Comparison of noninvasive markers of fibrosis in patients with nonalcoholic fatty liver disease

Physiologic frailty and fragility fracture in HIV-infected male veterans

BACKGROUND

The Veterans Aging Cohort Study (VACS) Index is associated with all-cause mortality in individuals infected with human immunodeficiency virus (HIV). It is also associated with markers of inflammation and may thus reflect physiologic frailty. This analysis explores the association between physiologic frailty, as assessed by the VACS Index, and fragility fracture.

METHODS

HIV-infected men from VACS were included. We identified hip, vertebral, and upper arm fractures using ICD-9-CM codes. We used Cox regression models to assess fragility fracture risk factors including the VACS Index, its components (age, hepatitis C status, FIB-4 score, estimated glomerular filtration rate, hemoglobin, HIV RNA, CD4 count), and previously identified risk factors for fragility fractures.

RESULTS

We included 40 115 HIV-infected male Veterans. They experienced 588 first fragility fractures over 6.0 ± 3.9 years. The VACS Index score (hazard ratio [HR], 1.15; 95% confidence interval [CI], 1.11-1.19), white race (HR, 1.92; 95% CI, 1.63-2.28), body mass index (HR, 0.94; 95% CI, .92-.96), alcohol-related diagnoses (HR, 1.65; 95% CI, 1.26-2.17), cerebrovascular disease (HR, 1.95; 95% CI, 1.14-3.33), proton pump inhibitor use (HR, 1.87; 95% CI, 1.54-2.27), and protease inhibitor use (HR, 1.25; 95% CI, 1.04-1.50) were associated with fracture risk. Components of the VACS Index score most strongly associated with fracture risk were age (HR, 1.40; 95% CI, 1.27-1.54), log HIV RNA (HR, 0.91; 95% CI, .88-.94), and hemoglobin level (HR, 0.82; 95% CI, .78-.86).

CONCLUSIONS

Frailty, as measured by the VACS Index, is an important predictor of fragility fractures among HIV-infected male Veterans.

Allostasis in nonalcoholic fatty liver disease: implications for risk assessment

Allostasis, a concept of anticipatory physiological regulation in response to external and internal challenges, was originally developed in the context of neuroendocrinology and behavioral medicine. Allostasis preserves function under changing conditions by abandoning physiological set points and developing new ones. Allostatic load refers to the aggregate effect of adaptation throughout life, and corresponds to the wear and tear associated with this process. In response to chronic stress, allostatic load may accumulate faster than expected if sustained activation of regulatory systems exceeds optimum operating ranges; this results in increased risk of disease. Used in a broader sense, the allostatic model of adaptive responses, trade-offs, feed-forward cycles, and collateral damage provides a framework for assessing the involvement of environmental-genetic interactions and co-morbidities in the course of chronic disease and developing a comprehensive score for personalized risk prediction. The utility of this approach is illustrated for nonalcoholic fatty liver disease, a prevalent condition with common and less common outcomes.

Markers in nonalcoholic steatohepatitis

Nonalcoholic fatty liver disease (NAFLD), the most common liver disorder worldwide, encompasses a spectrum of abnormal liver histology ranging from simple steatosis to nonalcoholic steatohepatitis (NASH) and cirrhosis. Population studies show that NAFLD is strongly associated with insulin resistance, obesity, type 2 diabetes mellitus, and lipid abnormalities. In the context of hepatic steatosis, factors that promote cell injury, inflammation, and fibrosis include oxidative stress, early mitochondrial dysfunction, endoplasmic reticulum stress, iron accumulation, apoptosis, adipocytokines, and stellate cell activation. The exact NASH prevalence is unknown because of the absence of simple noninvasive diagnostic tests. Although liver biopsy is the "gold standard" for the diagnosis of NASH, other tests are needed to facilitate the diagnosis and greatly reduce the requirement for invasive liver biopsy. In addition, the development of new fibrosis markers in NASH is needed to facilitate the assessment of its progression and the effectiveness of new therapies. The aim of this chapter, which is overview of biomarkers in NASH, is to establish a systematic approach to laboratory findings of the disease.

Liver stiffness measurement using XL probe in patients with nonalcoholic fatty liver disease

OBJECTIVES

Liver stiffness measurement (LSM) by transient elastography is a noninvasive test of liver fibrosis, but cannot be performed in a significant proportion of obese patients. The aim of this study was to evaluate the performance of the new XL probe in patients with nonalcoholic fatty liver disease (NAFLD).

METHODS

Liver biopsy and paired LSM by both the original M probe and XL probe were performed on 193 consecutive NAFLD patients in France and Hong Kong.

RESULTS

Compared with M probe, XL probe was more likely to achieve 10 valid measurements (95% vs. 81%; P<0.001) and a success rate of over 60% (90% vs. 74%; P<0.001). The areas under receiver operating characteristics curves of XL probe for F2, F3, and F4 disease were 0.80, 0.85, and 0.91, respectively. XL probe tended to generate lower LSM than M probe in the same patient. At a cutoff of 7.2 kPa, the sensitivity, specificity, positive, and negative predictive values for F3 or greater disease were 78%, 78%, 60%, and 89%, respectively. Discordance of at least two stages between XL probe and histology was observed in 16 (9%) patients. Body mass index (BMI) over 35 kg/m(2) was independently associated with discordance (adjusted odds ratio 9.09; 95% confidence interval 1.10-75.43). Reliable measurements by XL probe were obtained in 75% of the overall population and 65% of patients with BMI over 30 kg/m(2).

CONCLUSIONS

LSM by XL probe can be performed successfully in most NAFLD patients, but obesity is associated with less accurate and reliable measurements.

Rapid development of systemic insulin resistance with overeating is not accompanied by robust changes in skeletal muscle glucose and lipid metabolism

Prolonged overeating and the resultant weight gain are clearly linked with the development of insulin resistance and other cardiometabolic abnormalities, but adaptations that occur after relatively short periods of overeating are not completely understood. The purpose of this study was to characterize metabolic adaptations that may accompany the development of insulin resistance after 2 weeks of overeating. Healthy, nonobese subjects (n = 9) were admitted to the hospital for 2 weeks, during which time they ate ∼4000 kcals·day(-1) (70 kcal·kg(-1) fat free mass·day(-1)). Insulin sensitivity was estimated during a meal tolerance test, and a muscle biopsy was obtained to assess muscle lipid accumulation and protein markers associated with insulin resistance, inflammation, and the regulation of lipid metabolism. Whole-body insulin sensitivity declined markedly after 2 weeks of overeating (Matsuda composite index: 8.3 ± 1.3 vs. 4.6 ± 0.7, p < 0.05). However, muscle markers of insulin resistance and inflammation (i.e., phosphorylation of IRS-1-Ser(312), Akt-Ser(473), and c-Jun N-terminal kinase) were not altered by overeating. Intramyocellular lipids tended to increase after 2 weeks of overeating (triacylglyceride: 7.6 ± 1.6 vs. 10.0 ± 1.8 nmol·mg(-1) wet weight; diacylglyceride: 104 ± 10 vs. 142 ± 23 pmol·mg(-1) wet weight) but these changes did not reach statistical significance. Overeating induced a 2-fold increase in 24-h insulin response (area under the curve (AUC); p < 0.05), with a resultant ∼35% reduction in 24-h plasma fatty acid AUC (p < 0.05). This chronic reduction in circulating fatty acids may help explain the lack of a robust increase in muscle lipid accumulation. In summary, our findings suggest alterations in skeletal muscle metabolism may not contribute meaningfully to the marked whole-body insulin resistance observed after 2 weeks of overeating.

Suboptimal performance of simple noninvasive tests for advanced fibrosis in Chinese patients with nonalcoholic fatty liver disease

OBJECTIVE

To evaluate the diagnostic accuracy of some noninvasive fibrosis models in Chinese patients with nonalcoholic fatty liver disease (NAFLD).

METHODS

Consecutive biopsy-proven NAFLD patients were recruited from a single center from January 2005 to December 2010. Advanced fibrosis (stage 3 and 4) was defined using Kleiner criteria. The area under the receiver operating characteristic curve (AUROC) was used to compare the diagnostic accuracy of the NAFLD fibrosis score (NFS), FIB-4 index, aspartate transaminase (AST)/platelet ratio index (APRI), AST/alanine transaminase (ALT) ratio (AAR) and body mass index (BMI)-AAR-Diabetes (BARD) score.

RESULTS

Of the patients with NAFLD, 79.6% were males with a mean age of 37.1 years, mean BMI of 26.1 kg/m(2) and 41.4% of them had nonalcoholic steatohepatitis, and 24 (15.8%) had advanced fibrosis. The AUROC of the FIB-4 index, APRI, AAR, NFS and BARD score for advanced fibrosis were 0.756, 0.742, 0.670, 0.653 and 0.642 (P < 0.05 for all), respectively. A concordant negative predictive value of approximately 90% was indicated whereas the positive predictive values were modest for all tests, and only the FIB-4 index yielded a higher positive likelihood ratio of 7.65. Using these cut-off values of tests for excluding advanced fibrosis could reduce the use of liver biopsy in 56.6-74.3% of the patients, with a minor false negative rate of 5.3-9.9%.

CONCLUSIONS

Although slightly less accurate than liver biopsy, simple noninvasive tests can reliably exclude advanced fibrosis in Chinese NAFLD patients in our center. FIB-4 index performs better than the other tests under examination.

Pathophysiological analysis of nonalcoholic fatty liver disease by evaluation of fatty liver changes and blood flow using xenon computed tomography: can early-stage nonalcoholic steatohepatitis be distinguished from simple steatosis?

INTRODUCTION

Effective noninvasive tests that can distinguish early-stage nonalcoholic steatohepatitis (NASH) from simple steatosis (SS) have long been sought. Our aim was to determine the possibility of noninvasively distinguishing early-stage NASH from SS.

MATERIALS AND METHODS

We used Fick's principle and the Kety-Schmidt equation to determine the hepatic tissue blood flow (TBF) in 65 NASH patients who underwent xenon computed tomography (Xe-CT). We calculated the lambda value (LV), i.e., Xe gas solubility coefficient, in liver and blood. We assessed the histological severity of fatty changes and fibrosis on the basis of Brunt's classification. Liver biopsy revealed SS in 9 patients and NASH in 56 patients. NASH stages 1 and 2 were classified as early-stage NASH (Ea-NASH; 38 patients) and stages 3 and 4 as advanced-stage NASH (Ad-NASH; 18 patients). We evaluated the differences in LV and TBF among the 3 groups.

RESULTS

LV was significantly lower in the Ad-NASH group than in the SS and Ea-NASH groups. Portal venous TBF (PVTBF) was significantly lower in the Ea-NASH group than in the SS group, and PVTBF was lower in the Ad-NASH group than in the Ea-NASH group. Total hepatic TBF (THTBF) was significantly different between the SS and Ea-NASH groups and between the SS and Ad-NASH groups.

CONCLUSIONS

In conclusion, measurements of TBF and LV are useful for evaluating the pathophysiological progression of NASH. In addition, these measurements can facilitate the differential diagnosis of SS and Ea-NASH, which may not be distinguishable by other means.

Can NASH be diagnosed, graded, and staged noninvasively?

Nonalcoholic bland steatosis and nonalcoholic steatohepatitis (NASH) are stages in the spectrum of nonalcoholic fatty liver disease (NAFLD). NASH may progress to end-stage liver disease. Liver biopsy distinguishes between patients with NASH and no NASH and can stage fibrosis. Markers of hepatocyte apoptosis hold promise as noninvasive tests for NASH diagnosis. Several scoring systems that combine routine clinical and laboratory variables and some proprietary panels can assist in predicting fibrosis severity. Noninvasive imaging modalities are reasonably accurate available tools to determine severity of fibrosis in NAFLD, but none of them yet can replace liver biopsy.

Hepatic steatosis, GH deficiency and the effects of GH replacement: a Liverpool magnetic resonance spectroscopy study

OBJECTIVE

Non-alcoholic fatty liver disease (NAFLD) is reported to be more common in patients with GH deficiency (GHD) than in the general population. we aimed to determine: i) liver fat in patients with GHD compared with age and body mass index (BMI)-matched controls; and ii) effect of 6 months of GH replacement (GHR) on liver fat.

PARTICIPANTS AND METHODS

The study included 28 GHD patients and 24 controls. 12 patients were studied before and after 6 months of GHR. Anthropometry, liver enzymes and lipid profiles were measured, and body composition and intrahepatocellular lipid (IHCL) were determined by magnetic resonance imaging and spectroscopy.

RESULTS

Age and BMI (median (inter-quartile range)) of patients and controls were 52.6 (14) vs 52.6 (12) years (P=0.9) and 27.8 (24.7, 34.7) vs 27.9 (25.1, 32.1) kg/m(2) (P=0.9). IGF1 was lower in the patients (11.5 vs 16.0 nmol/l, P=0.002). There was no difference in liver transaminases, lipids or IHCL between patients and controls (2.8 (1.3, 8.6) vs 5.0 (1.5, 12.7), P=0.72), despite significantly higher visceral fat in GHD patients. Thirty-two percent of patients and 50% of controls had NAFLD (defined as IHCL >5.6%), and the relationship between IHCL and BMI was the same in each group. GHR significantly reduced abdominal subcutaneous and visceral fat in all patients; however, GHR did not reduce liver fat.

CONCLUSIONS

NAFLD is equally common in patients with GHD and matched controls. GHR is associated with a hierarchical reduction in fat deposition (fat loss: visceral > subcutaneous > liver). Further studies involving GHD patients with NAFLD are required to conclude the role of GHR in treating NAFLD.

Non-high-density lipoprotein cholesterol as a biomarker for nonalcoholic steatohepatitis

BACKGROUND & AIMS

There are no clinically available biomarkers for nonalcoholic steatohepatitis (NASH); differentiating between steatosis and NASH requires histologic evaluation. Noninvasive methods are needed to replace liver biopsy and its associated risks. Production of very low density lipoprotein (VLDL) contributes to the development of NASH and might be used to distinguish steatosis from NASH. However, it is not possible to measure levels of VLDL directly in the clinic. Non-high-density lipoprotein-cholesterol (non-HDL-C) encompasses all apolipoprotein-B-containing lipoproteins, including VLDL, and can be calculated from standard lipid panels without additional cost.

METHODS

We evaluated the ability of non-HDL-C to differentiate steatosis from NASH in a prospective study of 218 patients with suspected NASH (steatosis, n = 100 and NASH, n = 118).

RESULTS

Patients with NASH had a trend toward increased levels of non-HDL-C, compared with those with steatosis (P = .08). However, among subjects not on lipid-lowering medications, those with NASH had significantly higher levels of non-HDL-C (144.6 mg/dL) than those with steatosis (129.3 mg/dL; P = .025). This difference remained significant when adjusted for levels of cholesterol and triglycerides, indicating that the difference results from increased levels of apolipoprotein B including VLDL. These findings were validated in a cohort of 40 patients with steatosis or NASH who were not taking lipid-lowering agents. The NASH group had significantly higher levels of non-HDL-C than the steatosis group (162.8 vs 145.9 mg/dL; P = .04).

CONCLUSIONS

NASH is associated with significantly higher levels of non-HDL-C than steatosis in patients who do not take lipid-lowering agents. This low-cost biomarker could be used in noninvasive differentiation between steatosis and NASH.

Non-invasive Diagnosis of Fibrosis in Non-alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in developed as well as in developing countries. Its prevalence continues to rise currently affecting approximately 20-30% of adults and 10% of children in the United States. Non-alcoholic fatty liver disease represents a wide spectrum of conditions ranging from fatty liver, which in general follows a benign non-progressive clinical course, to non-alcoholic steatohepatitis (NASH), a more serious form of NAFLD that may progress to cirrhosis and end-stage liver disease. Liver biopsy remains the gold standard for evaluating the degree of hepatic necroinflammation and fibrosis; however, several non-invasive investigations, such as serum biomarkers, have been developed to establish the diagnosis and also to evaluate treatment response. There has been a substantial development of non-invasive risk scores, biomarker panels, and radiological modalities to identify at risk patients with NAFLD without recourse to liver biopsy on a routine basis. Examples include combination of serum markers like NAFLD fibrosis score (NFS), BARD score, fibrometer, FIB4, and non-invasive tools like fibroscan which assess fibrosis in patients with NAFLD. Other markers of fibrosis that have been evaluated include high-sensitivity C-reactive protein, plasma pentraxin 3, interleukin-6, and cytokeratin-18. This review focuses on the methods currently available in daily clinical practice in hepatology and touches briefly on the potential future markers under investigation.

Prevalence and associated metabolic factors of nonalcoholic fatty liver disease in the general population from 2009 to 2010 in Japan: a multicenter large retrospective study

BACKGROUND

The prevalence of nonalcoholic fatty liver disease (NAFLD) has been increasing. This study aimed to assess the recent prevalence of NAFLD and to predict the prevalence of nonalcoholic steatohepatitis (NASH) with liver fibrosis using established scoring systems in the general population.

METHODS

A cross-sectional study was conducted among 8352 subjects who received health checkups from 2009 to 2010 in three health centers in Japan. Subjects with an intake over 20 g of alcohol/day or with other chronic liver diseases were excluded. Fatty liver was detected by ultrasonography. The probability of NASH with advanced fibrosis was calculated according to the body mass index, age, ALT, and triglyceride (BAAT) and FIB-4 (based on age, aspartate aminotransferase and alanine aminotransferase levels, and platelet counts) indices.

RESULTS

A total of 5075 subjects were enrolled. The overall prevalence of NAFLD was 29.7%. There was a significant threefold difference in the mean prevalence between males (41.0%) and females (17.7%). This prevalence showed a linear increase with body mass index, triglycerides, and low-density lipoprotein cholesterol regardless of threshold values, even without obesity. The estimated prevalence of NASH according to the BAAT index ≥3 was 2.7%, and according to the FIB-4 index it was 1.9%.

CONCLUSIONS

The prevalence of NAFLD has increased in the general population, especially in males. There is a linear relationship between the prevalence of NAFLD and various metabolic parameters, even in nonobese subjects. The prevalence of NASH with advanced fibrosis is estimated to be considerably high in subjects with NAFLD.

Diagnosis of nonalcoholic fatty liver disease in children and adolescents: position paper of the ESPGHAN Hepatology Committee

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease in children and adolescents in the United States, and most probably also in the rest of the industrialized world.As the prevalence of NAFLD in childhood increases with the worldwide obesity epidemic, there is an urgent need for diagnostic standards that can be commonly used by pediatricians and hepatologists. To this end, we performed a PubMed search of the adult and pediatric literature on NAFLD diagnosis through May 2011 using Topics and/or relevant Authors as search words. According to the present literature, NAFLD is suspected based on the association of fatty liver combined with risk factors (mainly obesity), after the exclusion of other causes of liver disease. The reference but imperfect standard for confirming NAFLD is liver histology. The following surrogate markers are presently used to estimate degree of steatosis and liver fibrosis and risk of progression to end-stage liver disease: imaging by ultrasonography or magnetic resonance imaging, liver function tests, and serum markers of liver fibrosis.NAFLD should be suspected in all of the overweight or obese children and adolescents older than 3 years with increased waist circumference especially if there is a NAFLD history in relatives. The typical presentation, however, is in children ages 10 years and older. The first diagnostic step in these children should be abdominal ultrasound and liver function tests, followed by exclusion of other liver diseases. Overweight/obese children with normal ultrasonographic imaging and normal liver function tests should still be monitored due to the poor sensitivity of these tests at a single assessment.Indications for liver biopsy include the following: to rule out other treatable diseases, in cases of clinically suspected advanced liver disease, before pharmacological/surgical treatment, and as part of a structured intervention protocol or clinical research trial.

Noninvasive Parameters and hepatic fibrosis scores in children with nonalcoholic fatty liver disease

AIM: To evaluate the noninvasive parameters and hepatic fibrosis scores in obese children with nonalcoholic fatty liver disease (NAFLD).

METHODS: A total of 77 children diagnosed with NAFLD via liver biopsy were included and divided into 2 subgroups according to the histopathologic staging of hepatic fibrosis: mild (stage 0-1) vs significant fibrosis (stage 2-4). Clinical and laboratory parameters were evaluated in each patient. The aspartate aminotransferase (AST)/alanine aminotransferase (ALT) ratio, AST/platelet ratio index (APRI), PGA index, Forns index, FIB-4, NAFLD fibrosis score, and pediatric NAFLD fibrosis index (PNFI) were calculated.

RESULTS: No clinical or biochemical parameter exhibited a significant difference between patients with mild and significant fibrosis. Among noninvasive hepatic fibrosis scores, only APRI and FIB4 revealed a significant difference between patients with mild and significant fibrosis (APRI: 0.67 ± 0.54 vs 0.78 ± 0.38, P = 0.032 and FIB4: 0.24 ± 0.12 vs 0.31 ± 0.21, P = 0.010). The area under the receiving operating characteristic curve of FIB4 was 0.81, followed by Forns index (0.73), APRI (0.70), NAFLD fibrosis score (0.58), AST/ALT ratio (0.53), PGA score (0.45), and PNFI (0.41).

CONCLUSION: APRI and FIB4 might be useful noninvasive hepatic fibrosis scores for predicting hepatic fibrosis in children with NAFLD.

The association of HIV viral load with indirect markers of liver injury

This study assessed the association of HIV RNA with indirect markers of liver injury including FIB-4 index, liver enzymes and platelet counts in a high-risk Hispanic population. The data were derived from a prospective study that included 138 HIV/hepatitis C (HCV)-coinfected and 68 HIV-infected participants without hepatitis C or B co-infection (mono-infected). In unadjusted analyses, detectable HIV viral load (vs undetectable, <400 copies/mL) was associated with a 40% greater odds (OR 1.4, 95% CI: 1.1-1.9, P = 0.016) of FIB-4 > 1.45 in the HIV/HCV-coinfected group and 70% greater odds of FIB-4 > 1.45 (OR 1.7, 95% CI: 1.0-2.8; P = 0.046) in the HIV-mono-infected group. In multivariable analyses, a 1 log(10) increase in HIV RNA was associated with a median increase in FIB-4 of 12% in the HIV/HCV-coinfected group and 11% in the HIV-mono-infected group (P < 0.0001). Among the HIV/HCV-coinfected group, the elevating effect of HIV RNA on FIB-4 was strongest at low CD4 counts (P = 0.0037). Among the HIV-mono-infected group, the association between HIV RNA and FIB-4 was independent of CD4 cell counts. HIV RNA was associated with alterations in both liver enzymes and platelet counts. HIV antiretroviral therapy was not associated with any measure of liver injury examined. This study suggests that HIV may have direct, injurious effects on the liver and that HIV viral load should be considered when these indirect markers are used to assess liver function.

Validation of the FIB4 index in a Japanese nonalcoholic fatty liver disease population

BACKGROUND

A reliable and inexpensive noninvasive marker of hepatic fibrosis is required in patients with nonalcoholic fatty liver disease (NAFLD). FIB4 index (based on age, aspartate aminotransferase [AST] and alanine aminotransferase [ALT] levels, and platelet counts) is expected to be useful for evaluating hepatic fibrosis. We validated the performance of FIB4 index in a Japanese cohort with NAFLD.

METHODS

The areas under the receiver operating characteristic curves (AUROC) for FIB4 and six other markers were compared, based on data from 576 biopsy-proven NAFLD patients. Advanced fibrosis was defined as stage 3-4 fibrosis. FIB4 index was assessed as: age (yr) × AST (IU/L)/(platelet count (10(9)/L) × √ALT (IU/L)) RESULTS: Advanced fibrosis was found in 64 (11%) patients. The AUROC for FIB4 index was superior to those for the other scoring systems for differentiating between advanced and mild fibrosis. Only 6 of 308 patients with a FIB4 index below the proposed low cut-off point (< 1.45) were under-staged, giving a high negative predictive value of 98%. Twenty-eight of 59 patients with a FIB4 index above the high cut-off point (> 3.25) were over-staged, giving a low positive predictive value of 53%. Using these cutoffs, 91% of the 395 patients with FIB-4 values outside 1.45-3.25 would be correctly classified. Implementation of the FIB4 index in the Japanese population would avoid 58% of liver biopsies.

CONCLUSION

The FIB4 index was superior to other tested noninvasive markers of fibrosis in Japanese patients with NAFLD, with a high negative predictive value for excluding advanced fibrosis. The small number of cases of advanced fibrosis in this cohort meant that this study had limited power for validating the high cut-off point.

Non-invasive assessment of liver fibrosis

The presence and degree of hepatic fibrosis is crucial in order to make therapeutic decisions and predict clinical outcomes. Currently, the place of liver biopsy as the standard of reference for assessing liver fibrosis has been challenged by the increasing awareness of a number of drawbacks related to its use (invasiveness, sampling error, inter-/intraobserver variability). In parallel with this, noninvasive assessment of liver fibrosis has experienced explosive growth in recent years and a wide spectrum of noninvasive methods ranging from serum assays to imaging techniques have been developed. Some are validated methods, such as the Fibrotest/ Fibrosure and transient elastography in Europe, and are gaining a growing role in routine clinical practice, especially in chronic hepatitis C. Large-scale validation is awaited in the setting of other chronic liver diseases. However, noninvasive tests used to detect significant fibrosis and cirrhosis, the two major clinical endpoints, are not yet at a level of performance suitable for routine diagnostic tests, and there is still no perfect surrogate or method able to completely replace an optimal liver biopsy. This article aims to review current noninvasive tests for the assessment of liver fibrosis and the perspectives for their rational use in clinical practice.

Non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) refers to the accumulation of hepatic steatosis not due to excess alcohol consumption. The prevalence of NAFLD is up to 30% in developed countries and nearly 10% in developing nations, making NAFLD the most common liver condition in the world. The pathogenesis of NAFLD is related to insulin resistance and, thus, it is frequently found in individuals who have central obesity or diabetes. Insulin resistance and excess adiposity are associated with increased lipid influx into the liver and increased de novo hepatic lipogenesis, promoting hepatic triglyceride accumulation. Defects in lipid utilization via mitochondrial oxidation and lipid export may also contribute to hepatic lipid build-up. Adipocytokine alterations, lipotoxicity from saturated fatty acids and fructose have been all been implicated in causing hepatocyte injury in NAFLD through pathways involving oxidative and endoplasmic reticulum stress. Clinically, NAFLD is commonly asymptomatic and frequently detected incidentally by blood liver function tests or imaging performed for other reasons. Subjects with NAFLD have a higher mortality rate than the general population and are at increased risk of developing cardiovascular disease and diabetes in the future. Histologically, NAFLD occurs as a spectrum from mild hepatic steatosis only, to non-alcoholic steatohepatitis (NASH) characterized by hepatocellular injury and inflammation, to cirrhosis. A diagnosis of NASH with associated fibrosis heralds a more significant prognosis as it is more likely to progressive to cirrhosis with complications of hepatic failure and hepatocellular carcinoma. Currently, the diagnosis of NASH requires a liver biopsy, however, serum based markers of hepatocyte apoptosis such as cytokeratin-18 fragments offer promise as accurate non-invasive diagnostic tests. Treatment of NAFLD revolves around addressing concomitant metabolic risk factors and improving insulin resistance through weight loss measures and exercise. Insulin sensitizing agents such as pioglitazone and anti-oxidant agents such as vitamin E show some promise in improving liver histology in patients with NASH, however, the long-term benefit of these medications has not been demonstrated.

Advances in pediatric nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) has emerged as the most common cause of pediatric liver disease in the developed world. Children have a form of NAFLD that is pathologically distinct from adults. Although NAFLD remains a pathologic diagnosis, biomarkers and imaging studies hold promise as noninvasive means of both establishing the diagnosis and following the disease course. Significant advancements have recently been made in genetics, pathophysiology, and the treatment of NAFLD. The purpose of this article is to provide a clinically relevant review of pediatric NAFLD with an emphasis on recent developments in the field.

Platelet count for predicting fibrosis in nonalcoholic fatty liver disease

BACKGROUND

The severity of liver fibrosis is known to be a good indicator for surveillance, and for determining the prognosis and optimal treatment of nonalcoholic fatty liver disease (NAFLD). However, it is virtually impossible to carry out liver biopsies in all NAFLD patients. The purpose of this study was to investigate the clinical usefulness of measuring the platelet count for predicting the severity of liver fibrosis in a large retrospective cohort of Japanese patients with NAFLD.

METHODS

A total of 1,048 patients with liver-biopsy-confirmed NAFLD seen between 2002 and 2008 were enrolled from nine hepatology centers in Japan. Laboratory evaluations were performed for all patients.

RESULTS

A linear decrease of the platelet count with increasing histological severity of hepatic fibrosis was revealed. The area under the receiver operating characteristic curve estimating the diagnostic performance of the platelet count for hepatic fibrosis Stage 3 was 0.774 (optimal cutoff value, 19.2 × 10(4)/μl; sensitivity, 62.7%; specificity, 76.3%), and that for Stage 4 was 0.918 (optimal cutoff value, 15.3 × 10(4)/μl; sensitivity, 80.5%; specificity, 88.8%).

CONCLUSIONS

The platelet count may be an ideal biomarker of the severity of fibrosis in NAFLD patients, because it is simple, easy to measure and handle, cost-effective, and accurate for predicting the severity of fibrosis. Furthermore, by using the platelet count cutoff value validated in our multiple large trials, efficient recruitment of NAFLD patients may be facilitated.

Diagnosis and evaluation of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of elevated liver function tests results, after the commonly investigated causes have been excluded, and frequently coexists with type 2 diabetes mellitus (T2DM) because the conditions have common risk factors. As both T2DM and NAFLD are related to adverse outcomes of the other, diagnosis and valuation of fatty liver is an important part of the management of diabetes. Although noninvasive methods, such as biomarkers, panel markers, and imaging, may support a diagnostic evaluation of NAFLD patients, accurate histopathological findings cannot be achieved without a liver biopsy. As it is important to know whether steatohepatitis and liver fibrosis are present for the management of NAFLD, liver biopsy remains the gold standard for NAFLD diagnosis and evaluation. Therefore, new investigations of the pathogenesis of NAFLD are necessary to develop useful biomarkers that could provide a reliable noninvasive alternative to liver biopsy.

Complex non-invasive fibrosis models are more accurate than simple models in non-alcoholic fatty liver disease

BACKGROUND AND AIM

Significant hepatic fibrosis is prognostic of liver morbidity and mortality in non-alcoholic fatty liver disease (NAFLD); however, it remains unclear whether non-invasive fibrosis models can determine this end-point. We therefore compared the accuracy of simple bedside versus complex fibrosis models across a range of fibrosis in a multi-centre NAFLD cohort.

METHODS

Simple (APRI, BARD) and complex (Hepascore, Fibrotest, FIB4) fibrosis models were calculated in 242 NAFLD subjects undergoing liver biopsy. Significant (F2-4) and advanced fibrosis (F3,4) were defined using Kleiner criteria. Models were compared using area under the receiver operator characteristic curves (AUC). Cut-offs were determined by Youden Index or 90% predictive values.

RESULTS

For significant fibrosis, non-invasive fibrosis models had modest accuracy (AUC 0.707-0.743) with BARD being least accurate (AUC 0.609, P < 0.05 vs others). Using single cut-offs, sensitivities and predictive values were < 80%; using two cut-offs, > 75% of subjects fell within indeterminate ranges. Simple models had significantly more subjects within indeterminate ranges than complex models (99.1-100% vs 82.1-84.4% respectively, P < 0.05 for all). For advanced fibrosis, complex models were more accurate than BARD (AUC 0.802-0.858 vs 0.701, P < 0.05). Using two cut-offs, complex models had fewer individuals within indeterminate ranges than BARD (11.1-32.3% vs 70.7%, P < 0.01 for all). For cirrhosis, complex models had higher AUC values than simple models.

CONCLUSIONS

In NAFLD subjects, non-invasive models have modest accuracy for determining significant fibrosis and have predictive values less than 90% in the majority of subjects. Complex models are more accurate than simple bedside models across a range of fibrosis.

Non-alcoholic fatty liver disease (NAFLD): why you should care, when you should worry, what you should do

For the diabetologist, non-alcoholic fatty liver disease (NAFLD) is important at both ends of its spectrum. It is an early warning sign of future risk of metabolic syndrome, type 2 diabetes mellitus, and cardiovascular disease. It may also lead to late life-threatening sequela of diabetes mellitus in the event of progression to liver failure or hepatocellular carcinoma. This review will highlight the recent progress in understanding the natural history of non-alcoholic fatty liver disease and in developing a rational approach to its diagnosis, staging, and management. The pandemic prevalence of non-alcoholic fatty liver disease in Western countries necessitates both a high index of suspicion to identify cases and a non-invasive approach to staging, which is best achieved with clinical/biochemical panels and transient elastography. Lifestyle modification is the cornerstone of management. Recent clinical trials provide support for pharmacologic therapies directed at the metabolic syndrome and at protecting the liver but more data are needed. Bariatric surgery is appropriate for high-risk patients who fail conservative management. Patients with liver failure or hepatocellular carcinoma may be candidates for liver transplantation.

Biomarkers of liver fibrosis

Fibrosis prediction is an essential part of the assessment and management of patients with chronic liver disease. Blood-based biomarkers offer a number of advantages over the traditional standard of fibrosis assessment of liver biopsy, including safety, cost-savings and wide spread accessibility. Current biomarker algorithms include indirect surrogate measures of fibrosis, including aminotransaminases and platelet count, or direct measures of fibrinogenesis or fibrinolysis such as hyaluronic acid and tissue inhibitor of metalloproteinase-1. A number of algorithms have now been validated across a range of chronic liver disease including chronic viral hepatitis, alcoholic and non-alcoholic fatty liver disease. Furthermore, several models have been demonstrated to be dynamic to changes in fibrosis over time and are predictive of liver-related survival and overall survival to a greater degree than liver biopsy. Current limitations of biomarker models include a significant indeterminate range, and a predictive ability that is limited to only a few stages of fibrosis. Utilization of these biomarker models requires knowledge of patient co-morbidities which may produce false positive or negative results in a small proportion of individuals. Furthermore, knowledge of the underlying prevalence of fibrosis in the patient population is required for interpretation of the positive or negative predictive values of a test result. Novel proteins identified by proteomic technology and genetic polymorphisms from genome association studies offer the possibility for further refinement and individualization of biomarker fibrosis models in the future.

Invasive and non-invasive methods for the assessment of fibrosis and disease progression in chronic liver disease

Chronic liver diseases represent a major public health problem, accounting for significant morbidity and mortality worldwide. Their prognosis and management greatly depend on the amount and progression of liver fibrosis with the risk of developing cirrhosis. Liver biopsy, traditionally considered as the reference standard for staging of fibrosis, has been challenged over the past decade by the development of novel non invasive methodologies. These methods rely on two distinct but complementary approaches: i) a 'biological' approach based on the dosage of serum biomarkers of fibrosis; ii) a 'physical' approach based on the measurement of liver stiffness using transient elastography (TE). Non invasive methods have been initially studied and validated in chronic hepatitis C but are now increasingly used in other chronic liver diseases, resulting in a significant decrease in the need for liver biopsy. However, they will likely not completely abolish the need for liver biopsy and they should rather be employed as an integrated system with liver biopsy. This review is aimed at discussing the advantages and inconveniences of non invasive methods in comparison with liver biopsy for the management of patients with chronic liver diseases.

Performance of the aspartate aminotransferase-to-platelet ratio index for the staging of hepatitis C-related fibrosis: an updated meta-analysis

The aspartate aminotransferase-to-platelet ratio index (APRI), a tool with limited expense and widespread availability, is a promising noninvasive alternative to liver biopsy for detecting hepatic fibrosis. The objective of this study was to update the 2007 meta-analysis to systematically assess the accuracy of APRI in predicting significant fibrosis, severe fibrosis, and cirrhosis stage in hepatitis C virus (HCV) monoinfected and HCV / human immunodeficiency virus (HIV) coinfected individuals. Studies comparing APRI versus biopsy in HCV patients were identified via a thorough literature search. Areas under summary receiver operating characteristic curves (AUROC), sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were used to examine the APRI accuracy for the diagnosis of significant fibrosis, severe fibrosis, and cirrhosis. Heterogeneity was explored using meta-regression. Twenty-one additional studies were eligible for the update and, in total, 40 studies were included in this review (n = 8,739). The summary AUROC of the APRI for the diagnosis of significant fibrosis, severe fibrosis, and cirrhosis were 0.77, 0.80, and 0.83, respectively. For significant fibrosis, an APRI threshold of 0.7 was 77% sensitive and 72% specific. For severe fibrosis, a threshold of 1.0 was 61% sensitive and 64% specific. For cirrhosis, a threshold of 1.0 was 76% sensitive and 72% specific. Moreover, we found that the APRI was less accurate for the identification of significant fibrosis, severe fibrosis, and cirrhosis in HIV/HCV coinfected patients.

CONCLUSION

Our large meta-analysis suggests that APRI can identify hepatitis C-related fibrosis with a moderate degree of accuracy. Application of this index may decrease the need for staging liver biopsy specimens among chronic hepatitis C patients.

Systematic review: the diagnosis and staging of non-alcoholic fatty liver disease and non-alcoholic steatohepatitis

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) has become the most prevalent cause of liver disease in Western countries. The development of non-alcoholic steatohepatitis (NASH) and fibrosis identifies an at-risk group with increased risk of cardiovascular and liver-related deaths. The identification and management of this at-risk group remains a clinical challenge.

AIM

To perform a systematic review of the established and emerging strategies for the diagnosis and staging of NAFLD.

METHODS

Relevant research and review articles were identified by searching PubMed, MEDLINE and EMBASE.

RESULTS

There has been a substantial development of non-invasive risk scores, biomarker panels and radiological modalities to identify at-risk patients with NAFLD without recourse to liver biopsy on a routine basis. These modalities and algorithms have improved significantly in their diagnosis and staging of fibrosis and NASH in patients with NAFLD, and will likely impact on the number of patients undergoing liver biopsy.

CONCLUSIONS

Staging for NAFLD can now be performed by a combination of radiological and laboratory techniques, greatly reducing the requirement for invasive liver biopsy.

Nonalcoholic fatty liver disease across ethno-racial groups: do Asian-American adults represent a new at-risk population?

BACKGROUND AND AIM

Nonalcoholic fatty liver disease (NAFLD) is increasingly common worldwide. We explored clinical, laboratory, and histological features of NAFLD as well as risk factors for histologically advanced disease among under-represented ethno-racial groups.

METHODS

Patient records from one NAFLD clinic in California from 1998-2008 were reviewed. Biopsies were graded using Brunt criteria by a hepatopathologist blinded to clinical data. We used multivariate logistic regression to assess associations between ethno-racial group and histological severity of NAFLD, while controlling for other factors.

RESULTS

We identified 90 biopsy-proven cases of NAFLD. Mean age was 49 years (standard deviation [SD]= 11.6), and half were female. 52% of patients were Caucasian, 20% Latino-American, 18% Asian-American, and 10% Middle Eastern-American. There were significant differences among groups with respect to age, weight, body mass index (BMI), and grade of hepatic steatosis (all P < 0.05). In multivariate analysis, older age was associated with severe (Brunt ≥ 2) inflammation (odds ratio [OR] 1.1, P = 0.002) and severe (Brunt ≥ 3) fibrosis (OR 1.2, P = 0.001), diabetes was associated with severe inflammation (OR 3.18, P = 0.07) and severe fibrosis (OR 8.81, P = 0.002), and increased BMI was associated with severe fibrosis (OR 2.43, P = 0.07). Additionally, compared to Caucasians, Asian-Americans showed a trend toward an association with severe (Brunt > 2) steatosis (OR 3.83, P = 0.08) and severe inflammation (OR 5.42, P = 0.06).

CONCLUSIONS

The findings from this ethno-racially diverse clinic-based cohort are consistent with prior studies and also suggest that Asian-Americans may be at risk for advanced NAFLD. This may have implications for the prevention, evaluation, and treatment of patients with NAFLD that merit further study.

A combination of the pediatric NAFLD fibrosis index and enhanced liver fibrosis test identifies children with fibrosis

BACKGROUND & AIMS

Nonalcoholic fatty liver disease (NAFLD) encompasses diseases from simple steatosis, to steatohepatitis, to fibrosis, and cirrhosis. The pediatric NAFLD fibrosis index (PNFI) and the enhanced liver fibrosis (ELF) test are potential noninvasive markers for fibrosis. We prospectively evaluated the performance of PNFI and ELF in assessing fibrosis in children with biopsy-proven NAFLD.

METHODS

We analyzed 111 consecutive children with NAFLD. The stage of fibrosis was scored according to the Nonalcoholic Steatohepatitis Clinical Research Network. PNFI was calculated based on age, waist circumference, and levels of triglycerides. The ELF test was used to determine levels of hyaluronic acid, the amino-terminal propeptide of type III collagen, and tissue inhibitor of metalloproteinase-1.

RESULTS

Some degree of fibrosis was detected in 68.5% of patients (62 had stage 1, 5 had stage 2, and 9 had stage 3). PNFI and ELF test values was higher among patients with fibrosis (P < .001). The area under the receiver operating characteristic (ROC) curve for predicting fibrosis using the PNFI and ELF test was 0.761 and 0.924, respectively. The best performance was obtained by combining PNFI and ELF test with (area under the receiver operating characteristic curve = 0.944). The combined results from the PNFI and ELF test predicted the presence or absence of fibrosis in 86.4% of children with NAFLD.

CONCLUSIONS

In children with NAFLD, the combined results from the PNFI and ELF test can accurately assess the presence of liver fibrosis and identify patients that should be evaluated by liver biopsy.

Bioinformatics-driven identification and examination of candidate genes for non-alcoholic fatty liver disease

Objective

Candidate genes for non-alcoholic fatty liver disease (NAFLD) identified by a bioinformatics approach were examined for variant associations to quantitative traits of NAFLD-related phenotypes.

Research Design and Methods

By integrating public database text mining, trans-organism protein-protein interaction transferal, and information on liver protein expression a protein-protein interaction network was constructed and from this a smaller isolated interactome was identified. Five genes from this interactome were selected for genetic analysis. Twenty-one tag single-nucleotide polymorphisms (SNPs) which captured all common variation in these genes were genotyped in 10,196 Danes, and analyzed for association with NAFLD-related quantitative traits, type 2 diabetes (T2D), central obesity, and WHO-defined metabolic syndrome (MetS).

Results

273 genes were included in the protein-protein interaction analysis and EHHADH, ECHS1, HADHA, HADHB, and ACADL were selected for further examination. A total of 10 nominal statistical significant associations (P<0.05) to quantitative metabolic traits were identified. Also, the case-control study showed associations between variation in the five genes and T2D, central obesity, and MetS, respectively. Bonferroni adjustments for multiple testing negated all associations.

Conclusions

Using a bioinformatics approach we identified five candidate genes for NAFLD. However, we failed to provide evidence of associations with major effects between SNPs in these five genes and NAFLD-related quantitative traits, T2D, central obesity, and MetS.

Nonalcoholic fatty liver in Asia: Firmly entrenched and rapidly gaining ground

Nonalcoholic fatty liver disease (NAFLD) is becoming an important chronic liver disorder in Asia. Prevalence figures show regional variations but at least 10% of the general population in Asia have fatty liver. Fatty liver can develop with relatively small changes in weight (2-3 kg), often with increasing central adiposity. The metabolic syndrome may precede or follow NAFLD. Overt diabetes is present in one-third of cases but when oral glucose tolerance tests are performed, a further third of individuals have impaired glucose tolerance or diabetes. Natural history data are still scarce but cases of advanced hepatic fibrosis and hepatocellular carcinoma are now regularly reported. Many cases of cryptogenic cirrhosis are also attributable to NAFLD. Histological progression has been demonstrated for patients with NASH as well as for those with hepatic steatosis alone. Genetic factors may in part contribute to the rise in NAFLD. Polymorphisms within apolipoprotein C3 (APOC3) gene have been linked to NAFLD in lean Indian men. Although a number of other polymorphisms involving genes controlling adipose distribution, insulin signalling, adipokine responses and hepatic fibrosis have been reported, these studies have been underpowered. Transient elastography could help in detecting and monitoring hepatic fibrosis but further refinements in technique are necessary for obese individuals. Of the biomarkers, hyaluronic acid and cytokeratin-18 fragment testing show promise as markers of hepatic fibrosis and NASH, respectively. Lifestyle alterations including dietary changes and increased physical activity remain the cornerstone of management. Attention should be paid to prevention through public education of campaigns addressing the increase in both adult and childhood obesity.

The Finnish Diabetes Risk Score (FINDRISC) as a screening tool for hepatic steatosis

INTRODUCTION. Hepatic steatosis due to non-alcoholic fatty liver disease is associated with obesity, dyslipidemia, insulin resistance, and type 2 diabetes. The Finnish Diabetes Risk Score (FINDRISC) is a prognostic screening tool to detect people at risk for type 2 diabetes without the use of any blood test. The objective of this study was to evaluate whether FINDRISC can also be used to screen for the presence of hepatic steatosis. PATIENTS AND METHODS. Steatosis was determined by ultrasound. The study sample consisted of 821 non-diabetic subjects without previous hepatic disease; 81% were men (mean age 45 ± 9 years) and 19% women (mean age 41 ± 10 years). RESULTS. Steatosis was present in 44% of men and 10% of women. The odds ratio for one unit increase in the FINDRISC associated with the risk of steatosis was 1.30 (95% CI 1.25-1.35), similar for men and women. The area under the receiver operating characteristics curve for steatosis was 0.80 (95% CI 0.77-0.83); 0.80 in men (95% CI 0.77-0.83) and 0.83 (95% CI 0.73-0.93) in women. CONCLUSIONS. Our data suggest that the FINDRISC could be a useful primary screening tool for the presence of steatosis.

Validation of P2/MS for reflecting hepatic fibrosis in patients with hepatocellular carcinoma

BACKGROUND/AIMS

P2/MS is known as a simple, accurate, and noninvasive marker for determination of the degree of hepatic fibrosis in patients with viral hepatitis. We aimed to validate P2/MS in patients with HCC.

METHODS

Consecutive HCC patients who underwent surgical resection between June 2007 and March 2009 at Seoul National University Hospital were enrolled. Fibrosis stage was reviewed and assessed according to METAVIR scoring. P2/MS values [platelet count (10(9)/L)](2)/[monocyte fraction (%)(x)segmented neutrophil fraction (%)] and other noninvasive fibrosis scoring systems were calculated.

RESULTS

A total of 171 patients were included; seven patients with METAVIR F1, 31 with F2, 41 with F3, and 92 with F4. The area under the receiver-operating characteristic curve of P2/MS was 0.804 [95% confidence interval (CI), 0.681~0.927] for detection of significant fibrosis (F2-F4) and 0.769 (95% CI, 0.698~0.839) for detection of histological cirrhosis (F4). At a value < 62, P2/MS detected significant fibrosis with a specificity of 85.7% (95% CI, 42.0~99.2) and a positive likelihood ratio of 4.268 (95% CI, 0.692~26.309); and at a value > 115, P2/MS ruled out significant fibrosis with a sensitivity of 90.2% (95% CI, 84.4~94.1) and a negative likelihood ratio of 0.34 (95% CI, 0.106~0.095). P2/MS had a superior efficacy for detection of hepatic fibrosis in patients with HCC compared to the other noninvasive panels.

CONCLUSIONS

P2/MS can accurately detect fibrosis in patients with HCC. Thus, P2/MS might be utilized as a noninvasive index reflecting the degree of hepatic fibrosis in HCC patients.

Current status and agenda in the diagnosis of nonalcoholic steatohepatitis in Japan

Nonalcoholic fatty liver disease (NAFLD), a manifestation of metabolic syndrome, includes a wide range of clinical entities from simple fatty liver, a benign condition, to nonalcoholic steatohepatitis (NASH), a condition which can progress to cirrhosis, hepatocellular carcinoma and hepatic failure. The diagnosis of NASH requires no history of previous or current significant alcohol consumption and no evidence of other chronic liver diseases. Ethanol intake levels of 20 g daily (or 140 g weekly) are endorsed as the acceptable threshold to define nonalcoholic patients. Liver biopsy is the current gold standard for the diagnosis of NASH and provides prognostic information. Histopathological diagnosis of NASH is based on the following 3 features: (1) hepatic macrovesicular steatosis; (2) lobular inflammation; and (3) ballooning degeneration of hepatocytes. It is impractical to biopsy every patient with suspected NAFLD. Although highly accurate and affordable noninvasive screening tools can differentiate NASH from NAFLD, no imaging studies or laboratory tests are able to precisely diagnose NASH. There is no universal agreement regarding the indications for liver biopsy in NAFLD patients. In Japan, liver biopsies are considered in patients with suspected NAFLD based on several criteria including low platelet counts, elevated fibrosis markers, increasing age and other deciding parameters. Further studies are needed to establish a suitable scoring system that can distinguish steatohepatitis from simple steatosis.

Non-invasive assessment of liver fibrosis: it is time for laboratory medicine

Chronic liver diseases (CLDs) represent a major cause of morbidity and mortality worldwide. In all etiologies of CLDs, staging of liver fibrosis is essential for both prognosis and management. Until a few years ago, liver biopsy was the only tool for the diagnosis of liver fibrosis in patients with CLDs. However, liver biopsy is an invasive and costly procedure. More recently, various serum biomarkers and laboratory tests have been proposed as surrogates of liver histology. Due to inadequate diagnostic accuracy or to lack of sufficient validation, guidelines still do not recommend them as a substitute for liver biopsy that is still considered the gold standard for the diagnosis of liver fibrosis. Notably, non-invasive serum biomarkers, when combined, may reduce by 50%-80% the number of liver biopsies needed for correctly classifying hepatic fibrosis. However, liver biopsy cannot be avoided completely, but should be used in those cases in which non-invasive methods show poor accuracy. In this view, serum biomarkers and liver biopsy represent a union between laboratory medicine and hepatology.

Clinical, laboratory and histological associations in adults with nonalcoholic fatty liver disease

The Nonalcoholic Steatohepatitis Clinical Research Network (NASH CRN) was formed to conduct multicenter studies on the etiology, contributing factors, natural history, and treatment of nonalcoholic steatohepatitis (NASH). The aim of this study was to determine the associations of readily available demographic, clinical, and laboratory variables with the diagnosis of NASH and its key histological features, and determine the ability of these variables to predict the severity of nonalcoholic fatty liver disease (NAFLD). A total of 1266 adults were enrolled in NASH CRN studies between October 2004 and February 2008, of whom 1101 had available liver histology. The median age was 50 years; 82% were white and 12% Hispanic. The median body mass index was 33 kg/m(2); 49% had hypertension and 31% had type 2 diabetes. On liver biopsy, 57% were judged to have definite NASH and 31% bridging fibrosis or cirrhosis. Using data from the 698 patients with liver biopsies within 6 months of clinical data, patients with definite NASH were more likely to be female and have diabetes, higher levels of aspartate and alanine aminotransferases, alkaline phosphatase, gamma glutamyl transpeptidase, and homeostasis model assessment of insulin resistance (HOMA-IR). Progressive models for predicting histological diagnoses performed modestly for predicting steatohepatitis or ballooning (area under receiver operating characteristic curves [AUROC] ranged from 0.70-0.79), and better for advanced fibrosis (AUROC 0.73-0.85).

CONCLUSION

Readily available clinical and laboratory variables can predict advanced fibrosis in adults with NAFLD, but additional information is needed to reliably predict the presence and severity of NASH. Prospective studies of this well-characterized population and associated tissue bank samples offer a unique opportunity to better understand the cause and natural history of NAFLD and develop more precise means for noninvasive diagnosis.

Validation of the BARD scoring system in Polish patients with nonalcoholic fatty liver disease (NAFLD)

Abtract

Noninvasive tools to assess liver disease

PURPOSE OF REVIEW

Improved understanding of the pathophysiology of fibrosis and recent technological advances have resulted in the development of several serum biomarkers and imaging tools as noninvasive alternatives to biopsy. This review highlights some of the recent advances and potential application of these tools in clinical practice.

RECENT FINDINGS

Several newer approaches have been used to improve the semiquantitative histological assessment of fibrosis in relation to biomarker development. These include statistical considerations, smooth muscle actin morphometry, and emerging microscopy techniques to quantify fibrillar collagen. Serum marker panels, initially developed for determining disease stage in chronic hepatitis C infection, have now been adapted for use in nonalcoholic fatty liver disease. Genetic markers of disease progression have been validated, and newer proteomic technologies are increasingly being applied towards biomarker discovery. A sequential approach or the combination of serum markers and transient elastography is able to significantly reduce the need for biopsy for the diagnosis of cirrhosis. Serum markers also appear to provide useful prognostic information in end-stage liver disease. Newer imaging methods and breath tests require further validation, but appear promising adjunctive techniques for prediction of advanced stage fibrosis and providing functional assessment.

SUMMARY

Current noninvasive tools have potential diagnostic and prognostic utility for end-stage liver disease. Adapting these methods into clinical practice remains a challenge.

Recent advances in nonalcoholic fatty liver disease

PURPOSE OF REVIEW

This review focuses on recent advances in the study of the epidemiology, pathogenesis, natural history and treatment of nonalcoholic fatty liver disease (NAFLD).

RECENT FINDINGS

Study of hepatic lipid metabolism, insulin resistance, mitochondrial dysfunction and oxidative stress, genetic variants and predisposition to altered metabolism and cell injury have contributed to our current understanding of NAFLD. Differential expression of microRNA in fatty liver and its implication in disease pathogenesis and therapeutic potential have continued to advance over the year. The pathogenesis of hepatocellular carcinoma in steatohepatitis continues to be explored. The diagnostic utility of imaging and noninvasive markers seems promising in estimating the severity of steatosis and fibrosis. Liver biopsy remains the gold standard for accurately assessing NAFLD and steatohepatitis. Lifestyle modification and weight loss improve both metabolic profile and liver histology. Pharmacotherapy for the treatment of NAFLD remains lacking.

SUMMARY

The underlying mechanism and pathogenesis of NAFLD remain elusive despite ongoing researches to make significant advances in the understanding of its natural history, pathogenesis and management. Pharmacotherapy has yet to indicate a promising therapeutic intervention. Current treatment focuses on managing underlying cardio-metabolic risks.

Pathology of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is a significant complication of obesity and is recognized as the hepatic manifestation of the metabolic syndrome. The process occurs in adults and children and is characterized by the presence of increased amounts of fat in the liver (steatosis). With inflammation, cell death and scarring (fibrosis), the process may result in end-stage liver disease, or be a precursor for hepatocellular carcinoma. Excess hepatic fat is now recognized as an independent marker for increased cardiovascular risk. Even though imaging studies and laboratory-based tests are accurate at detecting significant steatosis and/or advanced fibrosis, respectively, the diagnosis and characterization of NAFLD ultimately depend on histopathologic evaluation, as the parenchymal alterations that comprise the spectrum of injury in NAFLD include patterns as well as specific lesions. Histologic findings in children may differ from those in adults. In this Review, the histologic features that are diagnostic and discriminatory between steatosis and steatohepatitis, the significance of the distinction between steatosis and steatohepatitis, the types and locations of fibrosis, and the histologic variances between adult and pediatric NAFLD are discussed. Clinical advantages as well as potential drawbacks of liver biopsy are presented. Current pathophysiologic concepts relevant to histologic findings are discussed.

Diagnosis of fibrosis and cirrhosis using liver stiffness measurement in nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is one of the most common liver diseases in affluent countries. Accurate noninvasive tests for liver injury are urgently needed. The aim of this study was to evaluate the accuracy of transient elastography for the diagnosis of fibrosis and cirrhosis in patients with NAFLD and to study factors associated with discordance between transient elastography and histology. Two hundred forty-six consecutive patients from two ethnic groups had successful liver stiffness measurement and satisfactory liver biopsy specimens. The area under the receiver-operating characteristics curve (AUROC) of transient elastography for F3 or higher and F4 disease was 0.93 and 0.95, respectively, and was significantly higher than that of the aspartate aminotransferase-to-alanine aminotransferase ratio, aspartate aminotransferase-to-platelet ratio index, FIB-4, BARD, and NAFLD fibrosis scores (AUROC ranged from 0.62 to 0.81, P < 0.05 for all comparisons). At a cutoff value of 7.9 kPa, the sensitivity, specificity, and positive and negative predictive values for F3 or greater disease were 91%, 75%, 52%, and 97%, respectively. Liver stiffness was not affected by hepatic steatosis, necroinflammation, or body mass index. Discordance of at least two stages between transient elastography and histology was observed in 33 (13.4%) patients. By multivariate analysis, liver biopsy length less than 20 mm and F0-2 disease were associated with discordance.

CONCLUSION

Transient elastography is accurate in most NAFLD patients. Unsatisfactory liver biopsy specimens rather than transient elastography technique account for most cases of discordance. With high negative predictive value and modest positive predictive value, transient elastography is useful as a screening test to exclude advanced fibrosis. Liver biopsy may be considered in NAFLD patients with liver stiffness of at least 7.9 kPa.