Clinical indicators for progression of nonalcoholic steatohepatitis to cirrhosis

Abstract

Non-alcoholic fatty liver disease (NAFLD), is a disease spectrum characterized by fat accumulation in hepatocytes presenting as hepatic steatosis to advance disease with active hepatic inflammation, known as nonalcoholic steatohepatitis. Chronic steatohepatitis will lead to progressive hepatic fibrosis causing cirrhosis and increased risk for developing hepatocellular carcinoma (HCC). Fatty liver disease prevalence has increased at alarming rates alongside obesity, diabetes and metabolic syndrome to become the second most common cause of cirrhosis after alcohol related liver disease worldwide. Given this rise in prevalence, it is becoming increasingly more important to find non-invasive methods to diagnose disease early and stage hepatic fibrosis. Providing clinicians with the tools to diagnose and treat the full spectrum of NAFLD will help prevent known complications such as cirrhosis and HCC and improve quality of life for the patients suffering from this disease. This article discusses the utility of current non-invasive liver function testing in the clinical progression of fatty liver disease along with the imaging modalities that are available. Additionally, we summarize available treatment options including targeted medical therapy through four different pathways, surgical or endoscopic intervention.

Key Words: Nonalcoholic fatty liver disease, Steatosis, Hepatitis, Cirrhosis, Hepatocellular carcinoma, Liver function tests, Imaging, Histopathology

Core Tip: Fatty liver disease rates along with obesity, diabetes and metabolic syndrome continue to increase and now is the second leading cause of cirrhosis secondary to alcohol related liver disease. The need for consistent and readily available methods to accurately diagnose and stage hepatic fibrosis becomes increasingly necessary. With an up to date armamentarium to diagnose and treat the full spectrum of non-alcoholic fatty liver disease will decrease complications such as cirrhosis and hepatocellular carcinoma and will improve the likelihood for patients to have a higher quality of life.

INTRODUCTION

Nonalcoholic fatty liver disease (NAFLD) was first introduced by Schaffner and Thaler[1] in 1986. They assembled a group of non-alcoholic patients with liver diseases and biopsy specimens of liver pathology similar to that of alcoholic liver disease. They defined these subsets of patients as NAFLD. Over the last 20 years, the “non-alcoholic” portion of the diagnosis has been heavily criticized, as it carries an unfavorable connotation for patients that may negatively impact their overall care. In 2019, a group of international experts suggested the term metabolic (dysfunction) associated fatty liver disease “MAFLD” as a more appropriate diagnosis for NAFLD. As the underlying pathology is more related to metabolic dysfunction rather than the exclusion of alcohol[2]. Over the decades, NAFLD has grown to become the second most common cause of liver cirrhosis after alcohol related liver disease. The prevalence of NAFLD has grown every year in the United States secondary to a rise in diabetes, obesity and metabolic syndrome, with an incidence of 31% in 2012 as opposed to 18% in 1988–1991[3,4]. NAFLD refers to a spectrum of liver injury due to accumulation of triglycerides in hepatocytes presenting as a spectrum of conditions, ranging from a simple hepatic steatosis characterized by fat accumulation in the absence of hepatic inflammation to a more severe disease form characterized by active hepatic inflammation, also known as nonalcoholic steatohepatitis (NASH). Progressive hepatic inflammation will lead to cirrhosis and increase the risk of developing hepatocellular carcinoma (HCC) as shown in (Figure 1). Up to 1/3 of NAFLD patients will have NASH which is a risk factor for fibrosis progression, and approximately 40% of NASH patients will experience fibrosis progression[5]. The recent estimated annual progression of fibrosis from NAFLD is up to 0.09% with an incidence of advanced fibrosis as 70 per 1000 patients[6]. The high prevalence of NASH among the biopsied patients could be explained secondary to the indication for biopsy in these patients with elevated liver function tests (LFTs), and the data cannot be extrapolated to the subset of NAFLD patients with normal LFTs where biopsy is not performed often. In the same study, the prevalence of NASH in patients without indication for biopsy was 6.7%[5]. The annual incidence of HCC in NAFLD patients is 44% per 1000 person-years. NAFLD-related HCC amounts to about 2% to 4% of annual cases[7].

Figure 1 Histologic progression of nonalcoholic fatty liver disease from simple steatosis to cirrhosis.

Liver biopsy is not always performed and the diagnosis is often made with available non-invasive tests including blood tests and elastography [magnetic resonance elastography (MRE), Fibroscan]. Advantages of fibroscan, other than being a non-invasive modality that helps in sequential assessment of progression or regression of steatosis/fibrosis, include elimination of sampling error experienced by liver biopsy. Liver biopsy is the gold standard in confirming the diagnosis of NAFLD and allowing accurate hepatitis fibrosis staging. The major histologic features include steatosis, lobular inflammation, and cytological ballooning; these findings help in grading and staging the disease[8,9]. Moreover, the diagnostic tests especially non-invasive fibrosis assessment testing helps to monitor NAFLD stages to prevent disease progression and diagnose cancer early. Our review article discusses the indicators that help in understanding the progression of the disease including symptomatic worsening, liver function testing, imaging, and histopathological changes.

REVIEW

NAFLD encompasses a spectrum of conditions which ranges from bland hepatic steatosis to steatohepatitis causing hepatic fibrosis which will lead to cirrhosis, liver failure and increase the risk of HCC. The risk factors of fatty liver disease are similar to those of metabolic syndrome which leads to insulin resistance[5]. This includes diabetes mellitus, dyslipidemia and elevated body mass index (BMI). It is important to distinguish simple hepatic steatosis, which carries very low risk of developing chronic disease and cirrhosis vs NASH which carries a risk of progressive fibrosis, cirrhosis, liver failure and HCC. Overall, one fifth of NASH patients can progress to advanced hepatic fibrosis[10-12]. Hence, the assessment of the degree of hepatic fibrosis with noninvasive diagnostic panels and imaging is important in monitoring disease progression. Several scoring systems and specialized biomarkers have been developed by combining various serologic and clinical parameters for the prediction of fibrosis in NAFLD[13-18]. Despite the advancement of many diagnostic noninvasive fibrosis assessment modalities, one fourth of advanced fibrosis NASH patients can be misclassified as mild hepatic fibrosis[14].

The mortality of NAFLD is not merely targeting the liver. The majority of NAFLD patients are at risk of developing atherosclerotic coronary artery disease carrying higher mortality rate approaching[19]. Understanding patients’ risk factors and stage of hepatic fibrosis can help predict patients’ clinical outcomes[10]. Multiple clinical indicators and serological markers of disease progression remains an area of intensive clinical and basic science research till this day (Tables 1 and 2).

Table 1 Role of noninvasive liver function testing in clinical progression of nonalcoholic steatohepatitis.

Sr. No.	Indicator	Ref.	Journal	Year	Results
1	Bilirubin	Demir et al[24]	PLoS One	2013	Total bilirubin was identified as a significant predictor of advanced fibrosis and used to construct the NIKEI score which can reliably exclude advanced fibrosis in subjects with NAFLD
		Ratziu et al[25]	BMC Gastroenterol	2006	FibroTest which includes total bilirubin in its panel is a simple and noninvasive quantitative estimate of liver fibrosis which reliably predicts advanced fibrosis
		Adams et al[11]	J Hepatol	2005	Hepascore, a model of 4 serum markers plus age and sex provides clinically useful information regarding different fibrosis stages among hepatitis C patients
2	Serum AST/ALT	Martin-Rodriguez et al[20]	Medicine (Baltimore)	2017	Serum ALT level is the most predictive laboratory investigation for the NAFLD. The AST-ALT Ratio (AAR) is higher in increasing liver fat content, fibrosis and other metabolic derangements like diabetes and dyslipidemia
		Enomoto et al[21]	World J Gastroenterol	2015	AAR > 1 is consistent with NASH
		Arora et al[22]	J Clin Exp Hepatol	2012	AAR > 1 may indicate the progression of NAFLD and aid in diagnosing liver fibrosis
		Shah et al[17]	Clin Gastroenterol Hepatol	2009	The FIB-4 score composed of age, AST and ALT and platelet counts is an invasive and inexpensive method which has shown superiority to BAAT (BMI, Age, ALT, Triglycerides) and BARD (BMI, AST: ALT, Diabetes) scores in monitoring the progress of NASH
		McPherson et al[18]	Eur J Gastroenterol Hepatol	2013	The FIB-4 score was reliable in ruling out advanced fibrosis in patients with histological evidence of NAFLD who had normal or increased levels of ALT, thus decreasing the need for invasive liver biopsy
3	Platelet Count	Enomoto et al[21]	World J Gastroenterol	2015	A reducing level of platelet count has been well documented in advancing liver diseases
		Kawamura et al[26]	Hepatol Int	2015	FSN score of 17 variables including platelet count could accurately predict fibrotic stage and discriminates patients with advanced fibrosis of NASH
		Kessoku et al[27]	World J Gastroenterol	2014	PLALA Score is a very unique scoring system as it has shown usefulness in distinguishing cirrhosis in NAFLD when compared with most fibrosis scoring systems
		Abdel-Razik A et al[47]	Eur J Gastroenterol	2016	MPV is a noninvasive novel marker to predict advanced disease as it was increased in NASH patients and advance liver fibrosis
		Cengiz et al[48]	Eur J Gastroenterol	2015	Red cell volume distribution width-to-platelet ratio was both correlated and able to predict liver fibrosis. It may reduce liver biopsy in NAFLD
4	Fasting blood glucose and glycosylated protein	Pelusi et al[49]	PLoS One	2016	Nonalcoholic steatohepatitis with greater degree of fibrosis was discovered in patients with insulin resistance. Type 2 diabetes in patients with NAFLD tends to drive the rate of fibrosis
5	Hyaluronic acid (hyluroante) tissue metaloproteinase	Arora et al[22]	J Clin Exp Hepatol	2012	European Liver Fibrosis score ELF scoring system has indicators for cellular matrix activities including Hyaluronic acid (hyluroante) tissue metalloproteinase which has been indicative of fibrosis
6	Type IV collagen	Nakamura et al[30]	J Diabetes Investig	2013	NAFIC Score including type IV collagen 7S and Modified NAFIC score were proven to be clinically useful in screening for NASH in NAFLD patients
7	Glycosylated Albumin to Glycosylated Hemoglobin Ratio	Hu et al[28]	World J Gastroenterol	2014	HOMA-IR score indicates NAFLD progression using a formula that involves insulin levels and fasting glucose to calculate insulin resistance. The score has a high sensitivity for NASH
		Stål[29]	World J Gastroenterol	2015	NAFLD fibrosis score, a non- invasive score which includes the presence of diabetes or impaired fasting glucose is the most predictive of mortality in NASH as compared to NAFL patients
8	Prothrombin time	Assy et al[31]	World J Gastroenterol	2005	Increase prothrombin time is usually associated with cirrhotic changes
9	Albumin	Bazick et al[5]	Diabetes Care	2015	Serum albumin gets reduced in patients progressing to NASH and fibrosis from NAFLD

ALT: Alanine aminotransferases; BMI: Body mass index; NAFIC: Nonalcoholic steatohepatitis, ferritin, insulin, and type IV collagen 7S; NASH: Nonalcoholic steatohepatitis; AAR: Aspartate aminotransferases-alanine aminotransferases ratio; RPR: Red cell volume distribution width-to-platelet ratio; NFS: Non-alcoholic fatty liver disease fibrosis score; NIKEI: Non-invasive koeln-essen-index; NAFLD: Non-alcoholic fatty liver disease.

Table 2 Role of imaging techniques in clinical progression of nonalcoholic steatohepatitis.

Sr. No.	Imaging modality	Ref.	Journal	Year	Results
1	Ultrasound	Sanyal[32]	Gastroenterology	2002	US is currently the preferred method in United States for screening asymptomatic patients with elevated liver enzymes and suspected NAFLD with sensitivity in detecting steatosis varying between 60%–94%
2	Magnetic Resonance Elastography	Iijima et al[35]	Hepatol Res	2007	Magnetic resonance elastography has excellent diagnostic accuracy with sensitivity and specificity of 98% and 99%, respectively, for detecting all grades of fibrosis
		Huwart et al[36]	Gastroenterology	2008	Magnetic resonance elastography was associated with a higher technical success rate than US elastography
3	Fibroscan	Wong et al[39]	Gut	2012	Transient elastography had shown good results in patients with NAFLD. It is a non-invasive method of assessing liver fibrosis which can be performed at the bedside or in the outpatient clinic
		Wong et al[40]	Hepatology	2010	Transient elastography had shown good results in patients with NAFLD. It is a non-invasive method of assessing liver fibrosis which can be performed at the bedside or in the outpatient clinic
		Ratziu et al[43]	Gastroenterology	2005	Fibroscan has now been validated in NAFLD, and represents a useful tool for rapid, non-invasive assessment of liver fibrosis and determining the need for biopsy. Nonetheless, fibroscan values should be interpreted in consonance with clinical, biological, and morphological data

US: Ultrasonography; NAFLD: Non-alcoholic fatty liver disease.

ROLE OF NONINVASIVE LIVER FUNCTION TESTING IN CLINICAL PROGRESSION OF NASH

Clinical assessment in progression of nash

NASH is a histological diagnosis characterized by hepatocytic inflammation that may progress to fibrosis. Hepatic fibrosis divided into four stages. Stage I describes as mild hepatic fibrosis, stage II moderate hepatic fibrosis, stage III moderate to severe fibrosis, and stage IV severe or advanced fibrosis. It is crucial to identify advanced fibrosis stage as these patients are at-risk to develop decompensated cirrhosis and end-stage liver disease. A number of clinical factors help clinicians to predict the likelihood of the patient progressing into devastating categories of this disease.

Role of liver chemistry in the clinical progression of NAFLD

Liver chemistry test identify active hepatic inflammation. This includes alanine aminotransferases (ALT) and aspartate aminotransferases (AST), alkaline phosphatase (ALP) and direct and indirect bilirubin. Other laboratory data should be monitored in NASH patients are platelet count and coagulation panel, fasting blood glucose and glycosylated proteins and lipid panel. Serum hyaluronic acid tissue metalloproteinase, and type 4 collagen are serological markers help in assessing fibrosis stage.

AST and ALT: In a cross-sectional study, Martin-Rodriguez et al[20] reported that serum ALT level is the most predictive laboratory investigation for NAFLD. The AST-ALT Ratio (AAR) is higher in increased liver fat content, fibrosis, and other metabolic derangements like diabetes and dyslipidemia. Steatosis or steatohepatitis can be observed, but nevertheless patients have normal serum ALT levels[8]. An AAR > 1 is consistent with a diagnosis of NASH. This forms the basis of several other laboratory combinations that may indicate the progression of NAFLD and diagnosing liver fibrosis including BAAT (which uses BMI, age, ALT, and triglycerides), BARD (which uses BMI, AST: ALT, and diabetes), and FIB-4 scores[21,22]. The FIB-4 score is a simple, noninvasive and inexpensive test superior to BAAT and BARD scores in monitoring the progress of NASH[17]. The FIB-4 score is reliable in ruling out advanced fibrosis in patients with histological evidence of NAFLD who had normal or increased levels of ALT, thus decreasing the need for invasive liver biopsy with sensitivity 84%-94%[18].

ALP: Few subsets of NASH patients present with an isolated ALP elevation[23]. Cholestasis also has been noted on histology in NASH[23]. Elevated ALP should be accompanied by an increase in γ-glutamyltransferase (GGT) enzyme suggesting hepatic inflammation. Otherwise elevated ALP without GGT elevation are seen in pregnancy, muscular disease and bone disease such as Paget’s disease.

Bilirubin: Bilirubin is synthetic marker for liver function alongside with PT/INR. Also, it is a part of various scoring system used to estimate the degree of fibrosis. Demir et al[24] introduced the non-invasive koeln-essen-index (NIKEI) score which uses age, AST, AST/ALT ratio, and total bilirubin. In a prospective study by Ratziu et al[25], the diagnostic utility of FibroTest, a noninvasive marker of fibrosis, was determined in a sample of 170 patients with NAFLD. The FibroTest includes α-2-macroglobulin, apolipoprotein A1, haptoglobin, total bilirubin, and γ-glutamyl-transpeptidase. Ratziu concluded this simple and noninvasive quantitative estimate of liver fibrosis reliably predicts advanced fibrosis[25]. Hepascore, a combination of bilirubin, γ-glutamyl-transpeptidase, hyaluronic acid, and 2-macroglobulin together with age and sex, is an accurate and reliable panel in predicting different stages of fibrosis. However, the limitation of this study included validation of this score among only patients with hepatitis C[21]. NIKEI had superior negative predictive value for advanced fibrosis compared to the FIB-4 score (which uses age, AST, ALT, and platelet counts)[24].

Platelet count: Platelet count has great value in assessing degree of fibrosis. Thrombocytopenia occurs in cirrhosis secondary to thrombopoietin deficiency and splenic sequestration from underlying splenomegaly occurring from portal hypertension. Platelet level has been used in combination with other biochemical parameters such as in AST/platelet ratio index and FIB-4 score to monitor liver disease progression[21]. Kawamura established the fibrosis score for NASH (FSN), a new scoring system specific to the fibrotic stage of NASH[26]. FSN can accurately predict the fibrotic stage and distinguishes patients with advanced fibrosis of NASH. The platelet albumin AAR (PLALA) score is unique in that it distinguishes cirrhosis in NAFLD compared to most other fibrosis scoring systems. Each factor (platelet count < 15.3 × 10⁴ /µL; albumin < 4 g/dL; AAR > 0.9) is awarded 1 point, and a PLALA score of 2 or 3 may be predictive of cirrhosis in patients with NAFLD[27]. The PLALA score may be an ideal scoring system for detecting cirrhosis in NAFLD patients with sufficient accuracy and simplicity for clinical use. Mean platelet volume (MPV) was elevated in NASH and advanced liver fibrosis (stages 3–4) patients, making MPV a noninvasive, novel marker to predict advanced disease. Another study looked into the performance of red cell volume distribution width-to-platelet ratio in predicting liver fibrosis in patients with NAFLD[27]. This ratio was both correlated and able to predict liver fibrosis.

Fasting blood glucose and glycosylated protein: In their observational cohort of 118 patients, assessing the clinical determinants of fibrosis progression rate in NAFLD patients with baseline and follow-up histological evaluation. Advanced fibrosis is more likely to be found in patients with underlying type 2 diabetes[28]. These patients had histological evidence of more inflammation in the fibrous portal areas in those already developing cirrhosis than those at an earlier stage of the disease. Furthermore, this study also observed that type 2 diabetes can drive fibrosis in the absence of hepatic inflammation.

Glycosylated albumin to glycosylated hemoglobin ratio: Glycosylated albumin (GA) and glycosylated hemoglobin (HbA1c), which are indicators of glycemic control, show a strong relationship with advanced liver fibrosis. The GA/HbA1c ratio, which is typically 3 in a healthy individual, is higher in liver fibrosis patients. Patients with chronic liver diseases have reduced albumin turnover resulting in an elevated level of GA. Also, they have a reduced erythrocyte lifespan which accounts for changes in the increased ratio. The GA/HbA1c ratio’s accuracy in detecting liver fibrosis might be limited by other concurrent diseases that can affect plasma and hemoglobin levels[25]. The HOMA-insulin resistance score is a somewhat rigorous and reliable scoring system that indicates NAFLD progression using a formula that involves insulin levels and fasting glucose to calculate insulin resistance[28]. The HOMA-insulin resistance score has a high sensitivity for NASH. The NAFLD fibrosis score (NFS) is a noninvasive score (using age, albumin, AST/ALT ratio, BMI, the presence of diabetes or impaired fasting glucose, and platelet count) most predictive of mortality in NASH compared to NAFLD[29]. As of 2015, the NFS score was endorsed by the American Association for the Study of Liver Diseases, American College of Gastroenterology, and the American Gastroenterological Association as a screening guideline in clinical practice. These screening tools may be more important in detecting NASH in people with diabetes.

Hyaluronic acid tissue metalloproteinase: A high level of hyaluronic acid (hyaluronate) tissue metalloproteinase 1 has been indicative of fibrosis. The European liver fibrosis scoring system has indicators for cellular matrix activities including age, the amino-terminal peptide of procollagen III, tissue metalloproteinase 1 inhibitor, and hyaluronic acid[22].

Type IV collagen: The FSN score, which includes type IV collagen 7S, platelet count, AST, and ALT, has been more efficient in distinguishing the advanced fibrosis stages 3–4 of NASH compared to other scoring systems including APRI (AST to platelet ratio index), NAFLD Score, FIB-4 Index, BARD, and NIKEI[26]. The nonalcoholic steatohepatitis, ferritin, insulin, and type IV collagen 7S (NAFIC) score, and modified NAFIC score were proven to be clinically useful in screening for fatty liver patients[30].

Albumin: Bazick et al[5] demonstrated that serum albumin gets reduced drastically in patients presenting with NASH. Their clinical variable could be used to guide clinical decision making about referring patients with diabetes and NAFLD to hepatologists[5].

Prothrombin time: In a study by Assy et al[31], up to 46% of patients with NAFLD showed thrombotic risk factors. The presence of thrombotic risk factors correlated with the extent of hepatic fibrosis. This is consistent with known coagulopathy in those with altered synthetic function due to hepatic fibrosis.

ROLE OF IMAGING TECHNIQUES IN THE CLINICAL PROGRESSION OF NASH

Noninvasive techniques such as ultrasonography (US), computed tomography, magnetic resonance imaging, and proton magnetic resonance spectroscopy can detect hepatic steatosis but cannot reliably distinguish simple steatosis from NASH[32].

Liver US

US is the preferred cost effective method in the United States for screening patients with suspected NAFLD. The findings on US include: diffuse increase in echogenicity of the liver parenchyma, hepatomegaly and vascular blunting[33]. The sensitivity of US in detecting hepatic steatosis up to 94%. The sensitivity decreases as the degree of steatosis dropped below 30%[33-35]. US cannot differentiate between simple hepatic steatosis vs NASH. Thus, laboratory serological and histological data is helpful in pointing towards NASH[22].

MRE

MRE stands for magnetic resonance elastography which is an imaging technique that combines MRI imaging with low-frequency vibrations to measure hepatic stiffness. MRE equivalent of transient elastography has recently demonstrated excellent diagnostic accuracy. It has shown a sensitivity and specificity of 98% and 99%, respectively, for detecting all grades of fibrosis[35]. Huwart et al[36] conducted a prospective blind comparison of MRE, US elastography, and APRI (AST to platelet ratio index) in a study of 141 patients who underwent liver biopsy for chronic liver disease. They found MRE was associated with a higher technical success rate than US elastography[36].

Fibroscan

Transient Elastography (Fibroscan, Echosens, Paris, France) is a noninvasive method of assessing liver fibrosis. It can be performed at the bedside or in the outpatient clinic. It employs US-based technology to measure liver stiffness and has been validated for use in patients with chronic hepatitis C and B[37,38]. However, studies have shown good results in patients with NAFLD[39,40]. In only 5% of the cases, it has failed to show any readings. This is mostly seen in obese patients. This limits the TE’s utility in the NAFLD cohort. However, a recently introduced XL probe may reduce this problem[41]. In a meta-analysis for NASH with advanced fibrosis, pooled area under the receiver operating characteristic curve, sensitivity and specificity of NFS, and fibroscan are 0.85 (0.80-0.93), 0.90 (0.82-0.99), 0.97 (0.94-0.99), and 0.94 (0.90-0.99), 0.94 (0.88-0.99) and 0.95 (0.89-0.99), respectively[16]. Fibroscan is validated in NAFLD and represents a useful tool for rapid, noninvasive assessment of liver fibrosis and determining the need for biopsy. As this modality evaluates liver stiffness (related to fibrosis, inflammation, and portal hypertension), Fibroscan values should be interpreted in context of the morphological, biological, and clinical data.

ROLE OF LIVER BIOPSY IN THE CLINICAL PROGRESSION OF NASH

A percutaneous liver biopsy is currently the gold standard to assess hepatic fibrosis and inflammation in chronic liver disease[42]. However, liver biopsy is an invasive procedure with associated costs, complications, and inherent inaccuracy due to sampling error and inter-observer and intra-observer variability in histopathological interpretation[42,43]. Despite the criticism of liver biopsy’s associated risks, there are 3 basic histological systems that can be used to monitor the progression of NASH (Figure 2). These systems are the steatosis activity and fibrosis score, the NASH activity score, and the Brunt system that grades and stages NASH (Table 3)[28,44]. Due to the risks and limitations associated with liver biopsy, it is controversial to perform liver biopsy on every patient suspected of having NAFLD. Therefore, it cannot be considered a “screening” tool[45]. However, there are studies that support the importance of liver biopsy. An older study, by Skelly et al[46] showed that biopsy on 354 patients with abnormal liver tests-66% had fatty liver, 50% of those had steatohepatitis, and approximately 19% of the remaining biopsies had other treatable causes diagnosed by the pathology evaluation. This included autoimmune hepatitis, primary biliary cirrhosis, hemochromatosis and alcoholic liver disease. An adequate liver biopsy, with appropriate clinical history, interpreted by a trained liver pathologist, is not only pivotal for an accurate and complete diagnosis (or exclusion) of NAFLD (or NASH), but also is optimal for obtaining detailed information regarding disease pattern, severity and fibrosis. It not only provides important information with respect to subtypes, potential future risks, possible etiology, and natural history of disease, but also sets the groundwork for future molecular studies and clinical trials, assisting clinical colleagues and patients with treatments and follow-up[47-49].

Figure 2 The spectrum of nonalcoholic fatty liver disease. NAFL: Nonalcoholic fatty liver; NASH: Nonalcoholic steatohepatitis; HCC: Hepatocellular carcinoma.

Table 3 Nonalcoholic steatohepatitis activity score; steatosis, activity, and fibrosis score; and brunt grading and staging systems.

NASH activity score	Steatosis, activity and fibrosis score	Brunt grading and staging
Steatosis grade 0-3	Steatosis S0-S3	Grade 1 (Mild)
Lobular inflammation 0-3	Activity A1-A3	Grade 2 (Moderate)
Ballooning 0-2	Lobular inflammation 0-2	Grade 3 (Severe)
Fibrosis 0-4 (grade 1 has subgrade A, B, C)	Ballooning 0-2	Stages fibrosis
	Fibrosis F0-F4	Stage 1-4

NASH: Nonalcoholic steatohepatitis.

CONCLUSION

NASH-related cirrhosis is the most common cause of chronic liver disease and indication for liver transplant. The increasing number of affected people imposes a strain on available organs. There are many comorbidities and risk factors implicated in NASH severity and progression to chronic liver disease.

Due to the increasing prevalence of NAFLD in the population, there is an increasing need to find non- invasive methods to diagnose and stage NAFLD. The ideal test should be reproducible, cheap, and able to diagnose full spectrum of NAFLD, predict fibrosis, and reflect changes that occur with treatment. Preliminary evaluation includes clinical presentation with consideration of comorbidities and liver function test in the blood. Noninvasive imaging such as MRE and fibroscan can provide objective measures of liver steatosis and stiffness in patients without advanced fibrosis or cirrhosis. Due to the limitations, risks and cost of liver biopsy-it cannot be used as a screening test, although is typically relied upon to confirm the diagnosis. Several different methodologies including imaging modalities, serum markers and combined tests are currently being investigated.