-Invasive Approach Based on Serum Ceruloplasmin for Identifying Non-Alcoholic Steatohepatitis Patients in the Non-Diabetic Population

Background and Aim

Few non-invasive models were established to identify patients with non-alcoholic steatohepatitis (NASH). Liver biopsy remains the gold standard in the clinic. Decreased serum ceruloplasmin (CP) is reported in patients with non-alcoholic fatty liver disease (NAFLD). We aimed to develop a non-invasive model incorporating CP for identifying NASH from NAFLD without type 2 diabetes mellitus (T2DM).

Methods

A total of 138 biopsy-proven patients with NAFLD without T2DM were enrolled. The CP ratio was calculated for standardization as the CP value divided by the lower limit of normal. The clinical, anthropometric, biochemical, and histological parameters were compared between the low and high CP ratio groups divided by the median value. Multivariate logistic regression analysis was performed to develop a model for identifying NASH in patients with NAFLD.

Results

The medians of the high (n = 69) and low (n = 69) CP ratio groups were 1.43 (1.28–1.61) and 1.03 (0.94–1.12), respectively. A comparison of the two groups showed that the severity of steatosis, hepatocellular ballooning, inflammation activity, fibrosis, and liver iron deposition decreased along with the CP ratio (p &lt; 0.05). The median CP ratio of patients with NASH was significantly lower than those with NAFL [1.15 (1.01–1.41) vs. 1.33 (1.24–1.54), p = 0.001]. A novel model which consists of the CP ratio, BMI, and aspartate aminotransferase (AST) was developed. The AUCs of the model in discriminating NASH from NAFLD was 0.796 (0.694–0.899) and 0.849 (0.713–0.984) in the training and validation groups, and 0.836 (0.659–1.000), 0.833 (0.705–0.962), and 0.821 (0.612–1.000) in patients with normal serum alanine aminotransferase, AST, and both levels, respectively.

Conclusions

Decreased CP ratio is associated with more severe histological activity, a diagnosis of NASH, and hepatic iron deposition among patients with NAFLD without T2DM. The CP ratio model could be served as a non-invasive approach to identifying patients with NASH, which might reduce the need for liver biopsy.

Malaysian Society of Gastroenterology and Hepatology consensus statement on metabolic dysfunction-associated fatty liver disease

The Malaysian Society of Gastroenterology and Hepatology saw the need for a consensus statement on metabolic dysfunction-associated fatty liver disease (MAFLD). The consensus panel consisted of experts in the field of gastroenterology/hepatology, endocrinology, bariatric surgery, family medicine, and public health. A modified Delphi process was used to prepare the consensus statements. The panel recognized the high and increasing prevalence of the disease and the consequent anticipated increase in liver-related complications and mortality. Cardiovascular disease is the leading cause of mortality in MAFLD patients; therefore, cardiovascular disease risk assessment and management is important. A simple and clear liver assessment and referral pathway was agreed upon, so that patients with more severe MAFLD can be linked to gastroenterology/hepatology care, while patients with less severe MAFLD can remain in primary care or endocrinology, where they are best managed. Lifestyle intervention is the cornerstone in the management of MAFLD. The panel provided a consensus on the use of statin, angiotensin-converting enzyme inhibitor or angiotensin receptor blocker, sodium-glucose cotransporter-2 inhibitor, glucagon-like peptide-1 agonist, pioglitazone, vitamin E, and metformin, as well as recommendations on bariatric surgery, screening for gastroesophageal varices and hepatocellular carcinoma, and liver transplantation in MAFLD patients. Increasing the awareness and knowledge of the various stakeholders on MAFLD and incorporating MAFLD into existing noncommunicable disease-related programs and activities are important steps to tackle the disease. These consensus statements will serve as a guide on MAFLD for clinicians and other stakeholders.

Non-invasive tests of non-alcoholic fatty liver disease

ABSTRACT

For the detection of steatosis, quantitative ultrasound imaging techniques have achieved great progress in past years. Magnetic resonance imaging proton density fat fraction is currently the most accurate test to detect hepatic steatosis. Some blood biomarkers correlate with non-alcoholic steatohepatitis, but the accuracy is modest. Regarding liver fibrosis, liver stiffness measurement by transient elastography (TE) has high accuracy and is widely used across the world. Magnetic resonance elastography is marginally better than TE but is limited by its cost and availability. Several blood biomarkers of fibrosis have been used in clinical trials and hold promise for selecting patients for treatment and monitoring treatment response. This article reviews new developments in the non-invasive assessment of non-alcoholic fatty liver disease (NAFLD). Accumulating evidence suggests that various non-invasive tests can be used to diagnose NAFLD, assess its severity, and predict the prognosis. Further studies are needed to determine the role of the tests as monitoring tools. We cannot overemphasize the importance of context in selecting appropriate tests.

Non-invasive assessment of metabolic dysfunction-associated fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) affects an estimated one-quarter of the global adult population and has become one of the leading causes of end-stage liver disease and hepatocellular carcinoma with increased liver-related and overall morbidity and mortality. The new term, metabolic dysfunction-associated fatty liver disease (MAFLD), has a set of positive diagnostic criteria and has been shown to have better clinical utility, but it has yet to be universally adopted. This review addresses the non-invasive tests for MAFLD and is based mostly on studies on NAFLD patients, as the MAFLD term is relatively new and there are limited studies on non-invasive tests based on this new term, while a large body of research work on non-invasive tests has accumulated in the literature for NAFLD. This review focuses on blood-based biomarkers and scores for the assessment of hepatic steatosis, non-alcoholic steatohepatitis (NASH), and fibrosis, and two of the most widely studied imaging biomarkers, namely vibration-controlled transient elastography and magnetic resonance imaging. Fibrotic NASH has become a diagnostic target of interest and novel serum biomarkers and scores incorporating imaging biomarker for diagnosis of fibrotic NASH are emerging. Nonetheless, the degree of liver fibrosis remains the key predictor of liver-related morbidity and mortality in patients with MAFLD. A multitude of non-invasive biomarkers and scores have been studied for the detection of liver fibrosis, including use of sequential non-invasive tests for risk stratification of advanced liver fibrosis. In addition, this review will explore the utility of the non-invasive tests for prognostication and for monitoring of treatment response.

Nonalcoholic Fatty Liver Disease (NAFLD): Pathogenesis and Noninvasive Diagnosis

The global prevalence of nonalcoholic fatty liver disease (NAFLD) or metabolic associated fatty liver disease (MAFLD), as it is now known, has gradually increased. NAFLD is a disease with a spectrum of stages ranging from simple fatty liver (steatosis) to a severe form of steatosis, nonalcoholic steatohepatitis (NASH), which could progress to irreversible liver injury (fibrosis) and organ failure, and in some cases hepatocellular carcinoma (HCC). Although a liver biopsy remains the gold standard for accurate detection of this condition, it is unsuitable for clinical screening due to a higher risk of death. There is thus an increased need to find alternative techniques or tools for accurate diagnosis. Early detection for NASH matters for patients because NASH is the marker for severe disease progression. This review summarizes the current noninvasive tools for NAFLD diagnosis and their performance. We also discussed potential and newer alternative tools for diagnosing NAFLD.

Surrogate markers in non-alcoholic steatohepatitis

Background

Hepatic steatosis with inflammation, inflated hepatocytes, and potential fibrosis defines non-alcoholic steatohepatitis (NASH), which can possibly lead to liver cirrhosis. Although liver biopsy is still the gold standard for diagnosing NASH, numerous non-invasive surrogate markers have been investigated to reduce the need for this invasive technique. In this review we present several currently assessed biomarkers, scores, and indexes in assessing NASH.

Methods

A search in the main medical literature databases was conducted. We searched for observational studies evaluating non-invasive markers, scores, and panels in predicting NASH.

Results

Several proinflammatory markers, inflammation and apoptosis biomarkers, as well as complex models have been studied in predicting NASH. Proinflammatory markers include C-reactive protein, ferritin, tumor necrosis factor-α, interleukin-6, pentraxin-3, and neutrophil extracellular traps. Inflammation and apoptosis biomarkers include cytokineratin-18, adipocytokines, lipid oxidation panels, plasminogen activator inhibitor-1, and products of free radical-mediated oxidation of linoleic acid. Moreover, several studied complex models such as NashTest, NashTest-2, pairing CK18 fragments with other biomarkers such as ALT and the presence of MetS, the HAIR model, acNASH, NAFIC score, Visceral Adiposity Index have also been studied.

Conclusion

A variety of diagnostic panels have shown good predictive values for diagnosing NASH. Nevertheless, non-invasive surrogate markers are currently unable to replace liver biopsy. However, their clinical significance is mainly in triaging patients for liver biopsy, reducing the financial burden associated with the procedure.