FibroScan and non-invasive indices for the diagnosis of non-alcoholic fatty liver disease

Background. Non-alcoholic fatty liver disease (NAFLD), an independent nosological entity, is characterized by fat accumulation in hepatocytes not associated with alcohol abuse, and includes a wide spectrum of disorders: from fatty liver, non-alcoholic steatohepatitis to fibrosis with possible outcome in liver cirrhosis. Given the prevalence of this disease, the deterioration of the quality of life of patients, increased mortality from complications, there is a growing interest in developing techniques for accurate and timely assessment of fibrosis. Objective: comparative characteristics of the results of transient elastometry (FibroScan) and non-invasive laboratory indices in the determination of fibrotic transformation of the liver in patients with non-alcoholic fatty liver disease. Materials and methods. The study included patients with NAFLD, who underwent diagnostics and treatment in the department of liver and pancreas of the SI “Institute of Gastroenterology of the NAMS of Ukraine”. Results. We have examined 42 patients with NAFLD, among which 18 (45 %) men and 24 (55 %) women. All patients underwent calculation of non-invasive markers of liver fibrosis: aspartate aminotransferase to platelet ratio index (APRI), fibrosis-4 index, aspartate aminotransferase/alanine aminotransferase ratio, the measurement of liver stiffness using the FibroScan apparatus. Conclusions. Our results are consistent with most studies indicating that the most effective non-invasive index is APRI. The combination of transient elastography (FibroScan) and the APRI may provide a more effective approach to the diagnosis of liver fibrosis in patients with NAFLD.


Introduction
Non-alcoholic fatty liver disease is a condition of excess fat in the hepatic parenchyma in the absence of significant alcohol consumption.The boundary value is 5 % fatty inclusions according to the morphological study, or 5.6 % according to the results of magnetic resonance spectroscopy [1].NAFLD is a worldwide problem with prevalence according to various studies from 12.5 to 51 %.The scope of these indicators is due to the presence of various risk factors and depends on the methods of diagnosis [1][2][3][4].The spectrum of pathology included in the concept of NAFLD consists of simple steatosis, steatohepatitis with the possibility of progression to cirrhosis of the liver and even hepatocellular carcinoma.Recently, there is an understanding that NAFLD is a hepatic embodiment of the metabolic syndrome and is closely related to insulin resistance, the risk of cardiovascular pathology and the development of diabetes mellitus.Rapid progression of fibrosis is a significant problem, although it occurs in a small number of patients with fatty disease.A gold standard for isolating a group of patients at risk of disease progression and to determine the degree of fibrosis is still considered a morphological study, although liver biopsy is associated with certain inconveniences and life-threatening complications [5].
In the last decade, alternative methods of non-invasive or minimally invasive determination of the degree of fibrosis with various liver pathologies, including NAFLD, are actively developing.Among them, the evaluation of various indices calculated on the basis of blood values -the ratio of activity of aspartate aminotransferase (AST) to the number of platelets (APRI), the ratio of aspartate aminotransferase to alanine aminotransferase (AST/ALT), commercial  Transient elastography (TE) measures the propagation velocity of transverse waves at a depth of 25-65 mm and is converted to a liver stiffness measurement (LSM).The resistance of deformation, which depends on the rigidity of the liver, is expressed by the Young's modulus in kilopascals (kPa).The TE uses the formula E = 3pV 2 , which is based on Hooke's law, where E is Young's modulus, p is the density (presu mably 1000 kg/m 3 ) and V is the velocity of propagation of transverse waves [6].

Оригінальні дослідження
The advantages of TE are simplicity, non-invasiveness, as well as high clinical significance.Restrictions on the use of the method are the presence of ascites in the patient, excessively developed fatty tissue, narrow intercostal spaces.The effectiveness of TE in patients with viral hepatitis has already been confirmed by a large number of studies [7,8].At the same time, the diagnostic capabilities of the method in patients with NAFLD have not been adequately described.
The purpose.Comparative characteristics of the results of transient elastometry (FibroScan) and non-invasive laboratory indices in the determination of fibrous liver transformation in patients with NAFLD.

Materials and methods
The study included patients with NAFLD who underwent examination and treatment in the Department of Liver and Pancreatic Diseases at the Institute of Gastroenterology of the National Academy of Medical Sciences of Ukraine.The diagnosis was based on ultrasound examination of the abdominal organs and evaluation of the activity of liver enzymes.Patients with different liver diseases, including viral, drug, autoimmune and alcoholic hepatitis, were excluded from the study.
The activity of ALT and AST in blood serum was determined by the colorimetric dinitrophenylhydrazine Reitman-Frankel method.The laboratory reference range of ALT and AST was up to 40 U/l, and the normal platelet count was 150-450 g/l.
The LSM was performed on a FibroScan 502 Touch F 60156 machine, by the company Echosens (France).The impact of the sensor pin was applied to the right intercostal space at the level of the anterior or middle axillary line and was directed to the right lobe of the liver.Using ultrasonic M-and A-mode, the shear wave propagation velocity and the controlled ultrasonic attenuation parameter were estimated through a standard 4 cm section.The final result was expressed in kPa and was the median value of 10 individual actual measurements.The studies, which resulted in 10 valid measurements with a valid level of at least 60 % and an interquartile range of no more than 30 % of the median stiffness values, were considered successful.The results were evaluated as follows: F0 -0-5.9 kPa, F1 -6-6.9 kPa, F2 -7-9 kPa, F3 -9.1-10.3kPa, F4 -10.4 kPa and more.
The AST/ALT ratio was calculated for each patient.APRI was calculated by dividing the AST level [U/l], expressed as the number of times above the upper limit of normal [ULN], by platelet count [g/l]: FIB-4 was calculated using the formula: The statistical analysis was carried out with the Statistica for Windows 6.0.Since most of the data had a normal distribution, parametric statistics were used -mean (M) and standard deviation (SD).Correlation analysis was used to reveal the interrelations between different values of the investigated indicators.To determine the significance of the differences between the integral indices of fibrosis (AST/ALT, APRI and FIB-4) in patients with minimal (F0-1), moderate (F2-3) and severe (F4) fibrosis, the Student's t-test was applied.The difference was considered significant when p < 0.05.
There were no significant differences in age, platelet count, ALT and AST activity between men and women.The results of a biochemical blood test and platelet count are shown in Table 1.
Correlation analysis revealed a positive relationship between ALT level and liver stiffness (r = 0.32 and 0.47 for p = 0.003 and 0.002 for Kendall and Spearman correlations, respectively), as well as AST level and liver stiffness (r = 0.39 and 0.55 at p = 0.0002 and 0.0001 for Kendall and Spearman correlations, respectively).There was also a positive correlation between APRI and transient elastometry (r = 0.33 and 0.49 for p = 0.002 and 0.001 for Kendall and Spearman correlations, respectively).There was a significant difference in the APRI score between patients with moderate to www.gastro.org.ua,http://gastro.zaslavsky.com.uasevere (F2-3/F4), and initial and severe (F0-1/F4) fibrosis (Table 3).
A weak correlation between FibroScan, APRI, FIB-4 and AST/ALT ratio (Fig. 1-3) can be explained by the small number of patients examined, which necessitates continuation of this study, as well as further monitoring of patients at the stages of NAFLD development.

Discussion
The pathophysiology of a specific disease lies at the heart of the development of biomarkers, reflecting the different stages of the development of this disease.In the case of NAFLD, there are two potential targets for resear chers.The first is the introduction of markers in practice, by which one could distinguish simple steatosis from steatohepatitis -a state with a more serious prognosis.The second goal is to identify the stage of fibrosis.Most prospective cohort studies of patients with NAFLD showed that the prognosis is determined by the stage and level of progression of fibrosis even more than by the presence of necrotic inflammation.Clinical significance is the possibility of differentiation between absence or minimal fibrosis (F0-1), significant fibrosis (F2), severe fibrosis (F3) and cirrhosis (F4) [9].F.C. Kruger, C.R. Daniels, M. Kidd and colleagues evaluated the results of 111 patients with histologically proven fatty liver disease.Biopsy specimens were described according to the NASH clinical research network criteria.Groups with steatosis, steatohepatitis with absent or moderate fibrosis and with severe fibrosis were identified.The sensitivity and specificity of APRI with NFS and ALT/AST ratio were compared.The APRI value was significantly higher with se- vere fibrosis.So the optimal cut-off point was 0.98 with a sensitivity of 75 % and a specificity of 86 %.The NFS for steatohepatitis was significantly lower in the group with severe fibrosis.Positive predictive value was 54 % for APRI, while for NFS it was 34 %.The negative predictive value was 93 % for APRI and 94 % for NFS.Analysis of the data showed that for the diagnosis of severe fibrosis APRI is more preferable than NFS and ALT/AST [10].
A group of American scientists retrospectively analyzed a database of 514 adult patients with NAFLD, assessing the diagnostic accuracy of FIB-4, comparing it with seven other non-invasive markers.The authors concluded that FIB-4 is superior to other fibrosis indices in patients with NAFLD, but there is still a need to develop more sensitive non-invasive markers [11].

Conclusions
In our study, the standard with which we compared the minimally invasive markers of fibrosis was transient elastometry.According to the results of many years of clinical practice, TE measurement by FibroScan is a safe method allowing to determine the degree of fibrosis with high accuracy.The results of our work are consistent with most studies, according to which the most effective of minimally invasive indices is APRI.With its help, it is possible to differentiate the stage of fibrosis with high accuracy (from moderate -F2-3 to severe F4), but its use is limited in the diagnosis of initial fibrosis (F1).The combination of transient elastometry (FibroScan) and the APRI can provide a more efficient approach in the diagnosis of liver fibrosis in patients with NAFLD.Thus, the use of TE with FibroScan in combination with the APRI allows early diagnosis of fibrosis as an alternative to puncture liver biopsy.www.gastro.org.ua,http://gastro.zaslavsky.com.uaПатологія печінки і жовчовивідної системи / Pathology of Liver and Biliary Excretion System Степанов Ю.М. 1 , Недзвецька Н.В. 1 , Ягмур В.Б. 1 , Попок Д.В. 1 Original Researches Гастроентерологія, p-ISSN 2308-2097, e-ISSN 2518-7880 Патологія печінки і жовчовивідної системи / Pathology of Liver and Biliary Excretion System

Integral indicators of liver fibrosis and the reliability of differences between them in patients, distributed depending on the TE
* -р < 0.001.