Grading of Liver Fibrosis using Shear Wave Elastography and Aminotransferase Platelet Ratio Index in Chronic Viral Hepatitis: A Case-control Study

Abstract

Introduction: Liver fibrosis is a progressive disorder that if diagnosed early and staged precisely, allows early clinical intervention that may hinder or slow down the progression to end stage decompensated cirrhosis. Grading of hepatic fibrosis is important not only for diagnosis but also for prognostic evaluation, planning appropriate therapy, and follow-up of patients with chronic viral hepatitis. Liver biopsy has been considered the reference standard for grading liver fibrosis. As liver biopsy is invasive and associated with complications, non invasive serological and imaging techniques like Shear Wave Elastography (SWE) and Aminotransferase Platelet Ratio Index (APRI) have come to the spotlight. Aim: To evaluate SWE alone and together with APRI as a reliable alternative to liver biopsy for diagnosing and grading hepatic fibrosis in chronic viral hepatitis. Materials and Methods: This case control study was conducted over a period of 18 months from October 2017 to March 2019, at a tertiary care hospital in New Delhi, India. Total 120 subjects (60 cases of chronic viral hepatitis and 60 case matched healthy volunteers as controls) were enrolled in the study. Biopsy could not be performed in 10 cases so these cases and their matched controls were excluded from the statistical analysis. SWE was performed using a 1-5 MHz curvilinear transducer (Philips iU22x MATRIX). The APRI and the mean of six SWE measurements (in kilopascals) were calculated for all subjects. The analysis was done using Statistical Package for Social Sciences (SPSS) version 21.0. Results: Among all 50 cases of chronic hepatitis who have underwent biopsy, the mean SWE values corresponding to the histopathological grade of fibrosis i.e., F0, F1, F2, F3 and F4 was found to be 4.48±1.05 kPa, 7.16±0.75 kPa, 8.08±1.05 kPa, 8.44±0.47 kPa and 16.01±3.78 kPa, respectively. The mean APRI values of the cases in F1, F2 and F3 grades showed significant overlap (cut off value between 0.5-1.5). Also, when APRI was used along with SWE, does not have a statistically significant contribution to improve its diagnostic accuracy in liver fibrosis grading. Conclusion: Shear wave elastography has high accuracy in detecting and grading of fibrosis. APRI does not appear to have a significant role in the grading of liver fibrosis however it can be combined with SWE for post-treatment follow-up of chronic viral hepatitis patients thus avoiding the need for repeated biopsy.