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Background
Serum Markers of Hepatic Fibrosis:
Biochemical marker combinations are being developed as alternatives to liver biopsy in patients with chronic hepatitis C and other chronic liver diseases, including chronic hepatitis B, alcoholic liver disease, or non-alcoholic steatosis. Non-invasive tests are being developed to replace liver biopsy, and thus avoid the risk of biopsy-related adverse events. Non-invasive tests also have the potential to avoid limitations of liver biopsy, including the risk of sampling errors and inter- and intra-pathologist variability.
The FibroSpect II (Prometheus Laboratories, San Diego, CA) is a non-invasive diagnostic panel to assist in the detection of liver fibrosis. The FibroSpect II uses a combination of components in the fibrogenic cascade, such as hyaluronic acid, TIMP-1 (tissue inhibitor of metalloproteinase), and alpha-2-macroglobulin. The test is intended to differentiate mild fibrosis from more severe disease. The manufacturer's website provides "performance data" on the FibroSpect II Test, but this information is unpublished.
The FibroTest (Biopredictive, Houilles, France) and the ActiTest (Biopredictive, Houilles, France), marketed in the United States as the HCV-FibroSure Test (LabCorp, Burlington, NC), are the most thoroughly studied serum biochemical test for the assessment of fibrosis and necroinflammatory activity, respectively. The HCV-FibroSure Test includes the following five markers, as well as age and gender: alpha2-macroglobulin, haptoglobin, gamma-glutamyl transpeptidase (GGT), total bilirubin, apolipoprotein A1, plus alanine aminotransferase (ALT). Rossi et al (2003) reported on the results of FibroTest scores of 125 patients with hepatitis C. Of these, 57 had FibroTest scores either less than 0.1 (indicating no fibrosis) or greater than 0.6 (indicating significant fibrosis). Although 33 of the 125 patients had FibroTest scores of less than 0.1 and were therefore deemed unlikely to have fibrosis, 6 (18 %) had significant fibrosis. Conversely, of the 24 patients with scores of greater than 0.6 who were likely to have significant fibrosis, 5 (21 %) had mild fibrosis. The investigators concluded that, "[o]f the 125 patients in the cohort, 57 (46 %) could have avoided liver biopsy"; but discrepant results were recorded in 11 of those 57 (19 %). In other words, discrepancies with the biopsy gold standard were found in one-fifth of patients. There are no prospective clinical outcome studies of the HCV-FibroSure in the management of patients with hepatitis C or other chronic liver diseases.
An National Institutes of Health Consensus Statement on Management of Hepatitis C (NIH, 2002) concluded that liver biopsy is useful in defining baseline abnormalities of liver disease and in enabling patients and healthcare providers to reach a decision regarding antiviral therapy. The NIH Consensus Statement concludes that noninvasive tests are not adequate substitutes for liver biopsy.
Various noninvasive tests of hepatic fibrosis have been examined for monitoring patients with chronic hepatitis C virus (HCV) infection. These include routinely available laboratory tests, such as liver- associated chemistries, platelet count, and prothrombin time, as well as specific serum markers of fibrosis and inflammation not currently widely available or well validated. No single test or panel of serologic markers can provide an accurate assessment of intermediate stages of hepatic fibrosis. Similarly, quantitative tests of liver function and radiologic imaging of the liver are sensitive for diagnosing advanced cirrhosis but are not useful in assessing hepatic fibrosis and early cirrhosis.
In a review on newer markers for hepatocellular carcinoma, Marrero and Lok (2004) stated that there is a scarcity of longitudinal studies evaluating the ability of biomarkers to detect pre-clinical disease. There is an urgent need for novel biomarkers for the detection of early hepatocellular carcinoma.
Suzuki et al (2005) stated that “use of an accurate serum marker for severe hepatic fibrosis may also improve accuracy of non-invasive diagnostic models. Hyaluronic acid, a serum marker for severe hepatic fibrosis, has been reported to have a high diagnostic performance in assessing the severity of hepatic fibrosis in patients with alcoholic liver disease. In this issue, a non-invasive diagnostic model including hyaluronic acid was shown to have excellent performance in excluding the presence of medium to large esophageal varices in severe alcohol abusers. Based on current evidence, the strategy of using a non-invasive diagnostic model together with a serum marker for severe hepatic fibrosis may improve cost-benefit in the prevention of variceal hemorrhage among patients with alcoholic liver disease. The independent verification of such diagnostic models is needed”.
Evidence based guidelines on the management of hepatitis C from the American Association for the Study of Liver Diseases (Strader et al, 2004) stated: "Although liver fibrosis markers are commercially available, they are currently insufficiently accurate to support their routine use. Until sensitive serum markers can be developed that will define all stages of fibrosis and mirror the information derived from liver biopsy, the procedure remains the only means of defining the severity of damage from HCV infection in many patients".
Serum gamma glutamyltransferase (GGT) is elevated in individuals with acute and chronic alcohol toxicity. Serum GGT assay may be useful in evaluating patients when heavy drinking is suspected but the patient denies it (NIAAA, 2005).
Wilson et al (2006) stated that although most HCV infections are acquired by injection drug use, prospective data on the progression of liver fibrosis are sparse. In this study, baseline liver biopsies were obtained on a random sample of 210 out of 1,667 HCV-positive injection drug users (IDUs). Subjects were followed biannually, with a second biopsy offered to those eligible. Paired biopsies were scored 0 to 6 (modified Ishak score), significant fibrosis was defined as score 3 or greater, and progression of fibrosis was defined as an increase 2 or more units or clinical evidence of end-stage liver disease. Predictive values of blood markers (FibroSure, aspartate aminotransferase-to-platelet-ratio index (APRI) and alanine aminotransferase (ALT)) were assessed for detection of contemporaneous and future liver fibrosis. Among 119 prospectively followed IDUs, 96 % were African American; 97 % HCV genotype 1a/b; 27 % HIV-infected, and median age was 42 years. Most (90.7 %) did not have significant liver fibrosis at first biopsy. Although predictive value for detecting insignificant fibrosis at first biopsy was greater than 95 % for FibroSure, APRI, and ALT, specificities were 88.9 %, 72.7 %, and 72.7 %, respectively. After 4.2 years median follow-up, 21 % had progression of fibrosis, which was significantly associated with serum level of HCV RNA and ALT. No serological test had predictive value greater than 40 % for contemporaneous or future significant fibrosis. Even initial biopsy result had only a 30.4 % value for predicting future significant fibrosis. The authors concluded that significant liver fibrosis and progression were detected in some, but not most, IDUs in this cohort. In this setting with low fibrosis prevalence, FibroSure, ALT, and APRI tests predict insignificant fibrosis; however, further work is needed to find non-invasive markers of significant liver fibrosis.
Nourani and Pockros (2007) noted that biochemical markers are a potentially useful alternative to liver biopsy in patients with chronic hepatitis C aged 65 years and older. Furthermore, Rossi et al (2007) stated that an obstacle to widespread adoption of serum marker models (e.g., FibroSpect) for assessing liver fibrosis has been the lack of uniform performance indicators, such as diagnostic odds ratios and likelihood ratios. At present, serum marker models are not considered sufficiently reliable to replace liver biopsy in patients with chronic liver disease.
Shaheen and Myers (2008) performed a systematic review and meta-analysis of the diagnostic accuracy of fibrosis marker panels in patients with HIV/hepatitis C coinfection. Random effects meta-analyses and areas under summary receiver operating characteristics curves (AUC) examined test accuracy for detecting significant fibrosis (F2 to F4) and cirrhosis. Heterogeneity was explored using meta-regression. Five studies (n = 574) including 4 fibrosis measures (APRI [n = 4 studies], Forns' [n = 2], FibroTest [n = 1], SHASTA [n = 1]) met the inclusion criteria. The prevalence of significant fibrosis and cirrhosis were 51 % and 16 %, respectively. For the prediction of significant fibrosis, the summary AUC was 0.82 (95 % confidence interval [CI]: 0.78 to 86) and diagnostic odds ratio was 7.8 (5.1 to 11.9). For cirrhosis, these figures were 0.83 (0.69 to 0.97) and 11.0 (4.6 to 26.2), respectively. Meta-regression including study factors (methodological quality and biopsy adequacy), patient characteristics (age, gender, CD4 count), and fibrosis measure failed to identify important predictors of accuracy. The authors concluded that available fibrosis marker panels have acceptable performance for identifying significant fibrosis and cirrhosis in HIV/HCV-coinfected patients but are not yet adequate to replace liver biopsy. They noted that additional studies are needed to identify the optimal measure.
Smith and Sterling (2009) reviewed non-invasive measures and their ability to replace biopsy for assessing hepatic fibrosis in patients with chronic HCV. A systematic review of PUBMED and EMBASE was carried out through 2008 using the following search terms: HCV, liver, elastography, hepatitis, Fibroscan, SPECT, non-invasive liver fibrosis, ultrasonography, Doppler, MRI, Fibrotest, Fibrosure, Actitest, APRI, Forns and breath tests, alone or in combination. These investigators identified 151 studies: 87 using biochemical, 57 imaging and 7 breath tests either alone or in combination. The authors concluded that great strides are being made in the development of accurate non-invasive methods for determination of fibrosis. Although no single non-invasive test or model developed to date can match that information obtained from actual histology (i.e., inflammation, fibrosis, steatosis), combinations of 2 modalities of non-invasive methods can reliably differentiate between minimal and significant fibrosis, and thereby avoid liver biopsy in a significant percentage of patients.
Carlson and colleagues (2009) evaluated the clinical and economic outcomes of non-invasive testing strategies in the diagnosis of significant liver fibrosis (Metavir score greater than or equal to 2) compared with liver biopsy. These researchers developed a decision analytic model of non-invasive testing strategies in a hypothetical patient population with genotype 1 hepatitis C virus infection, with no contraindications to liver biopsy. The testing strategies included a testing algorithm using the Fibrosure test, a non-invasive measure of fibrosis, followed by liver biopsy for patients with indeterminate results, Fibrospect II, and Fibroscan. The primary outcomes were sensitivity, specificity, diagnostic accuracy (true positive + true negatives/total patients), and costs, evaluated from the health-care payer perspective. The testing algorithm using Fibrosure was the most accurate non-invasive strategy with a sensitivity, specificity, and overall accuracy of 84 %, 87 %, and 86 %, respectively. In comparison with liver biopsy alone, there was a cost savings of approximately $770/person with the Fibrosure testing algorithm, but a net decrease in accuracy of 14 %. Fibrospect II and Fibroscan had poorer accuracy (decreases of 12 % and 4 %, respectively) and lower costs (-$138 and -$357, respectively) compared with the Fibrosure algorithm. In uncertainty analyses in which biopsy sampling error was considered, the Fibrosure algorithm remained consistently less accurate (5 to 14 % decrease). The authors concluded that the results of this study suggested that compared with liver biopsy, non-invasive testing algorithms can result in short-term cost savings, but the consequences of misdiagnosis in terms of health outcomes and treatment costs might out-weigh the short-term gains in cost and convenience.
Adams (2011) stated that fibrosis prediction is an essential part of the management of patients with chronic liver disease. Serum 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.
Sebastiani and associates (2011) examined the effect of etiology and stages of hepatic fibrosis on the performance of fibrosis biomarkers. A total of 2,411 patients with compensated chronic liver disease (CLD) (hepatitis C virus [HCV] = 75.1 %, hepatitis B virus [HBV] = 10.5 %, non-alcoholic steato-hepatitis [NASH] = 7.9 %, HIV/HCV = 6.5 %) were consecutively enrolled in 9 centers. APRI, Forns'index, Lok index, AST-to-ALT ratio, Fib-4, platelets and Fibrotest-Fibrosure were tested against liver biopsy, considered the gold standard. The effect of the stages of hepatic fibrosis to diagnose significant fibrosis and cirrhosis (greater than or equal to F2 and F4, respectively) was investigated through difference between advanced and non-advanced fibrosis stages (DANA). Performance was expressed as observed area under the ROC curve (ObAUROC) and AUROC adjusted for DANA (AdjAUROC). Performance of APRI and Fibrotest-Fibrosure was higher than other biomarkers. In all etiologies, AdjAUROC was higher than ObAUROC. APRI showed its best performance in HCV mono-infected cases, with an AdjAUROC of 0.77 and 0.83 for greater than or equal to F2 and F4, respectively. In HBV and NASH patients, its performance was poor (AdjAUROC < 0.70). Performance of Fibrotest-Fibrosure was good in all etiologies for both greater than or equal to F2 and F4 (AdjAUROC > 0.73), except for greater than or equal to F2 in NASH (AdjAUROC = 0.64). Performance of all biomarkers was reduced in HCV cases with normal ALT. The authors concluded that etiology is a major factor influencing the performance of liver fibrosis biomarkers. Even after correction for DANA, APRI and Fibrotest-Fibrosure exhibit the best performance. However, liver biopsy is not replaceable, especially to diagnose greater than or equal to F2 and in HCV carriers with normal ALT.
Transient Elastography:
Transient elastography (FibroScan) is a rapid, non-invasive, bedside method to evaluate liver fibrosis by measuring liver stiffness. This device is based on 1-dimensional transient elastography, a technique that uses both ultrasound (5 MHz) and low-frequency (50 Hz) elastic waves, whose propagation velocity is directly related to elasticity. In cirrhotic patients, liver stiffness measurements range from 12.5 to 75.5 kPa (kPa). However, the clinical relevance of these values is unknown.
In a prospective study, de Ledinghen et al (2006) evaluated the accuracy of liver stiffness measurement for the detection of fibrosis and cirrhosis in HIV/hepatitis C virus (HCV)-coinfected patients and compared its accuracy with other non-invasive methods. These researchers studied 72 consecutive HIV patients with chronic hepatitis C who had a simultaneous liver biopsy and liver stiffness measurement by transient elastography (FibroScan; Echosens, Paris, France) for the assessment of liver fibrosis. Liver stiffness values ranged from 3.0 to 46.4 kPa. Liver stiffness was significantly correlated to fibrosis stage (Kendall tau-b = 0.48; p < 0.0001). The area under the receiver operating characteristic (AUROC) curve of liver stiffness measurement was 0.72 for F > or = 2 and 0.97 for F = 4. For the diagnosis of cirrhosis, AUROC curves of liver stiffness measurement were significantly higher than those for platelet count (p = 0.02), aspartate aminotransferase/ALT ratio (p = 0.0001), Aspartate aminotransferase-to-Platelet Ratio Index (p = 0.01), and FIB-4 (p = 0.004). The authors concluded that liver stiffness measurement is a promising noninvasive method for the assessment of fibrosis in HIV-infected patients with chronic HCV infection. They also noted that its use for the follow-up of these patients should be further evaluated.
Foucher and colleagues (2006) assessed the accuracy of FibroScan for the detection of cirrhosis in patients with chronic liver disease. A total of 711 patients with chronic liver disease were studied. Etiologies of chronic liver diseases were hepatitis C virus or hepatitis B virus infection, alcohol, non-alcoholic steatohepatitis, other, or a combination of the above etiologies. Liver fibrosis was evaluated according to the METAVIR score. Stiffness was significantly correlated with fibrosis stage (r = 0.73, p < 0.0001). Areas under the receiver operating characteristic curve (95 % CI) were 0.80 (0.75 to 0.84) for patients with significant fibrosis (F > 2), 0.90 (0.86 to 0.93) for patients with severe fibrosis (F3), and 0.96 (0.94 to 0.98) for patients with cirrhosis. Using a cut off value of 17.6 kPa, patients with cirrhosis were detected with a positive predictive value and a negative predictive value (NPV) of 90 %. Liver stiffness was significantly correlated with clinical, biological, and morphological parameters of liver disease. With an NPV greater than 90 %, the cut off values for the presence of esophageal varices stage 2/3, cirrhosis Child-Pugh B or C, past history of ascites, hepatocellular carcinoma, and esophageal bleeding were 27.5, 37.5, 49.1, 53.7, and 62.7 kPa, respectively. The authors concluded that FibroScan is a promising non-invasive method for detection of cirrhosis in patients with chronic liver disease. They noted that its use for the follow-up and management of these patients could be of great interest and should be evaluated further.
Corpechot and associates (2006) assessed the diagnostic performance of liver stiffness measurement (LSM) for the determination of fibrosis stage in chronic cholestatic diseases. A total of 101 patients with primary biliary cirrhosis (PBC, n = 73) or primary sclerosing cholangitis (PSC, n = 28) were prospectively enrolled in a multi-center study. All patients underwent liver biopsy (LB) and LSM. Histological and fibrosis stages were assessed on LB by two pathologists. LSM was performed by FibroScan. Efficiency of LSM for the determination of histological and fibrosis stages were determined by a ROC curve analysis. Analysis failed in 6 patients (5.9 %) because of unsuitable LB (n = 4) or LSM (n = 2). Stiffness values ranged from 2.8 to 69.1 kPa (median of 7.8 kPa). LSM was correlated to both fibrosis (Spearman's rho = 0.84, p < .0001) and histological (0.79, p < .0001) stages. These correlations were still found when PBC and PSC patients were analyzed separately. Areas under ROC curves were 0.92 for fibrosis stage (F) > or = 2, 0.95 for F > or = 3 and 0.96 for F = 4. Optimal stiffness cutoff values of 7.3, 9.8, and 17.3 kPa showed F > or = 2, F > or = 3 and F = 4, respectively. LSM and serum hyaluronic acid level were independent parameters associated with extensive fibrosis on LB. The authors concluded that FibroScan is a simple and reliable non-invasive means for assessing biliary fibrosis. They stated that it should be a promising tool to assess anti-fibrotic therapies in PBC or PSC.
The Canadian Agency for Drugs and Technologies in Health (CADTH) performed an evaluation on FibroScan for non-invasive assessment of liver fibrosis (Murtagh and Foster, 2006). It stated that the diagnostic performance of FibroScan is good for identifying severe fibrosis or cirrhosis, but it is less accurate for milder presentations. It concluded that FibroScan is a promising technology, but large multi-center studies comparing a range of emerging non-invasive fibrosis staging technologies are needed. An earlier assessment by the French Committee for Evaluation and Diffusion of Innovative Technologies (CEDIT, 2004) reached similar conclusions, stating that the absence of conclusive evidence concerning the diagnostic value of FibroScan argues against its immediate dissemination. More recently, an assessment by the French National Authority for Health (HAS, 2007) concluded that additional studies are necessary to evaluate the comparative cost-effectiveness of different methods of assessing liver fibrosis (e.g., FibroTest, FibroScan, and biopsy). A technology assessment by the Malasian Ministry of Health (Darus, 2008) reached similar conclusions about the need for additional research for the Fibroscan.
de Franchis et al (2007) stated that transient elastography (Fibroscan) might be of value for the non-invasive diagnosis of cirrhosis; however, its reproducibility needs to be further validated. Furthermore, Berrutti et al (2007) noted that FibroScan is a new, non-invasive method to evaluate liver stiffness and, consequently, the degree of liver fibrosis. Since its use in the clinical setting is of great interest, further studies should define the exact role of this procedure.
de Lédinghen et al (2007) assessed the feasibility of liver stiffness measurement and compared FibroScan, FibroTest, and APRI with liver biopsy for the diagnosis of cirrhosis in children with chronic liver diseases. A total of 116 consecutive children with chronic liver diseases were prospectively included. All except 1 child (58 boys, mean age of 10.7 years) could have non-invasive tests for fibrosis: FibroScan, FibroTest, and APRI, and, when necessary, a liver biopsy (n = 33). FibroScan, FibroTest, and APRI were correlated with clinical or biological parameters of chronic liver diseases, but the FibroScan marker correlated most with all parameters. By histology, the METAVIR fibrosis category score was F1 in 7 cases, F2 in 8 cases, F3 in 6 cases, and F4 in 12 cases. FibroScan, FibroTest, and APRI were significantly correlated with the METAVIR fibrosis score. For the diagnosis of cirrhosis, AUC was 0.88, 0.73, and 0.73 for FibroScan, FibroTest, and APRI, respectively. The authors concluded that these findings indicated that liver stiffness measurement is feasible in children and is related to liver fibrosis. A specific probe dedicated to children and slender patients has thus been developed and is currently under evaluation. The FibroScan equipped with this specific probe could become a useful tool for the management of chronic liver diseases in children.
Shaheen et al (2007) stated that the accurate diagnosis of HCV-related fibrosis is crucial for prognostication and treatment decisions. Due to the limitations of biopsy, non-invasive alternatives including FibroTest and FibroScan have beenn developed. These investigators systematically reviewed studies describing the accuracy of these tests for predicting HCV-related fibrosis. Studies comparing FibroTest or FibroScan versus biopsy in HCV patients were identified via an electronic search. Random effects meta-analyses and AUC were examined to characterize test accuracy for significant fibrosis (F2 to F4) and cirrhosis. Heterogeneity was explored using meta-regression. A total of 12 studies were identified, 9 for FibroTest (n = 1,679) and 4 for FibroScan (n = 546). In heterogeneous analyses for significant fibrosis, the AUCs for FibroTest and FibroScan were 0.81 (95 % confidence interval [CI] 0.78 to 84) and 0.83 (0.03 to 1.00), respectively. At a threshold of approximately 0.60, the sensitivity and specificity of the FibroTest were 47 % (35 % to 59 %) and 90 % (87 % to 92%). For FibroScan (threshold approximately 8 kPa), corresponding values were 64 % (50 % to 76 %) and 87 % (80 % to 91 %), respectively. Methodological quality, the length of liver biopsy specimens, and inclusion of special populations did not explain the observed heterogeneity. However, the diagnostic accuracy of both measures was associated with the prevalence of significant fibrosis and cirrhosis in the study populations. For cirrhosis, the summary AUCs for FibroTest and FibroScan were 0.90 (95 % CI not calculable) and 0.95 (0.87 to 0.99), respectively. The authors concluded that FibroTest and FibroScan have excellent utility for the identification of HCV-related cirrhosis, but lesser accuracy for earlier stages. They noted that refinements are necessary before these tests can replace liver biopsy.
Sagir et al (2008) noted that transient elastography (also known as FibroScan) is a rapid, non-invasive, and reproducible method for measuring liver stiffness, which correlates with the degree of liver fibrosis in patients with chronic hepatitis. However, whether FibroScan is useful in the detection of pre-existing liver fibrosis/cirrhosis in patients presenting with acute liver damage is unclear. In this study, patients with acute liver damage of different etiologies were analyzed. Liver stiffness was measured during the acute phase of the liver damage and followed-up to the end of the acute phase. A total of 20 patients were included in the study. In 15 of the 20 patients, initial liver stiffness values measured by FibroScan during the acute phase of the liver damage were suggestive of liver cirrhosis. However, none of these 15 patients showed any signs of liver cirrhosis in the physical examination, ultrasound examination, or liver histology [performed in 11 of 15 (73 %) patients]. A significant difference was observed in the initial bilirubin levels (5.8 +/- 6.5 mg/dL versus 15.7 +/- 11.8 mg/dL; p = 0.042) and age (32.4 +/- 17.5 years versus 49.7 +/- 15.8 years; p = 0.042) between patients with liver stiffness below or above 12.5 kPa. Six patients with initially high liver stiffness were followed-up to abatement of the acute hepatitic phase; in all of them, liver stiffness values decreased to values below the cut-off value for liver cirrhosis. The authors concluded that transient elastography frequently yields pathologically high values in patients with acute liver damage and is unsuitable for detecting cirrhosis/fibrosis in these patients.
Han and Yoon (2008) stated that although liver biopsy is still the gold standard for assessing hepatic fibrosis, it has some technical limitations and risks. Furthermore, the dynamic process of liver fibrosis resulting from progression and regression can not be quantified by liver biopsy. Thus, alternative, simple, reliable and non-invasive tests are needed to assess the stage of fibrosis. Several non-invasive direct and indirect serum markers able to predict the presence of significant fibrosis or cirrhosis in patients with chronic liver disease with considerable accuracy have been reported. However, since most of these markers require complicated calculations, clinical application is difficult. Transient elastography (FibroScan) is a new method for the evaluation of liver stiffness. It is based on changes in tissue elasticity induced by hepatic fibrosis. The authors noted that based on accumulating clinical data, clinical applications of elastography will increase in the near future.
Sporea and colleagues (2008) stated that evaluation of liver fibrosis can be performed by FibroTest, elastography (FibroScan), and by LB, which is considered to be the "gold standard". At the present, there are 3 techniques for performing LB: percutaneous, transjugular, and laparoscopic. The percutaneous LB can be performed blind, ultrasound (US)-guided or US-assisted. There 2 two main categories of specialists who perform LB: gastroenterologists (hepatologists) and radiologists, and the specialty of the individual who performs the LB determines if the LB is performed under ultrasound guidance or not. There are 2 types of biopsy needles used for LB: cutting needles (Tru-Cut, Vim-Silverman) and suction needles (Menghini, Klatzkin, Jamshidi). The rate of major complications after percutaneous LB ranges from 0.09 % to 2.3 %, but the echo-guided percutaneous liver biopsy is a safe method for the diagnosis of chronic diffuse hepatitis (cost-effective as compared to blind biopsy) and the rate of complications seems to be related to the experience of the physician and the type of the needle used (Menghini type needle seems to be safer). The authors stated that maybe in a few years non-invasive markers of fibrosis will be used, but at this time, most authorities in the field consider LB to be useful and necessary for the evaluation of chronic hepatopathies, despite the fact that it is not a perfect test.
Castera and associates (2008) stated that transient elastography (TE, FibroScan) is a novel non-invasive method that has been proposed for the assessment of hepatic fibrosis in patients with chronic liver diseases, by measuring liver stiffness. It is a rapid and user-friendly technique that can be easily performed at the bedside or in the outpatient clinic with immediate results and good reproducibility. Limitations include failure in approximately 5 % of cases, mainly in obese patients. So far, TE has been mostly validated in chronic hepatitis C, with diagnostic performance equivalent to that of serum markers for the diagnosis of significant fibrosis. Combining TE with serum markers increases diagnostic accuracy and as a result, LB could be avoided for initial assessment in most patients with chronic hepatitis C. These investigators stated that this strategy warrants further evaluation in other etiological types of chronic liver diseases. Transient elastography appears to be an excellent tool for early detection of cirrhosis and may have prognostic value in this setting. As TE has excellent patient acceptance it could be useful for monitoring fibrosis progression and regression in the individual case, but more data are awaited for this application. Guidelines are needed for the use of TE in clinical practice.
In a meta-analysis, Friedrich-Rust et al (2008) examined the performance of TE for the staging of liver fibrosis. Literature data bases and international conference abstracts were searched. Inclusion criteria were as follows: evaluation of TE, LB as reference, and assessment of the area under the receiver operating characteristic curve (AUROC). The meta-analysis was performed using the random-effects model for the AUROC, summary receiver operating curve techniques, as well as meta-regression approaches. A total of 50 studies were included in the analysis. The mean AUROC for the diagnosis of significant fibrosis, severe fibrosis, and cirrhosis were 0.84 (95 % CI: 0.82 to 0.86), 0.89 (95 % CI: 0.88 to 0.91), and 0.94 (95 % CI: 0.93 to 0.95), respectively. For the diagnosis of significant fibrosis a significant reduction of heterogeneity of the AUROC was found when differentiating between the underlying liver diseases (p < 0.001). Other factors influencing the AUROC were the scoring system used and the country in which the study was performed. Age, body mass index, and biopsy quality did not have a significant effect on the AUROC. The authors concluded that TE can be performed with excellent diagnostic accuracy and independent of the underlying liver disease for the diagnosis of cirrhosis. However, for the diagnosis of significant fibrosis, a high variation of the AUROC was found that is dependent on the underlying liver disease. A critique of this meta-analysis by the Centre for Reviews and Dissemination (CRD, 2010) stated that, although sensitivity and specificity data appeared to have been available for many of the studies included in this meta-analysis, the meta-analysis focused on pooled estimates of AUROC. The CRD noted that use of this measure of overall accuracy results in a loss of clinically important information about test performance; it was unclear how many inaccurate test results were due to false positive and how many to false negatives. The CRD critique stated that generation of summary receiver operating characteristic (SROC) curves using a bivariate of hierarchical model may have been more appropriate to this data set; the CRD noted that such models allow generation of summary estimates of sensitivity and specificity as well as potential to assess the significance of sources of heterogeneity. The CRD concluded that these limitations in the analysis mean that the conclusions of this meta-analysis should be interpreted with caution.
Abenavoli et al (2008) noted that in clinical practice there are currently 3 methods for the evaluation of liver fibrosis. First, LB is still considered as the "gold standard" method. Second, serological markers and their mathematical combination were suggested in the last years as an alternative to LB. Third, TE was proposed recently. This technique (TE) is based on the progression speed of an elastic shear wave within the liver. The authors concluded that currently, there are just a few studies capable of evaluating the effectiveness of TE in evaluating chronic liver diseases, mainly in patients infected with HCV. Its application must also be studied in the monitoring of patients suffering from chronic HCV infection and subjected to treatments that can modify their degree of liver fibrosis.
Muñoz et al (2009) evaluated the correlation between values of Fibroscan, liver biopsy, and clinical data among HCV-positive renal transplant patients. A total of 24 HCV/RNA-positive patients with a previous liver biopsy were selected to undergo Fibroscan (transient elastography) and a clinical evaluation of liver function. Fibroscan values were expressed in kilopascals (kPa). As 2 patients were eliminated due to obesity or ascites, these investigators analyzed 22 patients. Thirteen patients (59 %) with fibrosis F0-F1 (METAVIR score) by biopsy and normal liver function showed a mean Fibroscan score of 5.2 kPa (range of 2.3 to 6.8 kPa). Three patients (13.6 %) exhibited F2 by biopsy and normal liver function with a mean Fibroscan score of 8.2 kPa (range of 7.3 to 8.9 kPa). Three patients (13.6 %) with F3 by biopsy and abnormal liver function showed a high mean Fibroscan score of 10.9 kPa (range of 10.5 to 11.6 kPa). The last 3 patients (13.6 %) with F4 (cirrhosis) by biopsy and abnormal clinical data showed the highest mean Fibroscan value of 14.2 kPa (range of 8.9 to 18 kPa). The authors concluded that among renal transplant patients with HCV, the values of Fibroscan seem to correlate with the degree of fibrosis by biopsy and with clinical liver function. Thus, Fibroscan may be useful to follow patients with LD. However, these results should be analyzed with caution due to the small number of cases and retrospective nature of the study.
Andersen and colleagues (2009) stated that liver biopsy is considered the "golden standard" for assessment of hepatic fibrosis. However, the procedure has limitations because of inconvenience and rare but serious complications as bleeding. Furthermore, sampling errors are frequent, and inter-observer variability often poses problems. Recently, transient elastography has been developed to assess fibrosis. The device measures liver elasticity, which correlates well with the degree of fibrosis. Studies have shown that transient elastography is more accurate in diagnosing cirrhosis than minor-to-moderate fibrosis. Most of the studies have been conducted on patients with chronic hepatitis but a few studies have also covered fibrosis and cirrhosis due to other etiologies, and they also demonstrated the high sensitivity and specificity. The authors concluded that transient elastography for assessment of fibrosis may turn out to be a valuable diagnostic procedure and follow-up of patients with chronic liver diseases.
Breton et al (2009) examined the feasibility and reliability of liver stiffness measurement in children with liver diseases. Liver stiffness measurements were performed on 72 children, from 4 to 18 years of age, with potential hepatic fibrosis disease. The clinical, biological, ultrasonographic, and endoscopic parameters were noted to identify children with portal hypertension syndrome. The APRI (ASAT-to-platelet ratio index) test was calculated according to the standard formula. An APRI test score higher than 1.5 indicates significant hepatic fibrosis. METAVIR scoring from 14 liver biopsies was compared to the liver stiffness using the Kappa statistic. A total of 28 patients had viral hepatitis, 20 cystic fibrosis, 16 chronic liver cholestasis, 5 autoimmune hepatitis, and 3 patients had liver fibrosis with uncertain etiology. FibroScan measurements were available in all children. There was good agreement between FibroScan and pathological studies (weighted kappa = 0.814). Only 9 children had portal hypertension syndrome with an average measurement of liver stiffness significantly higher than children without portal hypertension (26.5kPa versus 6.4kPa; p < 0.01). The APRI test for 6 out of 9 patients scored higher than 1.5. The authors concluded that these findings indicate that liver stiffness measurement is feasible in children and seems to be related to liver fibrosis. They stated that larger prospective studies are needed to validate this FibroScan method.
In a meta-analysis of transient elastography for the detection of hepatic fibrosis, Stebbing et al (2010) evaluated its use in comparison with liver biopsy. Studies from the literature were analyzed with a median liver stiffness value in kilopascal given for fibrosis stages according to histopathologic findings on biopsy and best discriminant cut-off levels in kilopascals for significant fibrosis (greater than or equal to F2) and cirrhosis (F4). A total of 22 studies were selected comprising 4,430 patients; chronic hepatitis C infection was the most common etiology of fibrosis. The pooled estimates for significant fibrosis (greater than or equal to F2) measured 7.71 kPa (LSM cut-off value) with a sensitivity of 71.9 % [95 % CI: 71.4 % to 72.4 %] and specificity of 82.4 % (95 % CI: 81.9 % to 82.9 %), whereas for cirrhosis (F4) the results showed a cut-off of 15.08 kPa with a sensitivity of 84.45 % (95 % CI: 84.2 % to 84.7 %) and specificity of 94.69 % (95 % CI: 94.3% to 95 %). The authors concluded that further evaluation of transient elastography to assess LSM is needed in prospective studies to potentially increase the sensitivity and establish its clinical utility.
Myers (2009) noted that non-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease, affecting about 30 % of Western populations and a frequent indication for liver transplantation. The histological spectrum of NAFLD includes simple steatosis, which has a benign prognosis, and non-alcoholic steatohepatitis, a more aggressive form of liver injury that may progress to cirrhosis and its complications. At present, the only widely accepted means of differentiating these lesions, including the severity of hepatic fibrosis, is liver biopsy. However, due to the invasiveness of this procedure, the rising prevalence of NAFLD, and the expected availability of effective therapies for this condition, the identification of non-invasive tools for the diagnosis and staging of NAFLD has emerged as a major clinical and research priority. The author summarized important advances in this field during the past decade, including the development of biomarkers of hepatic fibrosis, apoptosis, and inflammation; novel imaging techniques such as transient elastography; and high-throughput technologies including proteomics and genomics. Future studies must focus on the development of accurate, inexpensive, and reliable tools that can differentiate the major histologic determinants of NAFLD; are responsive to changes in NAFLD severity due to therapeutic intervention and time; and have prognostic significance. Until such tools are developed, liver biopsy remains an important tool in the assessment of patients with NAFLD.
Myers and co-workers (2010) determined the feasibility and performance of TE in a North American cohort of patients with chronic liver disease. Liver stiffness measurements were obtained using TE in 260 patients with chronic hepatitis B or C, or NAFLD from 4 Canadian hepatology centers. The accuracy of TE compared with liver biopsy for the prediction of significant fibrosis (Metavir fibrosis score of F2 or greater), bridging fibrosis (Metavir fibrosis score of F3 or greater) and cirrhosis (Metavir fibrosis score of F4 ) was assessed using area under ROC curves (AUROCs), and compared with the aspartate aminotransferase-to-platelet ratio index. The influence of ALT levels and other factors on liver stiffness was determined using linear regression analyses. Failure of TE occurred in 2.7 % of patients, while liver biopsies were inadequate for staging in 0.8 %. Among the remaining 251 patients, the AUROCs of TE for Metavir fibrosis scores of F2 and F3 or greater, and F4 were 0.74 (95 % CI: 0.68 to 0.80), 0.89 (95 % CI: 0.84 to 0.94), and 0.94 (95 % CI: 0.90 to 0.97), respectively. Liver stiffness measurement was more accurate than the aminotransferase-to-platelet ratio index for bridging fibrosis (AUROC 0.78) and cirrhosis (AUROC 0.88), but not significant fibrosis (AUROC 0.76). At a cut-off of 11.1 kPa, the sensitivity, specificity, and positive and negative predictive values for cirrhosis (prevalence 11 %) were 96 %, 81 %, 39 % and 99 %, respectively. For significant fibrosis (prevalence 53 %), a cut-off of 7.7 kPa was 68 % sensitive and 69 % specific, and had a positive predictive value of 70 % and a negative predictive value of 65 %. Liver stiffness was independently associated with ALT, body mass index and steatosis. The optimal LSM cut-offs for cirrhosis were 11.1 kPa and 11.5 kPa in patients with ALT levels lower than 100 U⁄L and 100 U⁄L or greater, respectively. For fibrosis scores of F2 or greater, these figures were 7.0 kPa and 8.6 kPa, respectively. The authors concluded that the major role of TE is the exclusion of bridging fibrosis and cirrhosis. However, TE can not replace biopsy for the diagnosis of significant fibrosis. Because liver stiffness may be influenced by significant ALT elevation, body mass index and⁄or steatosis, tailored liver stiffness cut-offs may be necessary to account for these factors.
Cholongitas et al (2010) systematically reviewed the literature regarding non-invasive tests (NIT) following liver transplantation. These investigators identified 14 studies evaluating NIT based on serum markers and/or liver imaging techniques: 10 studies assessed NIT in recipients with recurrent HCV infection for fibrosis and 4 studies evaluated predictors of progression of fibrosis in recurrent HCV. Transient Elastography had good discrimination for significant fibrosis (median AUROC: 0.88). Among the serum NIT, APRI had good performance (median AUROC: 0.75). Trnasient elastography performed better than serum (direct and indirect) NIT for significant fibrosis with median AUROC 0.88 (versus 0.66, p < 0.001), median sensitivity 0.86 (versus 0.56, p = 0.002), median NPV 0.90 (versus 0.74, p = 0.05) and median PPV 0.80 (versus 0.63, p = 0.02). Transient elastography compared to indirect serum NIT, had better performance, but was not superior to APRI score. Finally, direct, compared to indirect NIT, were not significantly different except for specificity: median: 0.83 versus 0.69, respectively, p = 0.04. The authors concluded that NIT could become an important tool in clinical management of liver transplant recipients, but whether they can improve clinical practice needs further evidence. Their optimal combination with liver biopsy and assessment of collagen content requires investigation.
Stebing et al (2010) performed a meta-analysis to further assess the use of TE in comparison with liver biopsy. Studies from the literature were analyzed with a median liver stiffness value in kilopascal given for fibrosis stages according to histopathologic findings on biopsy and best discriminant cutoff levels in kilopascals for significant fibrosis (greater than or equal to F2) and cirrhosis (F4). A total of 22 studies were selected comprising 4,430 patients; chronic hepatitis C infection was the most common etiology of fibrosis. The pooled estimates for significant fibrosis greater than or equal to F2) measured 7.71 kPa (LSM cut-off value) with a sensitivity of 71.9 % [95 % CI: 71.4 % to 72.4 %] and specificity of 82.4 % (95 % CI: 81.9 % to 82.9%), whereas for cirrhosis (F4) the results showed a cut-off of 15.08 kPa with a sensitivity of 84.45 % (95 % CI: 84.2 % to 84.7 %) and specificity of 94.69 % (95 % CI: 94.3 % to 95 %). The authors concluded that further evaluation of TE to assess LSM is needed in prospective studies to potentially increase the sensitivity and establish its clinical utility.
Thabut et al (2011) noted that severe portal hypertension is responsible for complications and death. Although measurement of the hepatic venous pressure gradient is the most accurate method for evaluating the presence and severity of portal hypertension, this technique is considered invasive and is not routinely performed in all centers. Several non-invasive techniques have been proposed to measure portal hypertension. Certain methods evaluate elements related to the pathogenesis of portal hypertension through the measurement of hyperkinetic syndrome, or they examine the development of hepatic fibrosis through the measurement of increased intra-hepatic vascular resistance. Other methods assess the clinical consequences of portal hypertension, such as the presence of esophageal varices or the development of porto-systemic shunts. Methods evaluating increased hepatic vascular resistance are fairly accurate and primarily involve the detection of hepatic fibrosis by serum markers and transient elastography. The radiological assessment of hyperkinetic syndrome probably has value but is still under investigation. The assessment of severe portal hypertension by the presence of varices may be performed with simple tools such as biological assays, computed tomography, and esophageal capsules. More sophisticated procedures seem promising but are still under development. Screening tools for large populations must be simple, whereas more complicated procedures could help in the follow-up of already diagnosed patients. Although most of these non-invasive methods effectively identify severe portal hypertension, methods for diagnosing moderate portal hypertension need to be developed; this shows that further investigation is needed in this field.
Tsochatzis et al (2011) studied the performance of elastography for diagnosis of fibrosis using meta-analysis. MEDLINE, EMBASE, SCI, Cochrane Library, conference abstracts books, and article references were searched. These investigators included studies using biopsy as a reference standard, with the data necessary to calculate the true- and false-positive, true- and false-negative diagnostic results of elastography for a fibrosis stage, and with a 3-month maximum interval between tests. The quality of the studies was rated with the QUADAS tool. These researchers identified 40 eligible studies. Summary sensitivity and specificity was 0.79 (95 % CI: 0.74 to 0.82) and 0.78 (95 % CI: 0.72 to 0.83) for F2 stage and 0.83 (95 % CI: 0.79 to 0.86) and 0.89 (95 % CI: 0.87 to 0.91) for cirrhosis. After an elastography result at/over the threshold value for F2 or cirrhosis ("positive" result), the corresponding post-test probability for their presence (if pre-test probability was 50 %) was 78 %, and 88 %, respectively, while, if values were below these thresholds ("negative" result), the post-test probability was 21 % and 16 %, respectively. No optimal stiffness cut-offs for individual fibrosis stages were validated in independent cohorts and cut-offs had a wide range and overlap within and between stages. The authors concluded that elastography theoretically has good sensitivity and specificity for cirrhosis (and less for lesser degrees of fibrosis); however, it should be cautiously applied to everyday clinical practice because there is no validation of the stiffness cut-offs for the various stages. They stated that such validation is required before elastography is considered sufficiently accurate for non-invasive staging of fibrosis.
An UpToDate review on "Epidemiology, clinical features, and diagnosis of nonalcoholic steatohepatitis" (Sheth and Chopra, 2012) states that "A potentially useful non-invasive method for excluding advanced fibrosis is measurement of liver stiffness with transient elastography. However, the approach is not widely available and has not been extensively studied in NASH".
Poca et al (2011) stated that prognostic markers of compensated cirrhosis should mainly investigate factors involved with progression to decompensation because death in cirrhosis is related with decompensation. Portal hypertension plays a crucial role in the pathophysiology of most complications of cirrhosis. Accordingly, hepatic venous pressure gradient (HVPG) monitoring has strong prognostic value. An HVPG of greater than or equal to 10 mm Hg determines a significantly higher risk of developing decompensation. Esophageal varices also can develop when the HVPG is greate than or equal to 10 mm Hg, although an HVPG greater than or equal to 12 mm Hg is required for variceal bleeding to occur. Monitoring the changes induced by the treatment of portal hypertension on HVPG, provides strong prognostic information. In compensated cirrhosis hemodynamic response is appropriate when the HVPG decreased to less than 10 mm Hg or by less than 10 % from baseline, because the incidence of complications such as bleeding or ascites significantly decrease when these targets are achieved. Whether serum markers, such as the FibroTest, may be valuable to predict decompensation should be established. Transient elastography is a promising technique that has shown an excellent accuracy to detect severe portal hypertension. However, whether it can adequately determine clinically significant portal hypertension, and risk of developing varices and decompensation, should be established. Magnetic resonance elastography is also promising.
Pesce and co-workers (2012) noted that portal hypertension has been reported as a negative prognostic factor and a relative contraindication for liver resection. These researchers considered a possible role of fibrosis evaluation by transient elastography (FibroScan) and its correlation with portal hypertension in patients with cirrhosis, and discussed the use of this technique in planning therapeutic options in patients with hepato-cellular carcinoma (HCC). A total of 77 patients with cirrhosis, 42 (54.5 %) of whom had HCC, were enrolled in this study during 2009 to 2011. The group included 46 (59.7 %) men. The mean age of the sample was 65.2 years. The principle etiology of disease was HCV-related cirrhosis (66.2 %). Liver function was assessed according to Child-Pugh classification. In all patients liver stiffness (LS) was measured using FibroScan. The presence of portal hypertension was indirectly defined as: (i) esophageal varices detectable on endoscopy; (ii) splenomegaly (increased diameter of the spleen to greater than or equal to 12 cm), or (iii) a platelet count of less than 100,000 platelets/mm(3). Median LS in all patients was 27.9 kPa. Portal hypertension was recorded as present in 37 patients (48.1 %) and absent in 40 patients (51.9 %). Median LS values in HCC patients with and without portal hypertension were 29.1 kPa and 19.6 kPa, respectively (r = 0.26, p < 0.04). Liver stiffness was used to implement the Barcelona Clinic Liver Cancer algorithm in decisions about treatment. The authors concluded that the evaluation of liver fibrosis by transient elastography may be useful in the follow-up of patients with cirrhosis and a direct correlation with portal hypertension may aid in the evaluation of surgical risk in patients with HCC and in the choice of alternative therapies.
In a multi-center study, Barbero-Villares et al (2012) evaluated the presence of significant liver fibrosis by transient elastography (FibroScan) in inflammatory bowel disease (IBD) patients treated with methotrexate. Cross-sectional study including IBD patients treated with methotrexate from different hospitals. Clinical and analytical data, duration of treatment, and cumulative dose of methotrexate were obtained. Liver stiffness was assessed by FibroScan. The cut-off value for significant liver fibrosis (according to METAVIR) was F greater than or equal to 2: 7.1 kPa. In the study, 46 patients were included, 30 women (65 %), with a mean age of 43 +/- 10 years; 31 patients had Crohn's disease (67.4 %), 13 ulcerative colitis (28.3 %), and 2 indeterminate colitis (4.3 %). The mean cumulative dose of methotrexate was 1,242 +/- 1,349 mg, with a mean treatment duration of 21 +/- 24 months. The mean value of liver stiffness was 4.7 +/- 6.9 kPa. There were 35 patients (76.1 %) with F01, 8 patients (17.4 %) with F = 2, and 3 patients with F greater than or equal to 3 (6.5 %). There were no differences in liver stiffness depending on sex, age, type of IBD, or cumulative dose of methotrexate. The authors concluded that (i) development of advanced liver fibrosis in IBD patients treated with methotrexate is exceptional, (ii) there were no differences in liver stiffness depending on the type of IBD or the cumulative dose of methotrexate, and (iii) FibroScan may be potentially useful for evaluation and follow-up of liver fibrosis in methotrexate-treated patients.
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