FibroScan as a Simple Non-Invasive Screening Tool in Predicting Fibrosis in Non-Alcoholic Fatty Liver Disease Patients

Abstract

The use of FibroScan in a clinical setting has been well established. Numerous studies demonstrate the efficacy of FibroScan as a screening tool in non-alcoholic fatty liver disease (NAFLD) patients. This non-invasive device is a valuable tool in a naturopathic practice to help identify NAFLD patients and those with suspected liver disease. The article will showcase human evidence assessing sensitivity and specificity of this important clinical tool. It is hoped the paper encourages more naturopathic doctors to make this simple, safe, and cost-effective tool available to their patients.

Introduction

Non-alcoholic fatty liver disease (NAFLD) is a condition in which there is an accumulation of excess fat in hepatocytes in people who consume little or no alcohol. The prevalence of NAFLD is estimated to be 20 to 40% of the population (Eddowes et al 2019). Many people with NAFLD are asymptomatic and physical examination is unremarkable. Therefore, early detection and treatment can lead to the prevention of more progressive forms of liver disease.

Using non-invasive testing to detect fatty infiltration and identify the stage of liver disease is imperative in a clinical setting as liver-related health concerns are on the rise. Transient elastography (TE) is a simple and safe ultrasound-based technique to measure liver scarring. FibroScan is a device that utilizes this technique to assess liver ‘hardness’ or ‘stiffness’. This translates to the degree of fibrosis. Assessment of fibrosis provides information about prognosis and allows practitioners to determine treatment. The FibroScan is a powerful tool in naturopathic practice as it provides practitioners with an easy method to evaluate liver health. With chronic liver disease increasing, the FibroScan device can be used as a tool in the management of patients with chronic liver disease and in investigating suspected liver disease. Test results can estimate the degree of liver illness and guide future management and collaboration with other health care professionals.

What is a FibroScan?

FibroScan is a non-invasive device that assesses for stiffness of the liver using TE. Fibrous tissue is harder than normal liver tissue, therefore the degree of fibrosis can be inferred from the liver hardness. This stiffness is evaluated by measuring the velocity of a vibration wave that is generated on the skin (Castera et al 2008). The measurement happens on the surface of the abdomen over the liver. This vibration wave is also referred to as a shear wave. The shear wave velocity measures the time the vibration wave takes to travel to a particular depth in the liver (Castera et al 2008). The result is a measurement of liver stiffness, hence liver stiffness measurement (LSM). In addition, by measuring the ultrasonic attenuation of the echo wave, hepatic steatosis can be quantified. This is termed the controlled attenuation parameter (CAP). A minimum of 10 valid readings are performed to improve test reliability (Castera et al 2008). The LSM varies between 2.5 and 75 kPa (Castera et al 2008). Healthy patients will have a LSM less than 7.0 kPa (median reading 5.3 kPa) (Castera et al 2008). The CAP score ranges from 100 to 400 dB/m and different ranges result in different stages of steatosis. The FibroScan result is then used to determine the fibrosis score. This score ranges from F0 to F4 (see Table 1). The interpretation of the fibrosis stage should be completed in addition to other clinical tools such as ultrasound and serum liver function tests.

Table 1: Scoring System for Fibrosis Stage

F0	No scarring
F1	Mild fibrosis
F2	Moderate fibrosis
F3	Severe fibrosis
F4	Cirrhosis or advanced fibrosis

The FibroScan is an easy method to evaluate liver fibrosis when compared to alternative diagnostic methods available. It is non-invasive and the rapid turnaround time to obtain results is largely appreciated by patients. The wide availability of FibroScan devices based on Vibration-Controlled Transient Elastography (VCTE) technology, affordability, and its modest requirement to attain technical proficiency required to do the scans mean the method can be rolled out easily across most clinical practices.

FibroScan Versus Liver Biopsy

Currently the gold standard tool to diagnose NAFLD is liver biopsy. However, there are some limitations to this such as invasiveness, complications, the potential for subsequent adverse reactions and relatively high price (Cai et al 2021). Complications of liver biopsy include pain and hypotension which can lead to increased length of hospital stay and cost (Hashemi et al 2016). The mortality rate after percutaneous liver biopsy is one in 10000 to one in 12000 and therefore continuous liver biopsy for follow-up is nearly impossible (Hashemi et al 2016). Hence the application of FibroScan as a non-invasive tool to provide evidence about the progression of NAFLD and can be considered as an alternative diagnostic method to liver biopsy in NAFLD patients.

Literature Review

The role of TE in detecting fibrosis is quite valuable, however it comes with some limitations in overweight patients. As obesity and being overweight are prevalent in people with NAFLD, there is hesitancy on the accuracy of TE in detecting various stages of fibrosis in NAFLD patients. Successful measurement decreases remarkably when it is performed on patients with a body mass index >25kg/m2 (Jiang et al 2018). Therefore, an XL probe was developed to account for this challenge and reduce the failure ratio when using TE technology on obese patients (Jiang et al 2018).

In one study, it was reported that for patients with fibrosis stage of >1, sensitivity was 83.7%, specificity was 78.2%, positive predictive value (PPV) was 92.2%, and negative predictive value (NPV) was 65.6%. In cases with fibrosis stage of ≥2, sensitivity was 87.5%, specificity was 78.4%, PPV was 69.9%, and NPV was 89.5%. When liver fibrosis stage was ≥3, the calculated amounts were 93.7%, 91.1%, 82.4%, and 95.9% for sensitivity, specificity, PPV and NPV, respectively. When fibrosis stage was ≥4 sensitivity reached 96.2%, specificity was 92.2%, PPV 55.5%, and NPV 98.5% (Hashemi et al 2016).It is noteworthy that using TE to diagnose fibrosis has a greater sensitivity and specificity when the pathological fibrosis increases. Study authors concluded that using TE in detecting the level of fibrosis in NAFLD cases has high accuracy and can be a good alternative for liver biopsy for patients who cannot or chose not to undergo invasive procedures.

Although most people with NAFLD do not progress to advanced fibrosis, due to the high prevalence of NAFLD, it is one of the main indications for liver transplantation in Europe and the USA. In fact, it has been reported that 30% of patients with NAFLD may develop non-alcoholic steatohepatitis (NASH), 25% may develop fibrosis, 10-20% may develop cirrhosis, and 4% may develop hepatocellular carcinoma (Jiang et al 2018). Therefore, we can see the benefit in identifying those who are at greatest risk of disease progression and who would benefit from treatment.

Another study combined the FibroScan and aspartate aminotransferase (AST) values (called FAST; FibroScan-AST) to identify patients with varying levels of NAFLD (Newsome et al 2020). They noted that the FAST score provides an efficient way to non-invasively identify patients at risk of progressive NASH and thereby reduce unnecessary liver biopsy in patients unlikely to have significant disease. CAP and LSM by VCTE measurements are widely applicable in patients with NASH, with a low failure rate (3%) and good performance in determining the degree of liver steatosis and fibrosis (Newsome et al 2020).

A meta-analysis was performed on the diagnostic accuracy of TE for staging hepatic fibrosis in patients with NAFLD, and the results were positive. They concluded that TE provides an accurate and feasible imaging technique that enables the staging of hepatic fibrosis in NAFLD (Jiang et al 2018). The authors also went on to note that diagnostic accuracies when using TE are higher in those with advanced liver fibrosis (F3) and cirrhosis (F4), than those with less liver damage (Jiang et al 2018).

An additional study was done to analyze the application of TE for diagnosing steatosis and fibrosis in NAFLD patients. The authors concluded that using CAP and LSM for diagnosing fibrosis was a feasible and accurate method, particularly in those with severe fibrosis and cirrhosis (Cai et al 2021).

Conclusion

The benefits of using TE in a clinical setting cannot be overstated. With liver disease on the rise, non-invasive tools to identify and stage the health of the liver are essential. Routine evaluation of patients with suspected liver disease can assist with proper monitoring and treatment. FibroScan offers clinicians and patients a safe, quick turnaround assessment of liver health.

References

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Castera L, Forns X, Alberti A. Non-invasive evaluation of liver fibrosis using transient elastography. J Hepatol. 2008 May;48(5):835-847.

Eddowes PJ, Sasso M, Allison M, Tsochatzis E, Anstee QM, Sheridan D, Guha IN, Cobbold JF, Deeks JJ, Paradis V, Bedossa P, Newsome PN. Accuracy of FibroScan Controlled Attenuation Parameter and Liver Stiffness Measurement in Assessing Steatosis and Fibrosis in Patients With Nonalcoholic Fatty Liver Disease. Gastroenterology. 2019 May;156(6):1717-1730.

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